The Aluminum Euro Pugsley

a fatbike for everyday

I wasn't really paying attention when fatbikes first became a thing, but anyway somewhere around the start of it all, there was the Pugsley from Surly.  It could manage 4-inch-wide tires while using mostly standard MTB stuff.  In particular, it used a standard 135mm MTB hub in back.  This may seem kind of unsurprising, the tire of course is only around 100mm wide, so a 135mm hub seems like plenty.  You need to remember though that there needed to be room for a derailleur setup.  And not just a modern 1-by setup, you're looking at maybe 3 chainrings up front with 9 sprockets in back, and the chain needed to clear the tire.  They solved this by building the frame crooked: the hub was shoved towards the drive side so it stuck out sufficiently, and the not-drive-side frame curved inwards to catch that end of the hub.  To absorb some of the offset, the rear rim has the holes drilled off-center.  After a while, special fatbike hubs came along that were 170mm and 190mm wide, making things symmetric again, and stronger, no doubt.  So Pugsley was a curiousity, some bike-geek trivia that we could all tuck away in the back of our minds.  It went out of production in 2021.

Well years later, along came me, myself and I, and "we" got two reasonably-priced modern fatbikes with 190mm hubs.  They're kind of fun, sometimes a lot of fun, and the bikes easily showed their usefulness on snow-ice-pavement.  Then a winter commute situation arose that seemed like it might fit a fatbike.  Being experienced in the ways of gear hubs (and also usually annoyed with derailleurs), it seemed like a gear-hubbed winter commuter fatbike was just the ticket.  Getting a 190mm hub is expensive.  I remembered the Pugsley.  I discovered a couple of used examples online, but the price made me hesitate, and then I discovered something else.  Something cheaper.

My eyes somehow picked out, in a random used fatbike posting, the telltale sign: the rear spokes ending in one line, offset from center of the rim.  Apparently, Surly wasn't the only brand that made these twisted offset frames for fatbikes using 135mm rear hubs.  (Forgive my ignorance.)  A local-ish Norwegian-ish brand Diamant also made them, but in aluminum, and with their less-prestigious brand name stuck all over it.  So, Diamant Mammut, model year ~2014.  (They sold the same thing in a different color as Nakamura BigBob, and apparently in the USA as Motobecane Fantom FB4).  This bike also had the requisite mounts for fenders and racks, very much a drop-in Pugsley replacement if you ask me.  I obtained one, at a good price and not too far away.  (Nice thing about used fatbikes is that there seems to be an over-supply of them, and probably the owner didn't ride them enough to wear much out.)

OK, the next part was a bit tricky: how to prepare it for a life of thankless toil.  What was the frame offset, anyway?  What kind of hub is going to work well, and what length of spokes?  For a Pugsley, this will be possible to look up on the net, no such luck for a Mammut.

one plausible version of the wheel geometry

Well, the rear rim was drilled 10mm to the drive side, all the spoke holes in one line.  Its 80mm wide.  Using a flat stick, it looked like the non-drive-side end of the hub stuck out 3mm or so beyond the rim.  A bit of math and it seems the hub offset should be 24-25mm to the drive side, more than a Pugsley (17.5mm they say).  I also disassembled the old wheel and examined the spokes, did what measurements I could, and used https://www.kstoerz.com/freespoke/ to make some estimates.  A bit of trial-and-error, and I found that 250mm and 252mm spokes were sufficient to build the wheel on an Alfine 8, although the 250mm ones were a touch short.  Putting things back into the spoke calculator suggests that the hub offset was more like 20mm, or even 17.5mm.  The smaller offset appears to be necessary to explain how 250mm non-drive-side was short while 252mm drive-side was OK.  However in that case, the hub end should have stuck out more beyond the rim.  I guess that remains a mystery.

Despite all the unknowns, the new wheel fit fine, the brake disc slotted in perfectly, and the chain tensioner lined up where it needed to.  Spoke tension meets my standards, which aren't professional, but thus far I have never had spoke break on any wheel I've built.  (Has to be said, this was my first non-symmetric wheel build.)

I ordered huge fatbike fenders from https://classic-cycle.com/ and they ended up fitting well, although the top of the front fork was a bit of a pinch.  I had to file, cut, and heat-form the fender to sit well... but after that, it sure did sit well.  Those fenders are huge, and quite stiff.  There was also a little messing around to get the fender stays past obstructions, mostly the disc brakes.

front

back

I had to replace the rear hydraulic brake line (in part because a new handlebar required a longer line) and somehow failed to get it tight enough, which was messy.  The oil is non-toxic I guess.  The rear disc got oil seepage on it, but actually that was OK riding on snow and ice.  I just kept riding it until until the oil film gave up.  Hydraulic discs are OK, but IMO too much work for any commuter bike that can avoid them.  Go with Shimano's roller brakes and/or a foot/back-pedal/coaster brake for minimal maintenance.  I did test-fit a wheel with a roller brake to the Mammut frame, but found the unusual shape of the frame on the non-drive-side put it out of reach of the brake arm.  A roller would have been a nice brake for my purposes, but then I would have missed out on the Alfine 8.  (I really like the Alfine 8 combined with the two chain wheels up front.)

Anyway, I rode around my Mammut all winter with the regular summer fatbike tire in back (optimistically labeled as 26x4.5, more like 26x4.2), and a Dillenger 5 (26x4.6) in front.  I was taking it shopping and riding it into the city for meetings.  This was a huge success, I really liked riding it.  It wasn't super fast, and conditions didn't require such a bike, but I liked it.  Those tires made the randomly-distributed crappiness of winter paths minimally bothersome.  A person might look at the tires and assume they float on snow like a small rabbit, but no, not at all.  In fresh snow, you just end up squishing a path twice as wide as anyone else.  They are merely more stable, able to roll on/over more crap without it bothering the rider.  The tires were wide enough to reliably find gravel laying on ice, and also to give some warning when it was time to slide.  A few times the front tire (studded) even slid on ice (in a friendly way), which I can't recall having done, without falling, with a thinner tire.  When the conditions warmed and I first hopped onto a regular bike, it felt small, bouncy and unsafe.  Clear paths eventually fixed that feeling.  I can't deny its good to zip around on high-pressure tires and smooth clean pavement.

Returning to the winter mindset one moment longer, the Mammut worked out so well that we tried a FitNord Rumble 300 for the lady, and that worked out so well that we decided it would be good to build yet another commuter fatbike for a role that involved sitting overnight at a train station.  Spooky.  I found another Mammut, basically identical to the first one, but even cheaper than before.  The guy selling it was pointing out how it still had 31 not-broken spokes in the back wheel.  Perfect, sold!  I wonder if I can make a chain tensioner work with a 27t sprocket on a Nexus Inter-5E (a SG-C7000-5D).  That'll be a project for after summer.

 

Alfine 8

I'm pretty into gear hubs, and I've ridden a lot of them, summer and winter, flat and hills.  Sometimes the market seems pretty static, and it feels like I know all the products.

Well, I had a bike that needed a hub that worked with a disc brake.  The only reasonably-priced reasonably-speced option is basically a Shimano 8-speed, so I could buy what would then be my 5th example of Nexus 8.  I have one with the more efficient bearings (model SG-C6010-8R) which is pleasant, so I wanted more of that, but of course Shimano is playing a game.  You can get those bearings in a Nexus 8, but only for a roller brake (or rim brake) or with electric shifting.  The disc-compatible cable-shifting version (SG-C6001-8D) has the regular bearings, and thats it.  Then they have another offering, the reason Nexus 8 is missing an efficient disc model: the Alfine 8.  Same ratios, but packaged in a shinier can, and different shifter.  Same guts though, I figured.  Costs a bit extra of course.
 

So after much thinking, I got one of those (SG-S7001-8 hub, SM-S7000-8 parts, SL-S7000-8 shifter, CT-S500 tensioner).  It is not merely a repackaged Nexus 8.

If I didn't know the backstory of the Alfine 8, I would not have thought it was related to a Nexus 8.  Not even the Nexus 8 with good bearings can measure up.  Of course it has the same 8 ratios, and you can still kind of feel an extra mechanical engagement going between 4th and 5th (basically a high-range low-range change).  The trigger shifter changes how one interacts with the hub (vs twist), but shifting in general is just better.  The gears themselves are just better.  It is really hard to tell the difference in efficiency or smoothness between 4th (the worst) and 5th (the best) even though I know perfectly well what is involved in generating those ratios.  (Maybe on a road bike I could feel something, but this build is a fatbike.)  The shift quality is also as good as it gets.  For comparison, consider a derailleur: upshifting to a faster/harder gear means dropping to a smaller cog, an easy lovely snappy operation.  The experience of downshifting on a Alfine 8 is very similar if not superior: a nice crisp clunk exactly when you ask for it.  You could call that a tie, perhaps.  Going the other way: downshifting a derailleur is way worse than upshifting an Afline 8.  While the derailleur is trying to push around the chain, the hub does what you ask, when you ask for it, with no particular noise or feel.

It must be emphasized that you should not shift under power with any of Shimano's hubs, but soft-pedaling is perfect, and I can usually just shift quickly at the moment the crank arms are oriented vertically, essentially without interruption.  The hub acts fast, it seems like a physical impossibility for any derailleur to respond as quickly.  So while you are strongly advised to not shift a hub under significant load, you also don't have much reason to try.

The quality of the Alfine 8 shifting that I have experienced thus far is especially remarkable because Nexus 8 has had, in my 4 examples of it, an uninterrupted history of being touchy.  The newer models have better designs than the old ones, but they all have minor persistent shifting annoyances.  In the older hubs, its mostly problems around the 4th-5th transition.  For the newer hubs, its mostly problems holding 8th gear.

Another bit of shifting-related info is that Alfine 8 is a default-high hub, where as Nexus 8 is default-low.  In other words, Alfline 8 without a shift cable installed goes to 8th gear, while Nexus 8 goes to 1st gear.  This also means that shifting to a lower gear on Alfine 8 involves the shifter pulling cable, while the hub spring pulls it the other way when shifting to higher gears.  Likely this cable pulling is a big part of the excellent direct feel when downshifting.  I think its a good choice, because when a person starts downshifting on a hill, they want it to happen immediately.  The cable also passes above the hub, enabling some interesting cable routing, as shown in the picture at the top.  A cable routed as shown, on a MTB frame with sloping top tube, has no low point in which water might accumulate and freeze.

The Alfine 8 follows Nexus 8 by offering a 307% gearing range.  Meaning the highest gear is slightly over 3x as fast as the slowest gear.  This is pretty good for normal people on pavement in my experience, although it can be on the small side when there are big hills.  The bike on which I installed the Alfine 8 came with double chainrings up front.  I kept those double chainrings and the front derailleur unchanged.  By using the Alfine chain tensioner (which looks like a derailleur arm, but is not one) I can switch between the small and large rings just like anyone else (anyone who has such an old-school thing on their bike, anyway).  There is naturally no cross-chaining or similar concerns with the gear hub in the back, just a range of 8 gears and no worries.  This is kind of the cherry on top of the whole setup.  Most of the time I run the big ring, and the small one can be used for major uphills (especially in the winter).  Total range top-to-bottom is now 474%.

A limitation of this setup is that the hub is really not rated to be used at an input ratio approaching 1:1, they recommend about twice that (or half that, depending on your perspective).  So while the big ring is pretty much approved for anyone and anywhere, the small one should be used with a bit of caution.  The way 2nd, 3rd and 4th "gears" are generated is to re-use 6th, 7th and 8th with a reduction gear (which is 1st "gear" when used alone).  That sounds fine, but Shimano seems to place the reduction gear first, so if you run the small ring with 2nd, 3rd or 4th, you're basically running 6th, 7th or 8th with doubled-up small rings.  (If that was possible, or makes any sense.)  Its a lot of torque compared to using 6th/7th/8th natively.  Maybe if you jumped up and down on the pedals you'd replicate it.  Anyway, take care in 2nd/3rd/4th when using the small ring.  I used all the ratios with the small ring at various points during the winter, but also I didn't stand on the pedals.  I have read some say that there is some flex or squish in an Alfine hub, and I sometimes believed I could feel it when using the small ring.  The jury is still out.  I concentrated on smooth application of power and finding zen, and climbed everything that needed climbing.

The main selling point of double chainrings with an Alfine 8 is greater total range, but I also have some moderate uphills where I found the small ring to be worthwhile.  With 22t and 34t chainings, it works out that small-ring-5th is about the same place as big-ring-2nd, but its more efficient.  The 5th ratio is direct drive, whereas 2nd is both 1st and 6th at once (i.e. two gearing stages).  Using 6th and 7th on the small ring is also a bit advantageous, though less so.  It has to be a long hill at the right slope before its worth shuffling around the gears to do it, but I happen to have such a hill.

This being started as a blog on Niholas, I should say that this hub seems like it would be a great cargo bike/trike hub.  Everyone seems to go electric these days, and I don't have anything to say about combining this with a center motor, but those few who want to pedal themselves around should consider Alfine 8.  I would even recommend it over a Nexus 8 with the good bearings (SG-C6011-8R/8V or similar) if you're going with a rim brake.

Summary: Alfine 8 is an attainable masterpiece.

Norway's Auto Union

I randomly happened to see that NAF ("Norway's Auto Union" - Norges Automobil Forbund) reviewed some cargo trikes a couple years back.  (naf.no)  I am apparently a bit slow on these things.  Its written in Norwegian, so maybe not super useful to most of the inhabitants of this fine planet.  I thought however that I could comment.

 (One of those moments where I speak into the vast uncaring void of the internet.)

They rated Nihola as OK.  I note in particular three points: (1) stability wasn't great, (2) the electric motor was a bit eager, and (3) they seemed to want child heads to be entirely enclosed in walls.

1. Stability - I can totally believe it.  A Nihola with an empty box is a bit tippy, especially for a new rider.  Then add a heavy battery directly over the rear wheel, the most tippy place, and its not going to help matters.
   
2. The electric motor - Yeah, you have derailleur gears on your heavy e-trike (or a heavy e-bike) and one way to make it do something when you're stopped in the wrong gear, which seems likely to happen, is to make the motor super excitable.  (Just guessing thats what happened.)
   
3. Kids need walls - My kids got to look around and feel wind in their hair, they did not cycle around in a bunker.  The roof usually stayed at home (or at least under the seat).  In any case, kids sit inside an elbow-high steel cage, that has to be good enough.  Better than any grown cyclist.  (Note also that it gets a lot harder to tip the thing with passengers up front.)
   

On points #1 and #2, what I think is that too many people are choosing e-trikes based on perceived needs, and getting a worse experience for it.  Sure you can zip right along, but these things are best slow anyway.  You get a less stable, more jumpy, more expensive, heavier, more tempting theft target, that is more likely to break.  Just go with a Nexus 8 hub and feel the zen.

 Obviously though, trends, culture, and ideas stampede onwards without much concern for making sense.  I spent many hours in Copenhagen this past summer, saw a bunch of e-trikes with those derailleur gears.  Almost totally flat city, a hive of hub gears, considerable tradition of not-electric bikes/trikes, and boom there are lots of people choosing derailleur-gear e-trikes.  (Screams at the internet.)

Do not submerge your Nexus gear hub

Title says it all.  These things hold up great in rain and snow and filth, but really badly under water.

Funny thing, its rained a lot here recently.  So a family member was on the way home from work, and found that the river was invading the bike path.  We had a talk on the phone, and I failed to think very far ahead, which did generate some extra work and possibly lead to long-term damage to some bike components, but on the other hand, now I have had a new experience.

So the family member found a way through the flooded section that was acceptable for legs, but which saw the bike pushed through water that was way over the wheel centers.  In fact this was an electric bike, and the electrical-connector-end of the battery went in the river, plus the motor, and all the control circuits.  Did you know an E-bike could survive that?  I did not.

Anyway the bike was apparently making some funny noises when it got home, but only while pedaling.  I had also in the back of my mind the old Nexus 7 that a kid had (apparently) submerged in a forest, followed by neglect, events that accelerated the crapification process of that hub remarkably.  So the wheel came off, the hub guts came out, and it was quite wet inside.  I think a small amount drained out as I took it apart.  So it got a long tour at the end of the boot drier before re-greasing and re-assembly.

The hub seemed a bit under-greased, perhaps that made the water ingress worse.  This hub at the time of this writing is their latest Nexus 8 model, a SG-C6001-8C (coaster brake, regular bearings).  So it ought to have the best available seals.

So the next day I went to assist this family member on the way to work, so I could see that the bike was OK.  (It was after all an E-bike that got partially submerged, plus the hub I worked on.)  We came to an uninteresting little underpass that had a puddle in it.  Which was deeper than the wheel centers, this time on two bikes.  (I wonder how many bikes that claimed in the past couple days.)

So when I got back home, I had front and rear hubs to think about.  I wasn't really sure there was enough time under water to make a difference, probably under 10 seconds of submersion.  This was however my favorite Nexus 8, a SG-C6010-8R.  (It has the good bearings on the planet gears.)  So I took it all apart, and sure enough there was some water droplets in there.  Less water than the other hub, but not dry.  It also got a tour with the boot drier.

So anyway, approximately no submersion is acceptable for a Nexus 8, not even the latest models.

I don't actually know what the long-term effects of not taking action would have been.  Some internal rust, certainly on the first hub.  It also seemed low on grease, so it would probably have undergone rapid crapification.  Even with intervention, I can't be certain that these two didn't retain water deep inside where it will rust in the coming weeks and months.  (I have never taken hubs apart beyond exposing the innards as a unit.)  I also do not know what amount of water ingress is tolerable for these hubs.  They are designed to be used in wet conditions, and thats how I always use mine.  I have never had an internal rust issue except for the Nexus 7 that took a bath and subsequently neglected for a year or so.  That hub still lives in a kids bike.

I should also say that the front hub on one bike also needed new grease after all this bathing.  The other hub... is an electric motor that shows no outwards signs of harm.  Not something I am eager to take apart.  Fingers crossed.

Greasing a Nexus

Niholas usually have hub gears, and these days those are usually Shimano Nexus 8 after the unfortunate demise of SRAM's P5 and S7 on the market.  These need grease once in a while.  For me, that means whenever they have a hard time holding one or more gears, or otherwise seem too crappy.  (Fun thought on crappiness: at least in hilly Oslo conditions, switching between Nexus 7 & 8 and SRAM S7 is a process of relief from the irritations of whatever hub you were riding, followed by growing irritation at the issues of the one you are now riding.)

So for a while after moving to Oslo I took my hubs down to Copenhagen for greasing, which came to an abrupt end after one visit to a well-established chain-store shop in Birkerød (north of Copenhagen).  I brought them two wheels without the bikes, one a Nexus 8 and the other a Nexus 7, and got back to two nicely cleaned hubs a couple days later.  All was well until I arrived home in Oslo and put the Nexus 7 to use as winter began.  Soon it was leaking, and smelled fruity.  Actually the smell was exactly like a "Muc Off" chain lubricant which has the distinction of not only smelling fruity, but being somewhat pink in color, achieving who knows what.  (The leakage wasn't pink of course, it was filthy, but I am really suspicious about the origin of the lubricant they used at the shop.)  So it leaked and stank, and eventually seemed rougher, and if I recall correctly was not as secure about holding a gear.  To cut the story short, the Nexus 8 had the same issue.

Screw the so-called professionals, it was time to fix this myself (the internet explains how).  I don't intend to write a hugely detailed rundown of how to take apart a hub, but basically you take the hub apart on the drive side until the sprocket is removed, then flip it over and use two thin wrenches (cone wrenches) to remove two nuts from the axle, then lift off the non-drive-side end of things and drop out the internals via the drive side.  I like to put the axle nut on the non-drive side to make it nicer to hold, and I made a handy hub-holder by drilling a hole in a board.  High tech stuff here.

tools of a nonprofessional hub greaser

10 year old Nexus 7 (SG-7C18)
after a dip

Nexus 8 (SG-8C31) dripping out
some pink stink after two
dip & grease rounds

I clean the hub shell out thoroughly via baby wipe and toilet paper, and also remove some grease-mess from the surface hub internals, but not so much.  I have not thus far attempted any disassembly of the hub internals, although I think the Nexus 8 might benefit from getting grease into gears that are not otherwise exposed (thats on the to-do list).  Hubs with coaster ("foot") brakes (as mine have) can have the brake pads jump off and they need to be set back correctly.  The brake pads on Nexus 7 have a spring which pulls them a little closed, so they need to be pried open a bit to sit on the hub.  You'll figure it out.  Kind of like Legos, with grease.

Shimano recommends a dipping kit, so I found one online, plus their official hub grease.  I dip the hub for "a while" and then remove it so it can drip for "a bit" before I put grease all over interesting places.  One thing I wondered in the years before I attempted this was how to grease the coaster brake components.  My answer: a whole ton of grease, just go nuts at that end of the hub.  Often I have extra grease pressing itself out the non-drive-side the first ride, but I don't much care.  Dry brake pads are lame, and there are hills here in Oslo.  I have read that some people may want different grease for the braking surfaces, so far I have not been sufficiently professional (or wise) to do anything like that.

So I have now done this procedure on a Nexus 3 & 8, plus at least three Nexus 7's, and of these hubs I've opened several more than once.  (Score keeping: I have 5 Nexus 7 hubs, also a rare Nexus 5 SG-5R30.)  But about opening some more than once.  You see, there is a drawback to doing this yourself.  Shimano likes cup & cone bearings, and those need to be tightened correctly, or else.

Nexus 7 (SG-7C30) with sad bearings

Nexus 8 (SG-8C31) with sad bearings

Now, I have read a bit about how to tighten cup & cone bearings and honestly what I read was not super helpful in this context, which is a gear hub with a coaster brake and bolt axles.  My current procedure is to get the wheel set in the frame, pull it back so the chain is sufficiently tight, and then tighten down the drive-side bolt in a serious way.  The frame should either be upside-down or hanging on something; the rear wheel needs to spin freely.  Then I loosely attach the brake arm and non-drive-side axle bolt, but do not tighten it so much that any pressure is applied to the nuts that adjust the bearings.  Then I turn the first (the larger) of the two tightening (cone adjustment) nuts until the wheel shows signs of increasing resistance when spun.  At some point I decide that it seems tight enough, then I tighten the second (smaller) nut good and tight (while holding the larger in place) and properly tighten the axle nut.  Now the wheel is probably tighter than it was before the axle nut was tightened.  If its too tight, rewind a bit, loosen things, tighten things again.  Spin the wheel a lot and go by feel.  If it spins really easily, thats probably bad.  Next time I go by a Danish bike shop, I should remember to spin some back wheels and get a feel for factory-fresh resistance.

My first bearing tightening issue was a bearing retainer failure (non-drive side) during or shortly after a big downhill on a hot-for-Oslo June afternoon, apparently braking was the final stress that tipped things over.  Once I reached the flat at the bottom of the hill, it was a fairly short distance before the wheel started crunching.  The bearings had lasted about 6 weeks after I had greased the hub.  I was surprised by this, because it wasn't the first Nexus 7 that I had greased up (the first one was the hub contaminated in Denmark).  I greased the first hub on the 1st of Feb 2018, and has done fine since.  I concluded that the cone adjustment nuts had probably loosened on this 2nd Nexus 7.  I grabbed the bearings and retainer from a different wheel, put things together again, and its been fine since.

I also greased the Nexus 8 that was Muc Off'ed in Denmark.  I was very pleased how the wheel spun so easily and had no observable looseness (as in, I observed no play).  Seemed good.  I guess I rode a couple hundred km's before I decided to do an uphill stretch standing on the pedals in 5th (direct drive).  As before, the bearing retainer (also non-drive side) broke into bits and this time the wheel was partly jammed, couldn't even roll the bike all the way home.  With this failure, it seemed clear the cone adjustment nuts where not loosened, apparently they were just not set tight enough.  So I fixed that also by replacing the bearings and retainer, but it wasn't so long ago that I can say how it will last.  (Side note: the bearings and retainer for Nexus 7 and 8 are interchangeable, at least for the hubs I have, and spares are possible to order.)  This second failure was the point that I adopted the procedure outlined a couple paragraphs above.

Anyway moving on to farther in the past, in 2017 we had bought a gear-hub bike for our son down in Denmark and almost immediately it went out into the forest and got a bit wet.  Apparently more wet than we realized.  We left it in Denmark until the next summer, and when we returned I noticed some roughness while spinning the rear wheel.  Upon returning to Oslo with the bike, I took the hub apart and was met by rust, as shown.

rust in the drive side bearings
of a Nexus 7 (SG-C3000-7C)

rust on the guts

rust in the shell

In light of the amount of time that bikes with these gear hubs are ridden or parked in the rain, I'm pretty amazed that this hub had sufficient water ingress to rust.  We did get it discounted from a bike shop, maybe it had more of a history than we realized, or perhaps these hubs are particularly vulnerable to water found in forest settings.  Or perhaps my son submerged it.  Anyway it works pretty fine except when coasting, then it rumbles.

A bit of a shame that the newest Nexus 7 in the fleet was damaged so soon after purchase, but I'll see about getting some years out of it anyway.  As much as I love to hate these things, they last forever.

Gear hubs and high torque

So gear hubs are a bit limited compared to derailleur gears when it comes to input torque.  I've been playing with gear hubs and high torque for some years, and two things come to mind:

• torque can plain break the hub (done that)
• torque can loosen the axle nuts (Nihola has front-angled dropouts, so the axle can move if its loose)

I've only broken one hub with torque, a SRAM P5 with 38f and 24r sprockets, where I was standing on the pedals while trying to rock a Nihola over something in the forest.  I've used a similar input ratio on two examples each of Shimano Nexus 7 & 8, one SRAM P5 I didn't break, and now one SRAM S7.  Having been using a ratio like that on various hubs in the hills here, I'm starting to feel like I have information to share.  So lets do that.  On the two Nexus 7's, even with the 38x24 input ratio I need to work fairly hard to climb the steepest hill of my commute, and the gears that give 1st 'gear' and contribute to 3rd 'gear' do get a bit nasty after a while, rough and unpleasant, but still functional. (As always, fresh grease seems to help.)  The SRAM S7 hasn't been through long enough abuse yet (and no winter use), but 1st and 2nd do feel a bit rough when pushed.  Its nice that '1st gear' isn't being reused as part of '3rd gear' on S7, like it is on Nexus 7.  S7 by comparison has a lovely smooth 3rd, not to mention 4th and all the high ratios.  So I can say Nexus 7 is fairly tough, but also it gets nasty, the P5 & S7 siblings are lovely but probably not great with torque, and also out of production.

Nexus 8 seems uneffected by a few seasons of hard climbs, though of course the 3rd & 4th 'gears' are sufficiently unpleasant right from day 0, and the 4th-5th shift is always a bit iffy.  The 1st gear on Nexus 8 is really a great gear for high torque, isn't bothered at all, doesn't get unpleasant when worked.  Nexus/Alfine 8 are often used with crank-mounted electric motors, which is a big vote of confidence.  Still I don't like these hubs on the hills because everything sitting between 1st and 5th seems inefficient, and I need to spend a lot of time there on my commute.

My one line verdict: Rohloff is flawless, or an Alfine if you don't need perfection.

I have a theory about gear hubs and torque.  Of course the input torque goes up as you increase the ratio of the rear sprocket to the front sprocket, and torque breaks hubs at some point.  (Would break anything, at some point.)  But the work being performed is actually determined by the radius of the tire & wheel, and the load which is bring pushed up the hill.  So the problem isn't the input ratio, the problem is the tire, the load, and the hill, and the input ratio simply makes it easier for the rider to apply the needed torque to climb the hill, given the tire, and the load.  So if you're already going to climb hill X (maybe you live on top of it) with a 20-tooth sprocket and thats a lot of work, its not more abusive to your bike to make your life less painful by jumping to 22 or 24 teeth.  (Having said that, I do try to be more careful on hubs with high input ratios.)

Loose axle nuts are the real day-to-day irritation of high input torque on a common gear hub.  In particular, it effects bikes that do the standard Danish thing: using front-facing dropouts and no means to hold the axle in place except the nuts.  This can manifest in various ways.  For example, this spring I have switched to using a freshly-greased S7 to commute the 21kms between home and work.  I have some experience about how to install these things, so I cleaned the axle threads, applied some grease, and torqued the nuts good.  After some time I had noticed that the it seemed an internal component of the hub would rotate some distance when I shifted into 5th & 6th, and again when I shifted into 2nd & 3rd.  It didn't manifest in 4th as far as I could tell.  I could get 'the rotation' in 3rd gear, shift right to 5th, and feel it again.  I had initially checked the axle nuts when this started happening, and found them tight, so I supposed the well-used hub was showing its age.  After some time I started getting a noise while climbing in the low gears.  I stopped many times to look for its cause.  I noticed the kickstand passed pretty close to the spokes, but didn't touch when I tested, and the noise only happened in the low gears.  At the same time, I'd been having some trouble with the chain hopping off the sprockets.  Eventually I took 15 minutes and dug into it, and the nuts were loose, but it took some effort to actually move the wheel by hand.  I needed to use a flat screwdriver to pop the anti-rotation washers free of the frame, needed to loosen the brake torque arm, then worked a bit on getting the wheel pulled back tight and torqued good.  That solved the rotation, the noise, and loosing the chain.  This was an especially tricky case of loose nuts, usually I can see the wheel has gone a bit crooked in the frame, but not on this bike.  This bike apparently allowed/forced the wheel to re-center itself every time I got off to look.

Many times I've dealt with this on Niholas as well.  About the only solution at hand is making sure the axle nuts are applied tight, which presupposes that the threads are clean and lightly greased, so that the nuts don't get bound up on the threads themselves.  The grease of course should not get all over friction surfaces between the anti-rotation washers and the frame.  Been a while since I've had to mess with this on a Nihola actually, but its worth paying a bit of attention each time the rear wheel is installed, so its done right, and the axle stays where you intended.  Also I think its worth carrying a 15mm wrench.

Gear hub madness

Today I came across a good description of how the new SRAM G8 hub works, and I worked through the ratios in a spreadsheet. Its a strange hub and it took me a while to figure out what was going on, even when someone had already attempted to explain it. This got me thinking about another difficult nut to crack, the Alfine 11.

As far as I can determine, no one has done a teardown of an Alfine 11, counted the teeth, or posted any particular information about how its ratios are created.  In the past, I've thought it was quite similar in design to a Nexus 7, but now I've changed my mind.  However before that, lets go on a tour of gear ratios in hubs.

Gear hubs are made up of planetary gear sets: http://en.wikipedia.org/wiki/Epicyclic_gearing

Generic three speed:

The most basic hubs have one gear set, giving three speeds.  In the middle there is direct drive, then one ratio increased and one ratio decreased (the inverse of the increased ratio).

gear	1	2	3
ratio	0,750	1,000	1,333
ratio change		33 %	33 %
name	1/A	-	A
calculated ratio	0,750	1,000	1,333

SRAM P5:

This was extended to make 5 speeds such as the SRAM P5 by placing two gear sets into one module, so that one of two ratios could be used at a time, either up or down.

gear	1	2	3	4	5
ratio	0,633	0,781	1,000	1,281	1,579
ratio change		23 %	28 %	28 %	23 %
name	1/A	1/B	-	B	A
calculated ratio	0,633	0,781	1,000	1,281	1,579

SRAM S7:

This also worked for 7 speeds, such as the SRAM S7.

gear	1	2	3	4	5	6	7
ratio	0,574	0,677	0,809	1,000	1,236	1,476	1,742
ratio change		18 %	19 %	24 %	24 %	19 %	18 %
name	1/A	1/B	1/C	-	C	B	A
calculated ratio	0,574	0,678	0,809	1,000	1,236	1,476	1,742

SRAM i-Motion 9:

It even worked for a 9 speed, the i-Motion 9.  This hub was basically a failure on the market, apparently because it was too heavy, rough running, expensive, and poorly sealed against weather.  However it was apparently well constructed, and it did achieve 9 tight and evenly-spaced ratios while using only one planetary gear at a time, potentially giving high efficiency.  I think its a shame it didn't make it.

gear	1	2	3	4	5	6	7	8	9
ratio	0,542	0,621	0,727	0,853	1,000	1,172	1,375	1,611	1,844
ratio change		15 %	17 %	17 %	17 %	17 %	17 %	17 %	14 %
name	1/A	1/B	1/C	1/D	-	D	C	B	A
calculated ratio	0,542	0,621	0,727	0,853	1,000	1,172	1,375	1,611	1,844

Shimano Nexus 4:

But there are other fun things that might be done.  Consider a Nexus 4, which made four ratios from a set of three planetary gears, by only increasing ratios.  Leaving out the ability to decrease ratios simplified the hub.  This simplification, where each planetary gear is only used to either increase or decrease ratio but not both, is a major theme of all recent hubs.  There i-Motion 9 above might well have needed only 4 planetary gears to get 9 beautiful-looking ratios, but those 4 gears were too complicated.

gear	1	2	3	4
ratio	1,000	1,244	1,500	1,843
ratio change		24 %	21 %	23 %
name	-	A	B	C
calculated ratio	1,000	1,244	1,500	1,843

Shimano Nexus 5:

But all these hubs have fairly large steps between the gears.  Especially the gap between direct drive and the first ratio up or down was problematic.  While i-Motion 9 got this down to 17%, it was apparently unpleasant.  Even the 22% gap on Nexus 8 leads to some gear whine.  So Shimano got busy with dual-stage compounding its planetary gear sets.  Below is the Nexus 5, which used three planetary gears in two sets, and has no direct drive ratio at all, but is very smooth in my experience.

gear	1	2	3	4	5
ratio	0,750	1,001	1,159	1,335	1,545
ratio change		33 %	16 %	15 %	16 %
name	1/A	B/A	C/A	B	C
calculated ratio	0,750	1,001	1,159	1,335	1,545

Shimano Nexus 7:

The Nexus 7 is similar, but with four planetary gears arranged in two sets.  I've used two of these extensively and never been satisfied with either their smoothness or efficiency, but they seem to sell in vast quantities in Denmark.

gear	1	2	3	4	5	6	7
ratio	0,632	0,741	0,843	0,989	1,145	1,335	1,545
ratio change		17 %	14 %	17 %	16 %	17 %	16 %
name	1/A	1/B	C/A	C/B	D/B	C	D
calculated ratio	0,632	0,741	0,844	0,989	1,145	1,335	1,545

Shimano Nexus 8 / Shimano Alfine 8:

But thats not the only way to do multi-stage compounding.  The Nexus/Alfine 8 is a lot like the old Nexus 4 with a new planetary gear enabling the four original ratios to be used twice.  This leaves a direct drive gear in place which is good, but creates an odd situation where the least efficient gear (4) is right next to the most efficient (5), and switching between the "high" and "low" gears can be problematic.  Still, this seems to be a robust design.

gear	1	2	3	4	5	6	7	8
ratio	0,527	0,644	0,748	0,851	1,000	1,223	1,419	1,615
ratio change		22 %	16 %	14 %	18 %	22 %	16 %	14 %
name	1/A	B/A	C/A	D/A	-	B	C	D
calculated ratio	0,527	0,645	0,748	0,851	1,000	1,223	1,419	1,615

Rohloff:

And then there is the monsterous 14 speed Rohloff, that uses 5 planetary gears in three sets.  Gears 3 and 5 actually use triple-stage compounding, which is hard to notice in my experience.  In some ways this combines concepts which are found on both Nexus 7 and Nexus 8, sort of a combination of those designs.

gear	1	2	3	4	5	6	7	8	9	10	11	12	13	14
ratio	0,279	0,316	0,360	0,409	0,464	0,528	0,600	0,682	0,774	0,881	1,000	1,135	1,292	1,467
ratio change		13 %	14 %	14 %	13 %	14 %	14 %	14 %	13 %	14 %	14 %	14 %	14 %	14 %
name	1/B * 1/A	1/C * 1/A	D/B * 1/A	1/A	E/C * 1/A	D/A	E/A	1/B	1/C	D/B	-	E/C	D	E
calculated ratio	0,279	0,317	0,360	0,409	0,464	0,528	0,600	0,682	0,774	0,881	1,000	1,135	1,292	1,467

SRAM G8:

Here is the SRAM G8 in all its confusing glory.  Five planetary gears in two sets, sort of arranged like a backwards Nexus/Alfine 8.  No direct drive, and 6 of the 8 ratios are two-stage compounded.  http://sheldonbrown.com/sram-g8.html

gear	1	2	3	4	5	6	7	8
ratio	0,609	0,710	0,803	0,903	1,054	1,204	1,355	1,581
ratio change		17 %	13 %	12 %	17 %	14 %	13 %	17 %
name	1/B	1/C	E/A	E/B	E/C	D/A	D/B	D/C		1/A	D	E
calculated ratio	0,609	0,710	0,803	0,904	1,054	1,204	1,356	1,580		0,5411	2,2258	1,4839

Shimano Alfine 11:

Then finally we get to the Alfine 11.  I spent some time on this.  There are lots of ways to make a good approximation of the published ratios, but the way I am most satisfied with uses four planetary gears arranged in three sets.  The main difference between this and Nexus/Alfine 8 is that one gear (number 7) is able to combine with gears 8 and 9 to create ratios 10 and 11.  Then all those resulting 5 ratios are re-used in positions 2-6.  This very nicely explains the 29.2% gap between gears 1 and 2... its same ratio as gear 7 has.  This also has no planetary gears which are used to both increase and decrease ratios, which appears to be very much out of style, it explains the alternating 13% and 14% ratio changes, and it explains how the 11 speed is able to match the weight of the 8 speed.  Essentially, the same number and strength of gears needed to be used.

There is no direct drive ratio, which is instead replaced by a triple-compound approximation, I imagine to achieve mechanical simplicity.  The only difference between 2-6 and 7-11 is whether or not the "low range gear" is active.

gear	1	2	3	4	5	6	7	8	9	10	11
ratio	0,527	0,681	0,770	0,878	0,995	1,134	1,292	1,462	1,667	1,888	2,153
ratio change		29,2 %	13,1 %	14,0 %	13,3 %	14,0 %	13,9 %	13,2 %	14,0 %	13,3 %	14,0 %
name	1/A	B/A	C/A	D/A	(B*C)/A	(B*D)/A	B	C	D	B*C	B*D
calculated ratio	0,527	0,681	0,770	0,879	0,995	1,135	1,292	1,462	1,667	1,889	2,154

Further reading, here is the grand daddy of complicated bike gear hubs: http://sheldonbrown.com/elanratios.html

Nexus 8 SG-8C20

When I broke the SRAM P5 that came with our blue Nihola, we spent considerable time trying to find the right replacement.  It would have been a Nuvinci N360 with a roller brake, except the shop in England selling N360's wasn't really interested in ordering one with a roller brake mount, and bike shop employees in Denmark seemed to have little time for "strange" hub gears.  Basically people were not interested in being paid to do anything they didn't normally do; perhaps the margins were too small for them to care.

The Shimano Nexus 8 with foot brake would be another good option, except in Denmark (and some other countries) it was only possible to order the old SG-8C20 version.  It seemed that Shimano refused to sell the SG-8C31 until the old model was sold out (on a per-country basis), and no one could order one for me, nor could I find any for sale online.

I also considered the SG-8R36 with a roller brake, but it was more expensive and we wanted to stick with a coaster brake (foot brake) unless we had a really good reason to change.

So we ordered the old model, the SG-8C20.  It had probably been sitting on a warehouse shelf for years.  I installed it myself.  Right away I had some issues because the "cassette joint" wanted to occupy a bit of space which the chainstay was using.  I installed some extra washers and bent the cassette joint a little to get the shifting in order, but the whole thing was always a pain to fiddle with.

The hub itself was functional, but made me nervous that it was headed for premature death.  From day #1 it made various clicks and had various shifting issues between gears 4 & 5.  Gear 5 (direct drive) seemed like it might slip at any time (but it never actually slipped, except after shifting from 4th).  Adjustment of the shifter could address the various issues but always at a cost somewhere else.  At some point, the clicking and humming alone was enough for me to know what gear my wife was pedaling in, if I rode along behind her.  Still, it was working.

Happily it seems there are ways to address these problems.

The Nihola company had started using Nexus 8 hubs (I presume SG-8R31), so when visiting Copenhagen I checked with them to see how they handled the cassette joint.  Turns out they had some different non-turn washers that I didn't realize existed: 5L and 5R.  They sold me a set of them for a reasonable cost, and one source of irritation dissappeared.

On my next visit to Denmark I took the Nexus 8 into Byman Cykler and had them put some new grease in it.  Now this was the magic the hub needed.  Most of the noises and shift problems vanished and haven't come back (in over 4 months).  So, moral of the story: hubs like fresh grease.

There is one lingering irritation with this hub, however.  It works its axle nuts loose over time, and then pulls itself crooked in the frame.  I guess I'm putting too much torque on it.  Always carry a 15mm wrench!

So now I can make a bit of a verdict on the Nexus 8 with coaster brake as a hub for a Nihola.  Its pretty good.  A bit rough in 3rd and especially 4th gear, in fact its generally a rough hub.  Buts its strong: ours is set up with a 24t sprocket on the hub and 38t on the crank, well beyond any ratio any hub company endorses, and I've put my entire weight on it countless times, plus added arm strength.  I've gotten small blisters from pulling on the handles to force the pedals around.  (I do these terrible things in 1st gear exclusively, which is probably the strongest gear available.)

The Nexus 8 is a strange hub.  Its not symmetric (i.e. the top ratios are not mirror images of the bottom ratios) and the least efficient gears are in the middle of the range (3 & 4) rather than the ends.  However this works out well enough on a Nihola.  For any real hill, I just drop to 1st gear and pedal.  On any reasonably flat ground, I can stick to gears 5-8, which are mostly pleasant.  I never make any strenuous effort in 3rd or 4th gears.

The foot brake is strong enough to slide the rear tire at will, though Oslo hills might cook the hub.  More than once I have been unable to touch the hub's shell after a good downhill.  After that happened a few times, I decided to have a V-brake installed in addition to the foot brake, so now that Nihola has two rear brakes.  Overall I am very pleased with the foot brake.  I'm convinced foot brakes are the best rear brakes for Niholas, except possibly in deep snow, ice, or mud.

But is the Nexus 8 a worthy upgrade over a SRAM P5?  For any moderately serious cyclist, I would say yes.  The ratios are closer, which makes it easier to go fast without knee injuries.  The lowest ratio is good and low.  The hub itself is stronger.  It shifts easier.  Its easier to handle a freezing shift cable.  There is no "clickbox" sticking out in the way of pannier bags.  On the other hand, the P5 is a lot smoother in operation, its likely a bit more efficient, and it doesn't take tools to disconnect its shift cable.

Anyway, Nexus 8 is a good Nihola hub.

The Nihola vs The Snowy Hill

My son is always ready with the snow shovel.

After a snowless holiday season, Oslo finally reached freezing and stayed there between the 11th of January and the 2nd of February, which was three full working weeks.  Strangely enough, snow fell almost every day, ranging from dust to 10cm/4in.

About when this was all starting, I actually went out with a 60cm/2ft level and tape measure, and made a few measurements of the slope that I need to haul my son up, to reach his daycare.  Of course I didn't want to spend too much time looking ridiculous measuring the public path, so I only measured the most interesting spots.  To jump to the numbers, I can now say that I have definitely climbed slopes over 25% with two kids in the box (lets say 50kg of cargo total) on my 15 gear-inch Nihola.  I can also confidently say that a 15% slope is doable with the same load on my 21 gear-inch Nihola (with a Shimano Nexus 8 hub, nothing exotic).  So thats good to keep in mind.  Niholas can do hills.

The more interesting question to a year-round utility cyclist might be how steep of a slope can be managed when its covered in snow.  I've been testing this the past three weeks, but first a little about the hills I've been climbing.  On the way to the daycare, there is in fact a small bit of 25% slope, rising suddenly after a tunnel under a road.  This flattens to nothing in 40m or so, but its a definite problem spot.  After some modest climbing, a 200m stretch that is up to 10% slope starts, then a stretch of 70m at 12% slope, with a measured max of 15%.  Overall > 50m in < 600m with an average slope of 8-9%.  On the opposite side of that hill, without children, I climb/descend 175m in 3km with slopes up to around 15%, and once in this period I also took a long way home, which ended up being un-plowed for 2km averaging 3% slope.  Now none of this is epic on the scale of hills where snow accumulates, but its plenty hard enough, and since I don't see a lot of people doing it, I might as well share what I have observed.  Perhaps people think its harder than it is.

First observation: I can pedal my Nihola some places and conditions where mountain bikes carrying no particular cargo can't be ridden.  I shouldn't be too proud of myself; sometimes it might be faster to just pick up a bike and walk, than grind through the snow on a trike.  But anyway, if a person is intent on bringing their trike with them, it can be done, and it doesn't involve falling over.

This unstable snow caused a lot of trouble for bikers.
The dark mark is where someone had to fight to remain upright.

Second observation: Light fluffy snow on relatively flat ground is not a problem, given appropriate preparation of the Nihola (rear tire type and inflation, weight in back).  If the snow gets deep enough so that the steering linkages or cargo box start dragging, then forward progress becomes markedly more difficult (depending on how heavy the snow is).  The box bottom is about 15cm/6in off the ground, the lowest steering components are around 11cm/4in, and the pedals go down to around 8cm/3in.

This amount of new snow was no particular problem, even with a shifting foundation underneath.

Further observations: A 25% snow-covered slope is in reach if the conditions are right.  For example, on hard-packed snow, when the temperature was -15C/5F, starting from being almost stopped at the bottom, on a Nihola with around 23kg of stuff in front, 10kg of stuff on the rear rack, 21 gear-inches and a Schwable Snow Stud for traction, I could manage.  You could say that the snow conditions were favorable, providing a firm surface for the tire the bite in.  The relatively sparse studs on that tire were likely of little use in these conditions.

The condition of the road surface is of paramount importance.  On the same section the following day, I had a lot of trouble with the other Nihola.  In that case, the snow was fresh (less than an inch), the temperature was more like -5C/25F, I had closer to 37kg in front, 10kg in back, a more impressive Nokia Extreme (26x2.1) rear tire, and 15 gear-inches to work with.  I had to make multiple attempts at the climb, and only succeeded on the less-steep side of the path and with significant tire slippage.  As the days passed, I continued to climb that nasty spot through various forms of snow, and generally higher temperatures, up to icy melting conditions this morning.  In looser snow, this often meant spinning and digging, with very slow progress and sometimes with rolling backwards to use the excavated trench to build a spot of inertia.  This morning with maybe 17kg in front and 6kg in back (I weighed my bag to see), on wet soft ice, I needed a run at it to clear the steepest parts and could make a little progress from a standstill somewhere over (estimated) 15% slope.  I was carting both kids up the hill, and the older one had to walk there.  Three-wheel balance allowed me to thoroughly confirm that there was no way I'd make it with both kids; usually after a run I was sliding backwards with all three wheels locked up.

Here, the rear tire has scraped up snow shavings from a hard-packed surface.

Here we have dug a trench in semi-packed snow.
Heavy load in front, not much on the rack.

With 2-3 inches of unpacked snow on top of packed snow, around -8C/18F, I had to roll backwards a few times on the 20-25% slope.  Its important to be mindful to push rider weight as far backwards as possible.  The 15% slope areas were difficult but steady, lots more pedal turning than actual forward progress.  I set rear tire inflation quite low, which might have helped.  I doubt I could have it without the 15 gear-inches, but rolling the pedals backwards was unnecessary.

I met various forms of snow in these three weeks, from unpacked to hard packed, and with lots of foot-trodden mushy middle ground.  Obviously hard packed is preferable, but when that was not available, I was not able to determine if it was better to drive where people have made a mess, or where the snow was undisturbed.  Lots of slow work in both.

On soft ice, the advantage of 15 gear-inches is reduced compared to something more like 20 gear-inches, because it was necessary to be very careful with the torque, to maintain traction.  On the other hand, having really low gears allows comfortable crawling while waiting for all the kids sliding down the icy hill to get out of the way.  Its best to keep moving, rather than stopping.  Rolling the pedals backwards was possibly essential in really delicate situations, to avoid breaking traction and starting a backwards slide.

I suspect that hauling kids around on hills in the winter is not an activity that is about to go mainstream.

The snow is melting away, and messy.