FitNord Rumble 300, 2022

 

the FitNord Rumble 300 ready for action

Cargo trikes/bikes are handy, but there are more efficient ways to transport just yourself.  Our starting point was Danish-style straight-bar bikes, beasts of burden, one per person.  Then there is a cool old bike at the fleamarket, then you need a bike to stand at a train station, then you need a bike while you fix another one, an e-bike would help, a fatbike looks fun, etc.  Somehow over the years we ended up with 10 working adult bikes plus two niholas.  (I'm a geek, almost all the bikes are substantially tweaked.)

Fatbikes are interesting.  If you don't know, they have tires 4-5 inches wide (lets say 100-120mm) and are usually sort of old-school MTB is design.  A bit upright but not too much, comfortable to sit on for long periods.  (There are "cruiser" fatbikes, but those don't look like serious transport.  YMMV.)  One fatbike application is some mix of mountain-snow-exploration-biking, so a good number of fatbikes come with all the mounts for fenders and racks, and without flashy nonsense like a suspension fork.  Basically, its easier to find a fatbike to set up as a no-frills commuter than a MTB.

In 2023 I bought a used (and inexpensive) fatbike and built it up with a Shimano Alfine 8 hub, permanent lights, rack, and full fenders.  Great bike, been riding it to town all winter, worth a blog post.  This contributed, along with a snowy and messy winter, and the near-failure of an e-bike ("snowy and messy winter"), to a situation where we were open to trying an e-fatbike for getting to work.  Also this coincided with a local-ish bike brand putting their e-fatbikes on a substantial almost-spring sale.  So now we have a FitNord Rumble 300 from the model year 2022, in 2024.

Let us begin with the company (FitNord).  They are based in Finland, but there is no doubt that a lot of the product is straight from China.  This is both good and bad.  The good part is a lot of bike for the money, especially at those sale prices, the bad part is that some elements are done to a minimal standard.  I guess the Finnish part is what gives us a purposeful fatbike ready to mount the full-coverage fenders (purchased separately), the rack (also purchased separately), and even equipped with a solid kickstand.  Wowa.  (Their sales materials could have been better, I didn't even know there was a kickstand, but I was super-pleased when I laid eyes on it.)  IMO this right here is a huge recommendation: its a total commuter e-fatbike, period.  Beyond the basics, many parts have been done very well.

There were a couple of quality issues, and I'm fortunate to have some competence dealing with them.  First, the wiring for the "e" part of the bike.  Whoever pulled those wires just didn't care.  They were laid so that the thin inner wires were exposed to rough-cut edges on the frame, and also they were hanging out (sleeved) under the bottom bracket unnecessarily.  I fixed this with some light disassembly and cable-pulling.  Also I suspect the wires at the top were arranged so that rainwater could run down them into the connectors, so I squeezed in a big blob of bathroom silicone where the sleeved cables passed through the frame (internal, not visible from the outside).  I literally began my ownership of the bike with disassembly and improvement, before turning the power on.  The cherry on top is a doggy-bag I electric-taped to provide a rain cape over the top of the battery and/or power connector, so that the area stays a bit drier.  Although the controller itself is up in the frame where it ought to be dry, the various cable connections downstream of it seem at risk of corrosion, if neglected.  The next flat tire a fatbike gets around here, the failed tube is going to yield a fancy new rubber rain cape.

cable needlessly exposed at the bottom, as delivered

the cable sleeve stops a bit early, as delivered

wires in a risky configuration, as delivered

cables pulled through after the rough-cut edges were sanded down

The front hub also seems to be cheaply made.  The disc rotor rubs alternatively on the inside and outside of the brake pads, at this point I assume it is because the hub isn't machined straight.  This cost me one rotor, because at first I thought the rotor was bent in shipment, and I proceeded to bend it up even more.  Then I bought a new one, and refrained from bending it.  The current situation is that it still rubs, but the massive winter tires are so loud, nobody can hear it.  Also the rubber bearing seals on the hub were awful, at least one started to squeal right away.  I ended up taking out the bearings, cleaning it up, and packing lovely washout-resistant grease everywhere, also around the seals.  The one bearing race looked almost a bit damaged, as it a bit corroded, who knows.  I'm not a total pro on cup-and-cone bearings, but I think they had over-tightened them, as they were not smooth when turned by hand.  I certainly felt very sorry for my cone wrenches trying to undo the locknuts, holy crap.  There was probably sufficient grease from the factory, anyway, so thats good.

I would also rate the battery cradle as marginal quality (don't bash it around!), the seatpost seemed unusually happy to slide down after getting the customary layer of grease on it (to prevent it seizing), and the pedals are cheap (but functional).  At risk of triggering OCD problems, the drive-side pedal appears to be somewhat farther from the centerline than the non-drive-side.  (I don't feel the difference, and am not going to tell the lady about it.)  The battery also strangely extends beyond the frame only on the non-drive-side, but it works out fine.

Proceeding past the attention-to-details problems above, there is good news.  This thing ate up a 26x4.2 45Nrth Wrathlorde tire in front, a 26x4.2 45Nrth Dillinger 4 in back, huge full-coverage fenders (from Classic Cycle in Germany) and a XLC RP-R15 rack.  Everything fits nicely without any risk of rubbing, although the fender and rack did compete a little for access to the frame mounts.  The support for the front fender passes right by the brake without needing to be bent.  The rear tire couldn't have been too much larger before meeting the frame, but the front had more space in the fork.  The lights that came with it are pretty usable for commuting (and not the cheapest thing they could have found), though we added one more light front and back.  We even got a Reelight SL520 front blinker light installed, which isn't always easy with fatbike-scale frames.  Incidentally, the front wheel appears to be built somewhat asymmetric, making it easy to mount the Reelight generator on the drive-side front spokes.  Another odd feature is that both wheels are 36 spoke, unusual for a fatbike (or MTB) but probably a great idea for a working bike.  We also swapped the straight bar to a curved one for ergonomics, and put on nicer grips.  Anyway, this thing is now set up a lot like a proper Danish pendler bike, just with tires that are 2.5X wider ... and knobby.

rear tire clearance with 26x4.2 Dillinger 4

The Rumble 300 has an 8-speed derailleur setup, with a substantial-looking chain on it.  The screw pinching the shift cable wasn't even tight out of the box, but its just standard derailleur adjustment to get that fixed.  The motor is in the rear hub, the label is Techdrive.  The name is basically un-Google-able.  I assume that its some label stuck on a widely-sold product from some substantial Chinese manufacturer.  The axle is bolt-on, very much the opposite of "quick release", a plus for anti-theft.  When ridden, it works well.  There is a torque sensor that very rapidly notices when the rider wants to move, and the assist levels are pretty good.  I did not notice any particular drag from the motor.  The battery matches the spec published for the 2023 model rather than 2022, and it seems to have been properly handled while sitting in storage, because it delivers great range.  (Does over 50km in below-freezing temperatures, on imperfect paths, running studs, soft tires, on hills, with useful assist.)  Functionality overall is a huge success, I can't think of anything that could reasonably be improved.  We specifically did not want a model with a center-mounted motor.  Partly because that costs more, and also because it would mean more stress and failure potential on the chain, and also IMO a center motor is more exposed to water spray or just plain submersion.  (The part about submersion of the motor is not only hypothetical, the e-bike that started having problems this winter had actually been taken through a flooded river this past summer.  Not to be repeated.)  I don't particularly like these derailleur geartrains on bikes that are supposed to be beasts of burden.  Ideally you'd have a center motor with a big robust gear hub in back, but the market doesn't do that right now (short of Rohloff of Kindernay).

The range of gearing could be a limitation.  It would be very unpleasant to get up our hill without assist, and even with assist, if there is heavy snow to fight through uphill, its going to heat up rider and motor both.  Fatbikes BTW are not especially easy to ride in unpacked snow, because they are going to squash a big path through it.  The wide tires might however make the journey possible, offering both stability and traction.  Its untested as of yet, but I suspect at the lowest assist level, that the bike will avoid applying uncontrollable motor power in situations where forward progress is a challenge.

Anyway, this thing is a heck of a beast of burden.  Probably summer is not its ideal season; we intend to run a cheaper skinny-tire summer e-bike instead.  But this winter has offered a lot of opportunities for a fatbike to do its thing.  Its snowed a good deal, its rained, its melted, its re-frozen into every conceivable shape and consistency.  Surfaces which are not smooth, or which are not stable, or which are icy.  Ruts and edges in ice, iced paths under water.  Big tires are excellent at all that, run them a bit soft to absorb the smaller texture, to stay on top of shifting snow, and to spread out to find what grip is offered.  There is a potential for the front tire to "plane" on top of snow if ridden too fast into too much semi-dense snow, which results in a loss of steering control, so the bike isn't going to enable heroic monster-trucking so much as it offers improved safety margins, and comfort, when used sensibly.  Just a part of getting to work.

Thumbs up.

two commuter fatbikes (the Rumble 300 was still nearly stock)

 

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.

Shimano Nexus in the cold

I've been a committed utility biker for at around 15 years now, probably every one of those years with freezing temperatures.  Freezing or sluggish shifter cables on gear hubs are a recurring nuisance that even 15 years of experience hasn't fully eliminated.  It is, by the way, always the cable that freezes.  If you have water in your hub such that it can freeze, its going to end badly.

The old hubs with shift boxes sticking out from the axle end are hopeless, IMO.  (For example the old SRAM P5 or S7, great hubs with shifters totally unsuited to winter.)  There are also some hubs that survive it all pretty easily, for example Rohloff, in my experience.  Most hubs though are from Shimano, or shift in a similar way, with one cable which you pull one way, and the hub pulls the other.  A component on the drive side of the hub rotates according to what the cable demands (and what the return spring can achieve).  These are the shifters that are worth writing about.

I have nailed down the ritual of getting water out of the cable housing.  Ideally a person has to do this just once in a year, or less.  Take the bike (or trike!) inside and melt it off (ideally overnight).  Disconnect the cable from the hub (doesn't take long if you know the motions), pull the cable out of the "cassette joint", take some toilet paper around the cable end, and hold this bundle in the end of a vacuum cleaner hose (running).  This pulls water out pretty well after a short time, which can be easily demonstrated with a bit of before-and-after testing in the cold outdoors (if you have time for playing around).  I used to use the vacuum to pull through some tri-flow oil, but in the end I don't think that achieved anything, might have even made things gummy.  I have also greased the cable as it is being inserted into the liner, again without any clear results.  If there is a rubber accordion at the cable end, I cut off the tip and pack it with grease.  (Those accordions not only fail to keep out water, but they potentially get wrapped around the cable pulley and throw off the shift points.)  I pack grease in everywhere as the cable is re-assembled, and then re-attached.

To clarify a bit with photos, here is the "cassette joint" for 4 hubs.  This component holds the end of the cable housing, so when the cable is pulled through the housing, a component on the side of the hub is compelled to rotate.

  CJ-8S40 on Nexus 8 SG-C6001-8C 
19t sprocket

  CJ-8S40 on Nexus 8 SG-8C31 
24t SRAM sprocket

 

 

  CJ-NX40 on Nexus 7 SG-C3000-7C 
24t SRAM sprocket

  CJ-8S40 on Nexus 8 SG-C6010-8R 
19t sprocket

 

note the accordion on the cable

Here we have some photos of one of the hubs where the rubber accordion has for some reason stuck to the cable in such a way that it pulled around the rotating component, and resulted in less rotation for a given cable movement.  This then resulted in the hub not quite finishing shifts correctly in the higher gears.

the accordion should certainly
not get pulled like this

A cable prepared in this way (vacuum and grease-packing) does shift between lowest and highest gear at temps well below freezing, the only trouble is that the spring in the hub may still return rather slowly.  Maybe one second behind the shifter motion.  This slow return sets in gradually as the temperature drops, which seems like grease or oil thickening, but not all my hubs show it.  In addition to the cable, there are internal hub components that need to move, as well as external surfaces that need to rotate past each other.  These surfaces may be exposed to for example chain lube, road salt, grit, and all that the outdoors can offer.  It may therefore be a combination of thickening lubricants, dirt, and moisture.

There is a test that can be performed to discover the approximate location of whatever shifting problem you have.  Its simple: while your cycle is standing outside nice and frozen, you take a 2mm hex key, plug it into a little hole (made for this purpose) on the cassette joint as shown below, and rotate the thing in the opposite direction that the cable pulls.  (You can try both ways, it works only in one direction.)  If it rotates easily (understand that there is a spring at work) then you know the cable is your problem.

One note before proceeding: most of these Shimano hubs are "default low" which is to say the spring pulls to the lowest gear, and without any cable at all, they go to 1st gear.  However apparently at least some Alfine models are the opposite... "default high".  In the photo above, on a regular Nexus 8, this means you can rotate the hex key downwards, and not upwards.  The following text assumes the hub pulls towards 1st gear, as most do.

Separate from the exact cause, its possible for the hub to simply refuse to shift down to 1st gear.  In this case, you can stop and use a thumb to manually push the rotating component forward, pushing towards the top edge.  The cable, running along the bottom edge, is then pulled through the housing to the position indicated by the shifter.  This is a good idea if you are about to start a serious 1st-gear climb, and want to be sure things are actually engaged.  (This is of course annoying, so good to fix.)

When downshifting is sluggish, a rider who is aware of it, and disposed to care about mechanical things, will give the shift a moment to complete, and do fine.  Sometimes downshifting twice, and then once back, will provide good feedback about shift success (or the lack thereof).  An experienced rider can often feel in the shifter if the resistance and travel suggests a good upshift.  Shifts to higher gears are (generally) reliable, because your hand overcomes the resistance better than the return spring does.  When downshifting, if the return spring isn't strong enough, you end up pushing the cable towards the hub, which works somewhat better than pushing rope, but not a lot better.  So its the downshifts that are most likely to give problems.

As you might have guessed already, a Shimano gear hub requires correct instructions from the shifter, or it works poorly.  The indexing for gears is all in the shifter.  The rotation of the cable-pulled rotating component on the hub is perfectly smooth, without any sign of what positions are valid.  The shifter can therefore show numbers that are not entirely in agreement with what the hub is experiencing, and cold weather is a big culprit when it happens.  There is an adjustment mark to check shifter-hub agreement, but that is only one point in the cable travel.  Therefore, in cold weather, if your hub has difficulties holding a gear, suspect that not all is well with the cable.