Brake blocks

[Old Timer]

My Evans has a cantilever front brake (the type where the brake cable comes down from the stem and connects to another short cable and pulls it up central) Suppose that`s a centre pull

Anyway, on the original ali wheels the front brake was about as good as it gets. Now on the double skinned stainless hub wheel that came with the conversion it`s not good at all. I gather it`s just skidding on the shiny surface. I`ve realigned the brake blocks to about the best but although it`s better it isn`t perfect.

I`m looking for some new brakeshoes with blocks and can`t seem to find a listing for soft rubber. I`m not worried about quick weardown as I don`t do that many miles. I`ve even considered ruoghing up the rims a bit but they are the type with a number of grooves running around them.

anyone else had similar and did you solve it?

Dave

 

[flecc]

Chain Reaction Cycles claim to stock soft pads for cantilevers Dave, I've seen a mention of Ritchey's red soft compound pads.
.

 

[Old Timer]

Chain Reaction Cycles claim to stock soft pads for cantilevers Dave, I've seen a mention of Ritchey's red soft compound pads.
.

Thanks Tony, I`ll go now and take a look

Dave

 

[Old Timer]

Chain Reaction Cycles claim to stock soft pads for cantilevers Dave, I've seen a mention of Ritchey's red soft compound pads.
.

The Ritchey ones I wanted were out of stock so I purchased two other types and I`ll let you know how they go

Thanks

 

[NRG]

I fitted some Avid blocks to the Alien that worked very well...

 

[Lloyd]

What rim do you have on your new wheel?

 

[Old Timer]

What rim do you have on your new wheel?

I don`t think there are any markings/names on it.(I`ll check it) it has one black ridge running around it and the rest of the area is covered in fine grooves.

 

[Lloyd]

Have you thought about maybe upgrading to V-brakes? They are much more powerful than centre pulls. The only downside is having to replace the levers also (they require a special cam feature as they pull so much cable). Are your gear/brake levers integrated? If not it is a simple and cheap enough upgrade.

Shimano or Avid are the better performing brands in general.

The pads have a greater contact area as they are longer, and in general they feel much more progressive than centre pulls.

Prices should be in the region of £26 a set of cheaper shimano's, plus a set of levers from around £20 for the pair.

 

[Old Timer]

Have you thought about maybe upgrading to V-brakes? They are much more powerful than centre pulls. The only downside is having to replace the levers also (they require a special cam feature as they pull so much cable). Are your gear/brake levers integrated? If not it is a simple and cheap enough upgrade.

Shimano or Avid are the better performing brands in general.

The pads have a greater contact area as they are longer, and in general they feel much more progressive than centre pulls.

Prices should be in the region of £26 a set of cheaper shimano's, plus a set of levers from around £20 for the pair.

Just had a look at the rim, it`s like most of my E bike rims, a deep black grove with many small grooves either side (this is the default alien front wheel conversion) Brake levers have the micro switches so not straight forward.
If the grooves were sideways on then I could understand that they might give more grip or if the grooves were larger the brake blocks might just wear into them but being so small there is no chance that the block would wear to them and it has the effect of you loosing 50% of the braking area in my book.( like a slick tyre vs a treaded tyre in formula one)
I suppose it`s considered better in wet conditions maybe.

Well, I`ve ordered a couple of sets of different softer blocks to see what happens.

BTW the bike is an Evans of more than 20 years vintage and all the running gear is Shimano Exage which is very good. The front brake was 100% on the original Mavic rims.
Not sure why a lot of these wheels from China are grooved other than the wet thing, it can`t be to strengthen them because the grooves are not duplicated on the inside.

 

[Barnowl]

The deep black grove is there to indicate rim wear. No idea if the rest have any operational function or just left, as is, after production.

 

[Straylight]

I had similar machining groves in my rims, but managed to virtually eliminate them by running the braking surface past a bit of fine wet'n'dry sandpaper. I did this after comparing them to the Mavic rims on my Marin that are incredibly smooth, and give an even contact with the blocks. I think it helped the braking quite a lot, along with keeping the rims as true as possible, setting the brakes as tight as practical, and adjusting the brake spring tensions so that they contact the rim at the same time (not sure if your cantilevers have this setting).

 

[Old Timer]

Chain Reaction Cycles claim to stock soft pads for cantilevers Dave, I've seen a mention of Ritchey's red soft compound pads.
.

Tony

The blocks I ordered aren`t that good a fit. I`ve discovered what might be part of the problem.

The alien new front wheel is fairly narrow( around 1" wide at the braking area) whereas the Mavic rim that it replaced was a good 1 1/4". When I watch the action of these cantilevers brakes it looks to me that as the blocks get near the rim the angle of the cantilevers is quite high which(if I`m right) takes away the braking force. Have you come across that?Also by the time the blocks are touching the rim the angle of the blocks would prevent positive 100% contact. I could file down the blocks to meet more at the correct angle but that would make the angle of the cantilevers even greater and reduce braking even more.
I`m thinking that packing the blocks out closer to the rim would help but am not so keen having the blocks stuck out away from the mechanism(if you know what I mean) Another thought would be to fit wedge shaped spacers to bring the angle back but that would need to be done on the brake block side and also the retaining allen bolt side so that when tightened they wouldn`t move around.

any other ideas?

Thanks

Dave

 

[flecc]

No, I don't have any other idea Dave, these very narrow rims can really upset the geometry. Either one of those last two ideas should keep the leverage somewhere near optimum, whichever is easiest to implement. The lack of choice of cantilever components is quite a problem now that V and calipers have taken over the rim brake markets. Eventually it might be an idea to change to V brakes as Lloyd suggested.
.

 

[Old Timer]

I think I`m a bit inclined to maybe shape the brake block to fit the angle and then maybe pack the block out closer to the rim. That way I`ll be able to get a decent solid fix. If I cut angle spacers for inner and outer I don`t like the idea of everything relying on those angled spacers. I`ll have a go in the morning, I can only cock up a set of blocks at the end of the day. Even if the levers are not at the optimum angle I`m pretty sure if I get a better contact area they might work better.

 

[Old Timer]

Another thing I`ve just been considering, if the yoke than joins to the transverse cable is too high then the transverse cable would be longer and be pulling from a higher position where as if the tranverse cable is shortened it would force the yoke lower down and create more leverage when the brakes are applied. Yes??

 

[flecc]

Yes I agree, the more horizontal the transverse cabling, the better the grip might be, though I doubt it would be great difference within the usual range of cable angles. The geometry is always less effective than the other rim brake types and relies very much on pad softness.
.

 

[Old Timer]

Yes I agree, the more horizontal the transverse cabling, the better the grip might be, though I doubt it would be great difference within the usual range of cable angles. The geometry is always less effective than the other rim brake types and relies very much on pad softness.
.

Thanks Tony.

I`ll have a go today. BTW the front brake was 100% with the original smooth wider Mavic ali wheel (the back still is) After many years off of a bike and gaining a bit more confidence I now realise again just how the front brake can be the life saver if the worst happens( just like on a motorbike)

 

[Old Timer]

OK! carefully filed the existing brake blocks to match the wheel rim when touching(not easy) adjusted the transverse cable shorter to bring the main cable butterfly down and give a better angle. Then with the bike suspended ran the motor and used some medium grade emery paper to clean up the rim and take away the small ridge effect. Result! front brake around 50% improvement and that`s before it wears itself in better.

I did manage to find some old stock brake blocks to match my set up at a knock down price of 4 pairs for £6.50 so that will give me something to play around with in the future I reckon after 20 years my old blocks might also be suffering from dry out and hardening.

 

[Straylight]

Nice one OT!

Out here in EA, we may not need to brake very often, but when we do, we need them to work, I bet like me you've had the experience of meeting a tractor or lorry lurking around an unsighted bend on a narrow country lane.

I've spent a lot of time tinkering with my brakes/rims to get them to an optimal level, done some reading on the subject - particularly on Sheldon Brown's website, and he's a great exponent of the bias being mainly on the front brake. Having ridden mainly in London, I was a bit nervous about this at first, experience telling me that a rear skid is controllable, whereas losing traction/locking on the front courts inevitable disaster, particularly if you're turning at the time .

Over recent months though, I've been practising the technique(though for obvious reasons I've never got the rear wheel to lift off the ground!), and would now never go back to my old habits, you simply get far more retardation from the front brake. Unless it's wet, I now only use the rear to pulse in added braking force whilst smoothly slowing with the front. The extra weight of an ebike also means that braking/coming off the power has to be anticipated a lot earlier as well.

Happy riding .

 

[Alex728]

Nice one OT!

Out here in EA, we may not need to brake very often, but when we do, we need them to work, I bet like me you've had the experience of meeting a tractor or lorry lurking around an unsighted bend on a narrow country lane.
.

or a large badger deciding to run into your path