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Roller brakes: running friction?
On Tue, 28 Jun 2005 05:59:14 +0800, usualsuspect wrote:
the guy in the shop said hub brakes are better anyway. are you saying this isn't true? Depends on what you mean. They don't lose stopping ability in the rain, as many rim brakes/pads do. They last much longer. But in dry conditions they do not stop as well, and there is the weight and residual drag. what about hub gears (nexus 8) vs regular derailleurs (shimano deore)? Same sort of comments apply. They are less prone to damage/fouling/fussiness than derailleurs, but adjustment is critical, and they are less efficient. I use a roller brake and a nexus-7 hub gear on my rain bike. Makes sense for that. -- David L. Johnson __o | You will say Christ saith this and the apostles say this; but _`\(,_ | what canst thou say? -- George Fox. (_)/ (_) | |
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#12
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Roller brakes: running friction?
Alex Rodriguez wrote in
I agree about the disturbingly gradual buildup of stopping power in the shimano roller rear brake (no clutch there, unlike the front). My bike has cantilever bosses, so I kept the 7 spd hub but went back to v-brakes. And that's one less cable to disconnect to get the wheel off as well. The thing is packed with grease inside, and I think that contributed to the rather draggy feel. Maybe it was just due to shedding the weight, but I gained pretty much one gear on the hills of my commute after ditching it (I got the thing in the first place as it seemed a reasonable idea for all-weather commuting in a rainy climate). : In article , says... As another poster observes, you don't get disc brake standard instant stopping with hub brakes but it is more than perfectly adequate. Adquate for what? I have a Nexus 7 and I can grab the brake till it touches the bar and it only slows the bike down a bit. An adequate brake should be able to lock up the wheel. If my bike had cantilever studs I would have gotten rid of this brake. Especially since I just found out the brake weighs over a pound. ----------------- Alex |
#13
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Roller brakes: running friction?
in message , lid
') wrote: what about hub gears (nexus 8) vs regular derailleurs (shimano deore)? Hub gears typically have /slightly/ more drag than deraileurs but require /much/ less maintenance. Consequently for a non-racing urban bike they make a lot of sense. -- (Simon Brooke) http://www.jasmine.org.uk/~simon/ to err is human, to lisp divine ;; attributed to Kim Philby, oddly enough. |
#14
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Roller brakes: running friction?
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Roller brakes: running friction?
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#16
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Roller brakes: running friction?
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#17
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Roller brakes: running friction?
"Clive George" wrote in message ... "Alex Rodriguez" wrote in message ... Adquate for what? I have a Nexus 7 and I can grab the brake till it touches the bar and it only slows the bike down a bit. An adequate brake should be able to lock up the wheel. Apply the front brake sufficiently and it will be able to :-) Seriously, the back brake shouldn't be doing much of the slowing anyway, so being a bit crap isn't much of a problem. Unless the front brake is also crap. (This does not apply to tandems :-) ) or long wheel based recumbents Alex Have you tried taking up the slack in the cable so the lever will not touch the bar? cheers, clive |
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Roller brakes: running friction?
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#19
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Roller brakes: running friction?
Somebody wrote:
i am looking at a ridgeback switch at the moment. i was trying to get one with disk brakes but they're out of stock. the guy in the shop said hub brakes are better anyway. Alex Rodriguez plied again: No, the Nexus roller brakes are quite poor. For a rear brake it is not a big deal. I would not ride a bike that had a front brake that is as poor as the rear roller brakes are. I Me neither, but as it happens, the front Rollerbrake is considerably _worse_ than the rear! Shimano puts a slip clutch into their Rollerbrake front hubs as a putative "safety" feature. Seems a bit bizarre to me that a device that reduces braking power could be considered a "safety feature" though. Some, but not all, Nexus front Rollerbrakes have annoying rattles in the cable linkage. what about hub gears (nexus 8) vs regular derailleurs (shimano deore)? The Nexus 8 is supposed to be better than the Nexus 7. That's true, I own a Nexus 7 and two Nexus 8s. I just LOVE the Nexus 8, commuted on one of them this morning... (I left the Rollerbrakes off of all three of my Nexus bikes, don't need a weak rear brake that weighs a pound and a quarter. I use rim brakes on all three of these bikes. http://sheldonbrown.org/raleigh-competition http://sheldonbrown.org/raleigh-international http://sheldonbrown.org/iro Sheldon "Space Technology: Planetary Gears!" Brown +------------------------------------------------+ | If you don't want your message to get to me, | | insert **NO-SPAM** into my email address. | +------------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide http://captainbike.com http://sheldonbrown.com |
#20
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Roller brakes: running friction?
Sheldon Brown wrote:
Seems a bit bizarre to me that a device that reduces braking power could be considered a "safety feature" though. I have no objection to the concept of modifying torque or preventing skidding. ABS does both and is considered a safety feature. I am only concerned about the implementation. ABS modifies torque if vehicle motion exceeds wheel motion and operates low or high friction surfaces. The Shimano system merely puts an upper limit on torque. Shimano quotes ISO 4120 and DIN 79100-2. This requires a weight of 100 kg and a brake lever force of 100 N. I understand that the requirement is to exceed 2.2 m/s^2 wet and 3.4 m/s^2 dry. Shimano quotes a deceleration capability of 3 m/s^2 for the SG-8c20 rear hub. Magura claims rim brakes can achieve 4 m/s^2 and discs 8 m/s^2. It would be interesting to know the torque or deceleration values for the Shimano front hub. |
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