Wednesday, May 6, 2015

Shimano BR-IM80-F, BR-IM50-F, BR-IM45-F

Its been most of a year since I wrote anything.  Life goes on.  I've been doing lots of commuting on an official Danish-name-sticker bike, straight bar, fenders, cargo rack, lights, gear hub, etc.  Its got a Shimano roller brake in front, attached to a dynamo hub.  This is lovely except that it isn't much good for stopping.

I noticed some years ago that more impressive-looking roller brakes were available.  My bike had a BR-IM50-F.  I wanted one such as a BR-IM80-F, but I could find none for sale.  None online, none in bike shops.  Generally they were not even available on bikes in Denmark or Norway.  I had bike shop owners argue with me about whether one would even fit my bike.  I had people say it was all the same, no point in switching.  I had noticed that http://www.workcycles.com sold lots of them, but they didn't really do small part orders.  Then, I actually went to Amsterdam.  I even had to go to the workcycles shop twice to get through to a mechanic without too much waiting.

So, now I had a BR-IM80-F in my hands.  In my carry-on at the airport even, by accident.  That got a raised eyebrow.

Anyway once home, I performed the swap.  Possibly the easiest part swap this side of a pedal with greased threads.  Take off the wheel, apply a 17mm (I think) deep socket, change the shift cable to a new-style cable (had one laying around), done.

So did it improve braking performance?  No.  Not in any noticeable way.

Here I have laid out a BR-IM50-F, BR-IM80-F and BR-IM45-F with their business sides exposed.  The two newer ones appear to be identical except for the cooling surface, and the older one is just damned dirty, also possibly a little worn.


So hopefully by writing this down in the sight of a search engine, others can be informed.  These roller brakes are generally not so useful on hills, and getting a "bigger" one doesn't help.  I have another bike which, like the one I just modified, has only the potential to mount hub brakes.  On that bike I mounted a Sturmey Archer XL-FD (a 9cm drum brake hub), which fits perfectly, brake arm and all, and its stronger though perhaps a little more temperamental.  (Niholas use the 7cm version of that drum brake.)  Going the Sturmey Archer route does appear to require building your own wheel though, not a big supply of pre-fab wheels built on drum brake hubs.

4 comments:

  1. Hello,

    recently purchased an older Nihola 2nd hand. It needs some work and I was wondering about some things:

    1. Have you tried fitting 1,75 inch front tyres? Is there clearance? The reason I ask is because Biltema sells puncture resistant, 20 inch tyres pretty cheap but they're 1,75 inches wide.

    2. What do your brake levers on the front tyres look like? They must made of crap steel because mine are totally rusty.

    3. What is the max dimension of rear tyre? Was thinking of fitting smth with a bit more traction for the winter.

    ReplyDelete
    Replies
    1. 1. The standard front tires are 20x1.75, probably be able to fit 20x2 but bending the fender might be needed, and there isn't a whole lot of clearance when steering tight. Make sure to get good front tires, they seem to puncture more easily than the back one.

      2. My brake levers look fine, but also my niholas do not usually sit out in direct rain, and I've never scratched up the levers.

      3. I have a 26x2.15 knobby winter tire which works in back, but clearance is tight, so the fender, wheel and tire need to be set in place correctly to prevent rubbing. (Nokian/Suomi Extreme)

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  2. Update:

    #1. Bought Biltema, 1.75x20 "Flatfighter" tyres and combined them with their house brand of slime filled tubes. Not as good protection as the Marathon Plus perhaps, but so far sufficient. And cheaper.

    #2. Original marathon tyre still on in the back. Found, to my amazement, that there's absolutely no extra clearance whatsoever. When I inflated the tyre to 4 bars (rated to 4.5 I think) I could hear it slitghtly scraping the frame or mudguard somewhere. Maybe that's because I'm 90 kg, but as you said, there's very little clearance. Don't really ride at any speeds so removing the mudguard is an option.

    ReplyDelete
    Replies
    1. Hmm, check if you can adjust the rear mud guard, the stock tire should have ample room all around back there. Also make sure it is set straight in the dropouts. It can be problematic with the wheel being pulled forward on the right side by the chain. To combat that, I keep the axle threads free of dirt, then lightly grease them, and turn the bolts to a "sufficient" torque.

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