Overhaul time: Why is My Bike Soooo Sloooow?

henrys-own-nuvinci-workcycles-fr8-1
Almost done; Just a little more Dremel action to make room in the chaincase for the Nuvinci hub’s large shifter unit.

Here is a techie tale of real world, long term product testing and what an enormous influence bike maintenance can have on your cycling pleasure. You may recall that I use my own bike to test components and accessories, usually for a couple years unless something just sucks. Then I just remove it as quickly as possible. If I really like something I just call it “mine” and leave it in place until I have a reason to do otherwise.

About a year ago during a several week cold spell I decided that my own Fr8 was deadly, painfully slow compared to others. But I hate repairing my own bikes so I just kept on riding it through the winter, spring, summer, fall and some more winter until a couple days ago. Nothing was really broken nor made even an annoying peep; I just had the feeling I was pedaling pretty hard while grandmas with flowers in their hands and moms on bakfietsen loaded with four kids glided on past. Was I just a little tired… for an entire year? Cycling on this bike just wasn’t as much fun as our others but usually I wouldn’t notice it and if I did notice I’d forget about it shortly after locking up (or not!) and walking inside.

This is exactly why we exhort you to regularly service your bike, unlike yours truly. A well maintained bike is just nice to ride and a crappy running bike is less so, even if you don’t actually notice it. Why sweat more than you need to? Why feel that click, clack or sloppy drivetrain when you can daily enjoy the pleasure of pedaling along silently and effortlessly. This must be one of the world’s cheapest pleasures.

I assumed the abundant friction in my bike had something to do with the NuVinci N360 infinitely variable hub since that’s its most unusual feature. With the bike in the lift the rear wheel required a good tug to turn and it didn’t spin at all. I was totally wrong about the hub but will get to that later. We’ve discussed the Nuvinci friction thing ad infinitum on the @Workcycles Facebook group. Unfortunately a Facebook group can’t be searched so finding those discussions again would mean hours of scrolling. No doubt Mr. Zuckerberg is snickering this very moment while he employs his own powerful FB search engine to scan the Groups for info about Nuvinci hubs and Workcycles Fr8′s.

I spoke to the folks at Fallbrook/Nuvinci. They assured us that that the cold should have little influence on the hub’s efficiency so there must be something wrong with my hub. A replacement hub was quickly dispatched. It then waited patiently for a half year, for the day that I have both the time and willpower to pull my Fr8 apart, build a new wheel and put it back together. The other day the temperature dropped well below freezing and my rear brake and shifter cables froze. After spinning madly to school and work for a few days in the tiny ratio it was stuck in I declared my bike officially “broken”. The operation could commence. I gathered several other new parts to try and stripped my bike.

With the wheel out of the bike and the rollerbrake removed I clamped the axle in the vise and spun. It spun rather well I must say. I mean this ain’t my track bike whose unsealed, oiled bearing wheels will spin for several minutes before gradually stopping, but the Nuvinci wheel did spin almost as well as most other multigear hubs do. Further, spinning axles with my fingers, I couldn’t detect any difference between the 18 month old, ridden daily and stored outdoors Nuvinci and the brand new one. As far as I can tell this hub is as good as new.

monark-centerstand-workcycles-gr8 1
A fresh, clean Monark centerstand, aka “The Mother of All Centerstands” on the same bike when it sported skinnier tires and a single gear.

What then is dragging my ass down? Could it be the Hebie Chainglider, which “glides” along the chain instead of being attached to the frame? It and the chain running through it were both filled with a gritty, slimy paste of oil and dirt. It was vaguely audible while riding and sounds take energy to create. I decided: Away with Chainglider! I only put it on this bike because I was too lazy to cut up a real Hesling chaincase to fit around the Nuvinci’s shifter interface and the Monark “Mother of All Centerstands”. Actually I’m still kinda lazy; I removed the Monark centerstand and installed another Ursus Jumbo. I’d previously tested and broken one of these but it’s apparently been improved since then. Time to try it again, and very convenient that it just barely fits together with the chaincase.

Fr8 Henry 2012
My bike in the spring with the sludgy Hebie Chainglider still installed. I’m very happy to have a real, silent, frictionless Dutch chain case on my bike again.

Still, I couldn’t believe that either the Chainglider or the filthy (but almost new) chain were really causing so much friction. Spinning the crank backwards the friction was negligible, despite the scraping noises. So the Chainglider wasn’t helping the bike’s efficiency but it also couldn’t have been the root of the problem. Nonetheless a real Dutch chaincase is always better if it fits. After half an hour of Dremel grinding and careful adjustments to the brackets the chain ran through the Hesling case silently and with no friction whatsoever.

Eurobike 2009 14
Shimano Rollerbrakes exposed; The IM80 rollerbrake has a much bigger, sturdier brake unit.

Next stop: Rollerbrakes. The Shimano IM80 rollerbrakes on this bike have performed admirably since I installed them. They stop the bike with authority and have good lever feel too. The braking power was confidence inspiring even while cycling in the steep hills of Brussels with two kids and baggage aboard.

Orange Bike Days-2011 14

Little did I realize, however, that my powerful rollerbrakes were braking ALL the time. Once the rear brake was in my hands it was obvious who the real culprit was; A fine paste of Shimano’s sacred, expensive rollerbrake grease and road dirt filled the brake unit requiring serious hand force to rotate it. The front brake was better but not much. Did I screw them up myself by putting too much grease in them? I don’t remember.

With copious quantities of brake cleaning fluid and compressed air I removed every trace of everything from the brake units. Wonder of wonders they spun almost freely now, rather like the name “Rollerbrake” would imply. No way I’m going to sludge these babies up with that stupid grease again! What else could I put in there to keep them from rusting and lubricate the innards? After a quick inventory of the dozens of little bottles and cans on the Workcycles shelves we decided that a thick, clingy OIL ought to work, even if it violates all instructions, death-warnings and warranties. After all these brakes are fairly well enclosed and don’t see any substantial heat here in cool, mostly flat Amsterdam. The most likely problem I anticipate is that they’ll have to be oiled periodically but whether that means monthly or half yearly remains to be seen. Even generously lubed with oil the rollerbrakes spun quite freely. Back in the bike the rear wheel and brake now spun totally normally.

While I was at it I adjusted the front (dynamo) hub cones: They were waaaay too tight, as delivered from the factory. Now my front wheel spins and spins as if it weren’t filled with magnets and coils. Take that, hub dynamo haters!

henrys-own-nuvinci-workcycles-fr8-rusty-shifter

Of course I also had to fix the problem that pushed me to tear the bike down in the first place: All four cables were removed and given the super special Workcycles anti-freezing treatment. That was when I discovered that the Nuvinci shifter’s adjustment barrels had rusted solid. I just replaced the whole shifter, noting that the new one came with smoother, drawn cables. This is then the only problem the Nuvinci hub has had thus far, an excellent record for a first generation product.

The last update for the day was swapping the older 44T steel crank for the new Sugino 38T forged aluminium crank we’ve begun using. The 44/20 gearing had always seemed a little on the tall side so I figured 38/20 should be about right. Like the Shimano Nexus 8sp hub we fit thousands of, the Nuvinci’s 1:1 ratio is in the upper middle of the range. That is, these hubs have somewhat more undergearing than overgearing, generally quite handy for heavy duty bikes with full sized wheels.

Everything back in place, grips securely glued to the handlebars… and let’s see how it rides. I rolled out the door, pedaled along and Lijnbaansgracht and immediately found myself spinning out in the highest ratio? Huh? I did lower the gearing but not by so much and it was too high to begin with. It was dinner time so I just continued my spinning session for the kilometer home to deal with the gearing later.

henrys-own-nuvinci-workcycles-fr8-chaincase-cutaway
That little silver thing next to the chain is the shifter interface and has to rotate most of the way around the axle – thus the cutaway.

The following morning I hung the bike up again and pulled the wheel to check that the shifter was installed correctly and reaching the full range of ratios. It was. Then I swapped the 20T cog for an 18T making the gearing almost the same as the old (too tall) 44/20. That was a considerable improvement but bizarrely the gearing is still much too low. Once up to speed on any flat road I just twist it into the highest ratio. Even the steepest bridges require shifting down to only about halfway through the range. So I’ll try 17T and 16T when I find them.

The upshot is that I’ve basically been dragging a plow around behind my bike for at least a year. Fixing the brakes, chaincase and front hub wasn’t just a “marginal gain”. It has improved the bike’s efficiency by so much that it can be ridden much faster with the same effort. I can’t be bothered to do the math but it really must be at least a 25-30% speed difference. That’s huge. Faster is funner and easier is nicer… so maintain your bikes folks! It really matters.

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48 Responses to “Overhaul time: Why is My Bike Soooo Sloooow?”

  1. Peter Says:

    Interesting article as usual. Not being a bike mechanic, let me present a slightly different point of view (devil’s advocate):

    - especially with old bikes, as long as you are moving forward, it’s sometimes easier (lazier?) not to repair. I don’t know if it is Murphy’s law, but once you start repairing, new problems appear. I find it better to go as far as possible and then repair everything at once.

    - you are training harder with a lot of resistance. It does not matter if you are wasting energy because you are training. Moving from a rickshaw to even a rusty bike, you feel like you have a turbo on. It’s an amazing feeling.

    - If you are a competitive person, you can always say ‘I am slow because my bike is heavy/has a lot of resistance’ (even though you are just slow).
    - your bike is less prone to be stolen if it is visibly falling apart.

    Very good article as usual. More please!!!!

  2. henry Says:

    Peter.
    Cycling can and should be a joy, not an ascetic, hair shirt activity. Why just barely keep moving forward when for so little cost or effort you can glide along so beautifully?

    For most people city cycling isn’t about training. It’s about getting around as pleasantly, easily, comfortably and conveniently as possible. That includes riding with heavy load such as a couple kids and groceries, riding in adverse conditions, riding when you don’t feel great etc. Anything that makes cycling harder is just a hindrance for the vast majority of transportation cyclists.

    City cycling isn’t about competition. At all.

    I didn’t say to make your bike beautiful. An ugly bike can indeed be a theft deterrent. Fortunately there is little correlation between the beauty of a city bike and how well it rides.

    Thanks for the compliments though!

  3. troy Says:

    I’m interested to know more about what you did to the front hub. I have no experience or knowledge about them; I only now have one on my relatively new Gazelle Cabby. Upon taking possession of the bike, I was surprised at the force required to spin the front wheel. It seemed to me like it requires more force than it should, “even for a dynamo”. I don’t think it even really free wheels after you spin it.

    The rear wheel wasn’t properly seated when I got it either, which has me questioning the abilities of the assembler at the store.

  4. henry Says:

    Troy,
    I only adjusted the bearings by loosening the cones slightly. For the bike mechanic this is a two minute job once the wheel is out of the bike. But like my Fr8, the friction in your front wheel might have more to do with the rollerbrake than the hub bearing adjustment.

    I was checking out a Gazelle Cabby here in our shop a couple months ago and wasn’t impressed by a few points but didn’t look at the assembly quality. I did notice that the front wheel was very badly laced, with a poor choice of rim, spokes and spoking pattern. The spokes were all bent the collective residual tensions in the various components would frequently lead to wheels detensioning and falling apart.

  5. Peter Says:

    Yes, I know, I am the first one to enjoy riding a smooth bike, was just trying to find reasons why a person would NOT maintain his bike properly (some reasons were bad I admit…)

  6. Nick Says:

    Interesting and timely post, for me. In Ottawa, Canada, we are experiencing extreme cold down in the -30s right now. At this temperature my Shimano hub (Nexus 8) seizes up and I can’t shift. I’m stuck in one gear. I also notice increased resistance. I wonder if it is the brakes?

    Have you had any experience with Shimano dynohubs making a screaming sound in the cold? I have two bikes with this hub (including roller brake) that make an extremely loud and continuous squeak but only in very cold temperatures. It’s more like a wailing (I would make this sound too if I were naked in the cold!). This is hard to diagnose because, when I take the bike inside to the work stand, it warms up and the sound stops.

    Is this a common problem?

  7. Lauri Says:

    Nick,
    don’t know how common, but I’ve had exactly the same annoying problem with the Simano dynohub here in Finland. One guy in Estonia wrote he also had it. And yes, there is increased resistance in very cold temperatures, probably in all moving parts of the bike.

    I think your gear cable is frozen. My Nexus 8 has been working even in -25-30 (celsius). Not very smoothly though, the gears change slowly. I changed the cable in the autumn and put some good oil inside the shell(?). Before next winter I’ll have to replace the grip shifter that isn’t working very sharply anymore.

  8. henry Says:

    Nick,
    Lauri is probably correct. Even a couple drops of water between the shift cable and housing will freeze the shifter solid. That was one of the problems I had to fix. Here’s the link to the solution:
    http://www.bakfiets-en-meer.nl/2010/12/08/frozen-cable-time-again/

    And yes, every kind of resistance to motion increases in the cold: Not only do the lubricants in various parts increase in viscosity but there are also many other factors. Just to name a few:
    - increased air density adds wind resistance
    - fewer leaves on trees and reduced vegetation means there’s more wind
    - cold rubber is less resilient
    - air pressure in tires decreases
    - more clothes makes more friction and reduces mobility
    - clothes, accumulated snow and ice adds weight
    - our bodies are expending energy to stay warm
    - etc etc.

    Yes, the screaming dynamo hub is caused by the bearing seals. A spray of silicone will fix it.

  9. Nick Says:

    Thanks for the great responses. The silicone spray worked wonders. It decreased the resistance quite significantly in addition to quieting the wailing.

  10. henry Says:

    Cool!

  11. jim Says:

    ‘the lubricants in various parts increase in viscosity’

    i had the opportunity to cycle in -35 F a couple decades ago, and thought the grease was freezing.

    great post

  12. Jan Verhoeven Says:

    When my FR8 arrived the rear brake was way too tight. The cable was too short. So I replaced it. I’ve been lubing it with Shimano Goo, Galli ball bearing grease but that always leaded to squeaks, peeps and grinding noises.

    Yesterday I dripped in two drops of Atlantic Chain oil. It took a squeaky half hour to get all the sounds out but I ended up with a rollerbrake with much better response and far more stopping power.

    Yesterday evening, after my mail round (I’m a mailman) I laid the bike on its right side, pulled the plug and dripped three to six drops of Shell 15W40 motor oil in the hole, while spinning the wheel. Initial tests with the bike on the center stand showed that this was not a failure.

    Today I rode all day in sleet and snow on very slippery surface. The brake has a proportional response now. All spongyness is out. Pulling the lever is slowing down. Period. I locked up the wheel several times (on icy spots). All sounds are gone.

    A local bike shop once advised me: “Just use any kind of grease. I always do. The goo is just a rip off.” I guess he was right there.

  13. Jan Verhoeven Says:

    Henry says: more clothes makes more friction and reduces mobility

    Apparently you’re still wearing the wrong kind of clothes.

    On my mailround of today I wore

    – a thermo shirt as base layer (the cheapest one from Sengers will do)
    – a PolarTech #100 fleece vest (i.e. no sleeves)
    – a TNF (The North Face) RedPoint jacket
    – my PostNL jacket to keep the wind, rain and snow out and to show I’m one of the good guys… ;)

    On my Trek commuter bike I use thermo shirt, TNF Summit series hard shell with zipped in #100 fleece and that’s it. When it’s real windy I add the sleeveless vest. That’ll keep me comfortable upto -10C. Use the hood! It may look like a sissy, but with the hood on, the jacket performs 10 times better.

  14. Jan Verhoeven Says:

    The dream is over. The rollerbrake is spongy again. Rollerbrakes just suck. I want a disc brake. Already found an adapter for the shimano hub:
    http://cesur.de/gx2/product_info.php?info=p121_cesur-scheibenbremsadapter–shimano-nexus-3-4-7-8-nexus–made-germany-muenster.html

    Now I need an adapted escape hatch that has 74 mm discbrake mounts installed.

  15. Jaap-Willem Says:

    Henry, your story made me check my bikes front rollerbrake (also IM 80). And my conclusions is that I’m not getting old fast, but the brake needs some TLC.
    Do I need to take the brake apart for cleaning or can al the debris be flushed out with a cleaner. I’ve found no information on the www how to take a rollerbrake apart. Can you give me details on that? (If necessary).

  16. henry Says:

    Jan,
    Rollerbrakes don’t suck. But anyway disk brakes are not the answer on the Fr8. Mounting them to the Escape hatch is a BAD IDEA. If you want powerful, crisp feeling brakes and are willing to live with a somewhat higher hassle factor… the Magura hydraulic rim brakes are the best bet. But mounting these on an existing Fr8 is no easy task since it requires brazing the pivots on the frame and fork, and ideally building wheels with rims that have machined sidewalls.

  17. henry Says:

    Jan,
    I didn’t say that I don’t know how to dress for cycling in cold weather. I am a bike racer after all and sometimes (such as today) spend five or more hours in the saddle in windy, subzero conditions. Likewise, being a Dutch postman you’re essentially a sort of professional cyclist. You know the best ways to dress to stay warm with minimal resistance. Most utilitarian cyclists, on the other hand, dress primarily for where they’re going. Aside from avoiding those coats, skirts and shoes that really suck to ride in they just don’t think much or anything about dressing for the ride.

    The point is that many little things conspire to make cycling in the winter slower than in the summer. When you do it a lot you learn to optimize but there’s still no avoiding the fact that cycling in the winter means higher resistance than in the summer.

  18. henry Says:

    Jaap-Willem,
    As you’ve probably figured out from my photos on Flickr we do sometimes take rollerbrakes apart. In theory it’s a “no user serviceable parts inside” component but with some bending of the tabs that hold them together they will come apart. However they’re a bitch to get back together again so I don’t recommend it. I was able to quickly and thoroughly clean my rollerbrakes just by alternately spraying through them with brake cleaning fluid and blowing them out with compressed air.

    One month later and my oiled up rollerbrakes still feel good; no scratchy metal on metal sounds, no apparent friction etc.

  19. Jan Verhoeven Says:

    Still, my rear brake slows down like I was holding a wet sponge to the tire. It doesn’t bite any more. So I swapped front and rear brake levers and now my front brake is on the right side.

    Why is my rear brake so bad? Cannot be the 7 drops of oil. I also tried ballbearing grease six months ago.

    How did you actually degrease your brake? Would it be an idea to spray in WD40 while turning the wheel?

  20. Henry Says:

    Jan, read the comment above for how I thoroughly cleaned the rollerbrakes.

  21. Jan Verhoeven Says:

    Yeah, but I have neither compressed air nor a professional degreaser.
    I do have a few cans of WD40 plus a lot of patience. I reckon the same goes for the majority of people in this topic.

  22. Jan Verhoeven Says:

    Oh, by the way. Nowhere on the internet can you find some exploded view drawings of a rollerbrake. I guess you happen to have some pictures. With some processing in a PAINT like program, you may be ale to fill in the location of the greasing hole and such.

  23. Jaap-Willem Says:

    try this:
    http://www.maths.lancs.ac.uk/~lucy/hobbies/bicycles/shimano-roller-rebuild.html

  24. Brian Porter Says:

    Henry, I wonder if you would be willing to comment on the setup of the BR-IM81 series roller brake. I recently purchased a set of these to replace the BR-IM41 series that came stock on my older bakfiets. I switched out the front brake yesterday but was dismayed to find that when I set up the BR-IM81 as instructed by Shimano (i.e. 109 mm cable length between the cable anchor and the cable adjuster and cantilever/standard throw brake levers), I can bottom out the levers without slowing the bike much at all. Furthermore, there is no play in the lever – it just feels like a steady mush as I pull down. This is in contrast to the way it felt when the BR-IM41 was installed which did have 15 mm or so of play in the lever before it really engaged.

    I spent awhile on the floor of my garage inspecting the brake and thinking the situation over. It seems to me that the BR-IM81 requires substantially more cable pull to engage than the BR-IM41 series. The performance when setting these up per Shimano’s instructions is obviously inadequate. So it seems to me that I have two options: 1) set up the brake so that it is semi-engaged all the time, so that when I pull the brake lever I actually get some stopping power, or 2) switch to V-brake levers that will provide substantially more cable pull. I did try the first way, shortening the 109 mm distance to 80 mm or so, and I got ok braking power that way but the wheel spun very slowly. So I’m inclined to try V-brake levers; I have some on order.

    Do you have any thoughts on this? Do you use V-brake levers for the Workcycles bakfiets that you sell through your shop? On your FR8, is your roller brake semi-engaged all the time or is it strictly off? By switching to an oil lubricant, can I set up the brakes to be semi-engaged all the time without suffering from terrible rolling resistance?

    I wish I could bring my bike to your shop for a professional assessment. Thanks for any advice you might be able to provide at a distance. Best to you and your family.

  25. henry Says:

    Hi Brian,
    Yes, you actually answered your own question. The old type rollerbrakes were meant for standard, high leverage brake levers and the new series (IM45, 55, 80, 81 etc) require V-brake type levers. That will fix the problem.

    So far one month with heavy oil in my own rollerbrakes and they still work great, but as I noted in my post this might only be appropriate for our local conditions. In a place where the brakes really have to absorb lots of heat it could even be dangerous. I would find it surprising if Shimano recommended the high temperature grease for absolutely no reason at all.

  26. Ike Says:

    Henry, in light of this post, and aside from the required modifications to fit the Chaincase with one, how do you feel about using the NuVinci 360 hub on Fr8s now, as opposed to the Shimano Nexus 8s or other hubs?

  27. henry Says:

    Hi Ike,
    I like the Nuvinci for its super smooth feel, being able to change the gear the tiniest bit to get it perfect, and for the total lack of hassle factor. Set it and forget it; You never need to adjust it.

    On the other hand I still feel like it’s a little less efficient than the Nexus 8, at least compared to 8′s more efficient gears. Compared to the fourth gear of the Nexus 8 in my wife’s bakfiets I’ll take the Nuvinci any day.

    The real question is whether it’s worth the extra dough to somebody.

  28. Jan Verhoeven Says:

    As you know, I would live to see a FR8 with either Pinion drive or Rohloff drive…. I need lots of low gears. And the thought of a gearing system of which I can change the lubricant myself is a very fine thought.

  29. Jan Verhoeven Says:

    I would LOVE to see, not LIVE to see.

  30. Brian Porter Says:

    Henry, thanks for your advice re: V-brake levers. I’ll give them a try and report back.

    I’m in Seattle, which is plenty hilly and wet, so I’ll plan to keep using the special Shimano grease. When it comes down to it, I’ll accept slightly more resistance if it buys me a bit more braking power when I need it.

    And yes, the 4th gear of a Nexus-8 is nasty. I try to skip it entirely when I’m traversing the gears.

  31. Jan Verhoeven Says:

    Hmm. I definitely like 4th gear. It’s my favorite. 5th Gear is a bit clunky. I guess it’s a matter of taste and terrain.

  32. Anonymous Says:

    Had a flat front tire today. My first puncture in two years (approximately 9000 km). After patching the tire I removed the front IM80 rollerbrake (just one nut). Placed it on a tin can with the big hole upwards and flushed a few times while spinning with petroleum with a bit of engine oil added. Works wonderful. After drying I lightly oiled the brake, adjusted the Dynamo hub (also to tight) and reassembled the wheel and brake. Result: A free spinning wheel and a smooth working front brake. So no need for professional equipment. If I knew it was that easy I had done it in summer instead of a cold shed in winter. Henry thanks for the inspiration!

  33. Jaap-Willem Says:

    Sorry, Anonymous was: Jaap-Willem

  34. Jan Verhoeven Says:

    What do you mean with ‘the big hole’? The grease port is the small hole I guess. For the rest the only holes are those for the axle to go through?
    Did you flush with the grease port pointing up or down? How about flushing in site (for the rear wheel)? Would it be appropriate to just pump in half a can of WD40 with the wheel in place?

  35. Jaap-Willem Says:

    Jan,
    When you have removed the wheel from the bike you only have to remove the nut which holds the brake (spanner 17). Dead easy! You can than remove the brake. The axle hole is axle size on the outside and a lot bigger on the inside. That’s where you can see a part of the actual braking mechanism. Place the brake on a tin can with the small hole down and start cleaning by pouring your favorite cleaner in the brake while rotating the braking mechanism. The in the tin can collected cleaning fluid can be cleansed with a funnel (cut of plastic bottle) and some cloth to be used several times. I quick dried the brake with an electric paint stripper and then applied some oil. I don’t recommend cleaning in situ because there is a risk of flushing out grease of your wheel bearing. And besides everything will be covered in greasy sludge. When removing the front wheel please don’t forget to disconnect the dynamo hub (if your bike is fitted with one). The whole procedure took me less than an hour.

  36. Jan Verhoeven Says:

    Today I shot two short bursts of WD40 in the mounted (rear) wheel. Braking is already bad, so I cannot loose much. Gave it a spin, during the bursts. Tomorrow I’ll see what it did. Stationary tests showed no adverse effects.

  37. Brian Porter Says:

    Follow up on upgrade from BR-IM41 to BR-IM81 (see my comment dated February 23rd): After an upgrade to V brake levers and shortening the cable length of cable between the anchor and the adjuster, I was able to get extremely good braking power on my new front brake. Too good, in fact. Yesterday coming down a very short hill near home, as a test I braked hard just with the front brake. Unfortunately I locked up the front wheel (apparently overcoming the Power Modulator clutch in the front hub), putting the bike into an unrecoverable skid. Of course my child was not in the bike when I was doing this, but I did crash pretty hard, flipping the bike onto its side and resulting in a broken bone which will keep me off the bike for a few months. Worse is the psychological impact though. Recognizing that my crash was due to user error, I’m pretty afraid to put my son back in the bike as long as a crash mode like this is even a possibility. So I’ve decided to switch back to the much weaker BR-IM41 for the front wheel which was immune to wheel lock up. My braking distance will go up again, but this is the lesser of two evils in my mind.

  38. Remo Peter Says:

    So Brian, you prefer crashing into an obstacle rather than risk a skid, bad solution IMHO. Power modulator is part of the hub, not the brake. So the failure was there. Maybe it was stuck because never challenged by the weak IM41.
    What I don’t quite get is why people order new brake levers for V-brake cable pull, when you can simply change the Nexus brake levers’ mode (remember that paper flag hanging on all new levers? It’s meant to be conserved for reference).
    Remo, Zürich

  39. henry Says:

    Brian,
    Somehow I never noticed your comment until Remo added his answers.

    I’ll agree with Remo though somewhat more tactfully. It’s much better to have the braking power and learn to modulate it than to simply not have it available. You locked the brake up with the bike empty, the front wheel having but a few kg load on it. Add the kids and stuff and you’ll both need much more braking power and also have the front wheel traction to use it.

    The Power Moddulators are simply a mystery to us. Yes, we understand perfectly well how they work but they do seem to be as inconsistent as the power of the roller brakes they’re meant to modulate. I’ve never done any serious research into them but it seems likely that the torque required to spin the modulator unit is lower than the torque needed to lock up a 20″ front wheel with almost no load on it.

    Despite their various shortcomings there is one thing that rollerbrakes never are: Grabby. Rollerbrakes always brake very progressively.

  40. Dennis Says:

    Related: I have a new Kettler Berlin Royal…a beautiful but seemingly impractical bike, because both gearing and rolling resistance seem quite high. With the dynamo, roller brakes, very large diameter low-pressure balloon tires, and considerable weight, it is simply hard to keep the bicycle moving (I can’t stop pedaling even where plainer bikes can coast), and the inexplicably tall gearing makes it worse (you will never get to 8th gear in its Nexus hub, but it could certainly use a ratio lower than its 1st gear.) How can I know the brakes or dynamo aren’t dragging? What is the best/simplest/cheapest way to get lower gearing?

  41. henry Says:

    Dennis,
    Your Kettler is a pretty bike; I’m looking at a picture of it online. Interestingly they’ve changed the specs a lot since yours was made. On their site the bike now has belt drive and disk brakes.

    You can try a few things to reduce your bike’s rolling resistance:
    1. Check the rollerbrakes first. You’ll need to remove them from the wheels to see whether they spin or drag. One of my WorkCycles colleagues has worked out a procedure for cleaning and adjusting the new series rollerbrakes. They work much better afterwards. I’ll ask him to make some photos and instructions so I can put them online. I think a lot of folks will be grateful for the info.

    2. Set the cable tension of the rollerbrakes quite loose to ensure they don’t drag slightly. To do so you need to have brake levers with lots of cable travel and this is a common mistake made by manufacturers. Some brake levers have to cable pull settings and can be adjusted.

    3. Make sure your hubs bearings aren’t tight. Shimano usually ships their hubs adjusted much too tightly.

    4. Make sure your chain isn’t too tight. Even at the tightest point in the rotation it should never be pulled taught.

    5. Make sure sure the bottom bracket spins freely. Many inexpensive bottom brackets have lots of friction. Sometimes just making the left cup a little bit looser can help a lot.

    6. Get rid of the brown tires. Yes, they’re called Schwalbe Big Apples but actually the brown and white ones are an inexpensive version made for manufacturers to fit as original equipment. The black ones are the better “Performance Line” tires that roll and grip much better, and last longer too.

    To lower your gearing it’s usually easiest to fit a larger rear cog. Just make sure it fits within the chainguard.

    Good luck.

  42. Dennis Says:

    Wow! Thank you very much, all excellent advice!

  43. fab Says:

    here is an article verifying the “nuvinci friction thing” and also the infamous nexus-8-speed 4th speed inefficiency.

    http://fahrradzukunft.de/17/wirkungsgradmessungen-an-nabenschaltungen-2/

    unfortunately in German only.

    i wonder if the nexus premium 8 speed would be an improvement.

  44. Ryan Says:

    Hi Henry,

    Sorry if this is a little off topic.

    Can you tell me if all black schwalbe tires better performing than the cream or brown versions?

    I have ordered a fr8 from a uk distributor with cream fat franks, should I change to black big apples or big bens for better performance?

    I will have an 8 mile commute each way so might be better to focus on performance rather than looks.

  45. henry Says:

    Ryan,
    Actually we haven’t fitted Fat Franks of any color on Fr8′s since about 2009 or 2010. But yes, it is true that the black tires are better. Schwalbe and the other tire makers only make their better city bike tires in black. Even though the white, brown and grey tires might be called “Big Apple” or “Fat Frank” they’re not actually the same tires as the black ones. For example the black Schwalbes are part of their “Performance Line” while the colored ones are “Active Line”, basically cheaper tires meant to be installed by manufacturers.

    But many customers just want colored tires so we oblige them. The Active Line tires aren’t bad, but they’re just not as good as Schwalbe’s better tires. They’re heavier, have less grip, and don’t last as long.

    To make a long story short: Unless you really have to have colored tires on your bike, get the black ones.

  46. Ryan Says:

    Thanks for the response Henry, I will email the company and make sure the bike is fitted with black tires.

  47. Aslak Says:

    Henry, wouldn’t the Ursus Hopper be a better alternative than Ursus Jumbo, since the Hopper is steel and thus would break slowlier (and safelier) than the aluminium Jumbo? Granted, it has a 50 kg weight maximum compared to the Jumbo’s 55 kg, but the possibility of detecting a crack in the stand before the bike and its precious (human) cargo topples over surely would outweigh that difference?

  48. henry Says:

    Aslak,
    We’ve tried a bunch of Ursus Hoppers (I didn’t know it’s name but I assume you mean the cheaper, steel version of the Jumbo). They appear to be strong and will probably be reliable. On the other hand they’re rather wobbly and don’t give a rider a feeling of confidence that their bike and precious cargo will remain standing.

    So no, the Hopper is also an OK stand but not a winner.

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