Going down a steep hill I recently got up to just over 40 mph. I applied both roller brakes, which weren't very effective initially but then suddenly the front brake grabbed, almost locking the wheel (had I not released the brake lever straight away I would have taken a flying lesson). The front and rear brakes are both Shimano Nexus units and the bike is only 10 months old.
I'm going to be more careful next time with front brake application but I'm curious if this is common with hub brakes. Is there anything I can do to prevent a recurrence next time I go down this hill (other than not going so fast)?
I'm going to be more careful next time with front brake application but I'm curious if this is common with hub brakes. Is there anything I can do to prevent a recurrence next time I go down this hill (other than not going so fast)?
I believe if you dump too much energy (ie: brake from too high a speed) into the Nexus roller brakes then you boil the grease? The brake then becomes *much* more effective, and this would correlate with you (almost) emulating Superman.
As for preventing this, well going faster does mean you'll lose more energy to aerodynamic drag. Perhaps regular reasonably sharp braking as you come down the hill? Scrubs off quite a bit of speed, but then lets your brakes cool down for the next time? -- These opinions might not even be mine ... Let alone connected with my employer ...
Going down a steep hill I recently got up to just over 40 mph. I applied both roller brakes, which weren't very effective initially but then suddenly the front brake grabbed, almost locking the wheel (had I not released the brake lever straight away I would have taken a flying lesson). The front and rear brakes are both Shimano Nexus units and the bike is only 10 months old.
The service instructions say:
"When using the Shimano Inter-M brake system, avoid continuous application of the brakes when riding down long slopes, as this will cause the internal brake parts to become very hot, and this may weaken braking performance. It may also cause a reduction in the amount of brake grease inside the brake, and this can lead to problems such as abnormally sudden braking."
and also:
"If braking force is abnormally strong ... the cause might be not enough brake grease, so ask the place of purchase to grease the mechanism with special roller brake grease."
Wiggle sells the grease - 6.99 for a decent size tube. Search for 'brake grease'.
Going down a steep hill I recently got up to just over 40 mph. I applied both roller brakes, which weren't very effective initially but then suddenly the front brake grabbed, almost locking the wheel (had I not released the brake lever straight away I would have taken a flying lesson). The front and rear brakes are both Shimano Nexus units and the bike is only 10 months old. I'm going to be more careful next time with front brake application but I'm curious if this is common with hub brakes.
"The Roller Brakes are probably OK for light duty use in flat terrain, but I wouldn't recommend them for cyclists who ever go fast, or ride in hilly terrain. It's OK for a rear brake, if you don't mind the weight, but I continue to be highly dubious about using it as a front brake on bikes with full-sized wheels."
Is there anything I can do to prevent a recurrence next time I go down this hill (other than not going so fast)?
Fit a better front brake. The roller brake can stay in place if you like, and the lever wired up to something else. The forks will take a dual-pivot caliper if they have a hole drilled in the crown. Mudguard and wide tyre won't be a problem for an Alhonga brake, for example (tyre is deflated before fitting/removing wheel).
"Pete Biggs" <[email hidden]> wrote in message news:[email hidden]... <snip>
Quoted message said:
"The Roller Brakes are probably OK for light duty use in flat terrain, but I wouldn't recommend them for cyclists who ever go fast, or ride in hilly terrain. It's OK for a rear brake, if you don't mind the weight, but
<snip>
It does seem that they are for light duty use (I'm over 100 kg and there are many long steep hills here). The brake performance at high speed was a surprise to me but the explanations offered of the grease boiling/overheating makes sense, especially as the brake seemed to feel rough and grinding at the same moment. I was pulse braking at the time this happened so it's not a braking technique issue. The bike is already of the sit up and beg style so short of a drag chute there's not much I can do aerodynamically. I shall enquire at the LBS about whether a grease gun is required to properly lube the brake or whether the tube comes with a suitable nozzle.
Quoted message said:
Quoted message said:
Is there anything I can do to prevent a recurrence next time I go down this hill (other than not going so fast)?
Fit a better front brake. The roller brake can stay in place if you like, and the lever wired up to something else. The forks will take a dual-pivot caliper if they have a hole drilled in the crown. Mudguard and wide tyre won't be a problem for an Alhonga brake, for example (tyre is deflated before fitting/removing wheel).
Well actually the cheaper model of my bike comes with rim brakes but overall the benefits of hub brakes outweigh the advantage of better rim brake performance (in the dry) for me. What would be a really good design would be a low drag version of a multiplate internal disc design as per motorcycle clutches or large aircraft brakes but I don't know if such a product for bicycle use has yet been developed or attempted. I would imagine the sticking point would be reducing the drag/rolling friction to an acceptable level when the brakes aren't applied. This sort of brake does offer a compact, high braking performance arrangement however - hence their use with large aircraft.
What would be a really good design would be a low drag version of a multiplate internal disc design as per motorcycle clutches or large aircraft brakes but I don't know if such a product for bicycle use has yet been developed or attempted. I would imagine the sticking point would be reducing the drag/rolling friction to an acceptable level when the brakes aren't applied
Wot about disc brakes in a weatherproof cover? (or is that what you said above?)
It does seem that they are for light duty use (I'm over 100 kg and there are many long steep hills here).
Our prayers are with you ;-)
/snip
Quoted message said:
Well actually the cheaper model of my bike comes with rim brakes but overall the benefits of hub brakes outweigh the advantage of better rim brake performance (in the dry) for me.
If it was my bike I'd have some of the benefits of both types - by having a rear roller brake and a front rim brake. Surely that's a good compromise?
I have ridden a bike with a Nexus roller brake. The braking power only seemed adequate for a *rear* brake to me, and only just.
I shall enquire at the LBS about whether a grease gun is required to properly lube the brake or whether the tube comes with a suitable nozzle.
The tube has a shaped nozzle, and the instructions show you just sticking the nozzle in the hole on the side of the brake and giving the tube a squeeze. The grease looks rather thin (having squeezed some out) and heavily loaded with something black (graphite powder? looks like it).
"Ian Smith" <[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
Paul Murphy said:
I shall enquire at the LBS about whether a grease gun is required to properly lube the brake or whether the tube comes with a suitable nozzle.
The tube has a shaped nozzle, and the instructions show you just sticking the nozzle in the hole on the side of the brake and giving the tube a squeeze. The grease looks rather thin (having squeezed some out) and heavily loaded with something black (graphite powder? looks like it).
Thanks, it looks like an all in one ready to go solution. I'll certainly give more hub brake lube a try so I can get back to flying down hills (although hopefully not literally). I dont like all the downsides of rim brakes nor the cost of replacing all the bits reqd for a front disc so will stay with the roller brakes for now with a relube every 6 months or when reqd.
