Reading an article extolling disk brakes on bikes I was struck by a claim that rim brakes wear aluminium wheel rims badly. Do they? That is something I confess never to have thought about.
Brake rim wear
- Thread starter tgame
- Start date
It does happen Tony, I have had to replace a front rim at approx 5000 miles, a Weinmann at that so certainly reasonable quality. I do know however that cheap'n'nasty brake pads had been used prior to my ownership of that bike which I feel had contributed considerably to the wear. Another bike of mine was showing front rim wear at less than 1000 miles, this however was a cheap rim with cheap brakes.
On a happier note the front rim on my Ezee Torq is showing no signs of wear after a couple of thousand miles, the tool marks still being visible on the side faces. This bike has had quality pads from new, Tektro originally and Shimano now.
Those 99p brake pads at Asda may seem a bargain compared to £6 or £7 for the real thing but they do carry a hidden cost!
On a happier note the front rim on my Ezee Torq is showing no signs of wear after a couple of thousand miles, the tool marks still being visible on the side faces. This bike has had quality pads from new, Tektro originally and Shimano now.
Those 99p brake pads at Asda may seem a bargain compared to £6 or £7 for the real thing but they do carry a hidden cost!
There's quite severe wear on the 20" rims of my Q bike now at around 2000 miles plus, smaller wheels and a steep hill area being the cause of that. I use good quality long pads.
It does need watching in the late stages since at some point the tyre blows out the rim walls when braking, collapsing the wheel, potentially a nasty accident if it's the front wheel.
Many rims have "telltales", a groove running around the centre of the rim wall. When the groove can no longer be seen, it's time for a new rim.
Years ago when bikes had steel rims, wear was never a problem, but there was no braking strength in the wet, hence the adoption of alloy which is ok for braking wet or dry.
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It does need watching in the late stages since at some point the tyre blows out the rim walls when braking, collapsing the wheel, potentially a nasty accident if it's the front wheel.
Many rims have "telltales", a groove running around the centre of the rim wall. When the groove can no longer be seen, it's time for a new rim.
Years ago when bikes had steel rims, wear was never a problem, but there was no braking strength in the wet, hence the adoption of alloy which is ok for braking wet or dry.
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Well well. I've always said that I could see no justification for disk brakes on bicycles! Now I know better. What pads ought I to buy for my Agattu when they become needed (not for ages probably considering my ambling style of riding)?
The Avid 20R set are good quality at a very moderate price. Otherwise, a lower price set of Shimano pads such as the Deore or M system pads are good.
Those are in the £5 to £9 regions, but you can go mad at up to £40 plus if you like, though I doubt theres any benefit apart from a possible feel good factor.
I still think of disc brakes as a gimmick, frail, easily damaged, overheating and damaging hubs at times, and never seen in serious bike racing.
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Those are in the £5 to £9 regions, but you can go mad at up to £40 plus if you like, though I doubt theres any benefit apart from a possible feel good factor.
I still think of disc brakes as a gimmick, frail, easily damaged, overheating and damaging hubs at times, and never seen in serious bike racing.
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With large diameter wheels, a sedate riding style, not too many muddy trails or steep decents there's little to worry about Tony. And if a rim does eventually need replacement it is a simple enough job for a competent bicycle mechanic.
M
mk1
Guest
It would be disc brakes every time for me, I don't recognise the problems stated by flecc. The advantages are they work better, don't damage your rims, they are cleaner(you dont get the horrible black residue from the rims all over your wheels and tyres).
I have never damaged one on road or off. They maybe slightly heavier which could explain why they are not used on racing bikes, or it could be that roadies are luddites that don't accept change easily
Discs are great for utility bikes in my opinion
I have never damaged one on road or off. They maybe slightly heavier which could explain why they are not used on racing bikes, or it could be that roadies are luddites that don't accept change easily
Discs are great for utility bikes in my opinion
The overheating and damage are in long high speed descents, which is why they aren't used in serious road racing, nothing to do with luddism, since they are type approved for racing
They are vulnerable to damage due to the thin nature of cycle discs, and many are changed when they buckle, either from physical damage, or more commonly from overheating and warping. That's why all the best makes have replacement discs available.
Discs don't work better in braking force terms, since any disc brake's effectiveness is primarily determined by it's diameter, and a rim brake is the biggest disc of all.
They are certainly cleaner and avoid rim wear, and with moderate road use are fine. I wouldn't want them in my excessively hilly area with many long descents though.
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They are vulnerable to damage due to the thin nature of cycle discs, and many are changed when they buckle, either from physical damage, or more commonly from overheating and warping. That's why all the best makes have replacement discs available.
Discs don't work better in braking force terms, since any disc brake's effectiveness is primarily determined by it's diameter, and a rim brake is the biggest disc of all.
They are certainly cleaner and avoid rim wear, and with moderate road use are fine. I wouldn't want them in my excessively hilly area with many long descents though.
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M
mk1
Guest
Disc brakes are used in Downhill mountain bike racing and Cross Country racing, which can get quite serious sometimes.
I can only go by my my own experience and that is that they have better stopping performance than any rim brakes I have tried. If they do get damaged then they are much easier to replace than a rim would be.
I was only joking about the roadies.
Martin
It was of course road racing I was referring to. Discs often make sense on mountain bike downhills I know, loose stones can dangerously lock into a rim brake and mud can clog them up severely.
I've helped local riders at times when out walking in the countryside and I've found them with wheels seized right up with hard sticky mud clogging the rim brakes, wheel and fork heads into a solid lump.
They had stopped them though.
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I've helped local riders at times when out walking in the countryside and I've found them with wheels seized right up with hard sticky mud clogging the rim brakes, wheel and fork heads into a solid lump.
They had stopped them though.
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In my view discs are an overkill on most bikes, rim brakes are simple, light and effective, the Deore XT on my Torq will stand it on its front wheel and I have no desire for anything with more power than that .
Discs were developed for serious mountain bikes, and it's where the mud is thickest that they have a real advantage. They are unsuitable for use with lightweight wheels who's spokes are incapable of transmitting strong braking forces which along with the weight penalty is why they're never seen on racing bikes.
It could of course be argued that they are well suited to hub motor wheels which are of necessarily strong construction. but it could equally be argued that such wheels are heavy enough already.
The better rim brakes have a parallel action that mimics a disc caliper, but operating on a very large disc, but also maintain a finite clearance between pad and rim eliminating all drag when the brake is released.
Its horses for courses but I see discs as being for mountain bikes, rims for road, and totally enclosed drums for utility use, as used on the ultimate utility bike, the Royal Mail Pashley.
.Discs were developed for serious mountain bikes, and it's where the mud is thickest that they have a real advantage. They are unsuitable for use with lightweight wheels who's spokes are incapable of transmitting strong braking forces which along with the weight penalty is why they're never seen on racing bikes.
It could of course be argued that they are well suited to hub motor wheels which are of necessarily strong construction. but it could equally be argued that such wheels are heavy enough already.
The better rim brakes have a parallel action that mimics a disc caliper, but operating on a very large disc, but also maintain a finite clearance between pad and rim eliminating all drag when the brake is released.
Its horses for courses but I see discs as being for mountain bikes, rims for road, and totally enclosed drums for utility use, as used on the ultimate utility bike, the Royal Mail Pashley.
The true drum brakes like car ones aren't bad, though not particularly strong in braking force due to their small diameter. They do wear though, and the linings are vulnerable to grease seeping in. They seem to be disappearing, and SRAM are no longer making the hub gear versions with them.
The other sorts are roller brakes with rollers that ride on ramps when activated and so tend to lock the drum rotation. They do run greased, but tend to a be rather weak acting, the braking effect coming in slowly, not ideal for emergency stops. For that reason they are mostly found on utility bikes. The Shimano one for example is rated for 100 kilos weight, easily exceeded on an e-bike with a heavy rider or loaded with shopping, hence the weak action as it spends most of it's life near to design limits.
The Coaster brake is a variation of those, operating by back pedalling. It's not popular in the UK, but often found in the low countries.
P.S. Ian was in first this time, and between us I think we've covered nearly the whole field of bike braking!
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The other sorts are roller brakes with rollers that ride on ramps when activated and so tend to lock the drum rotation. They do run greased, but tend to a be rather weak acting, the braking effect coming in slowly, not ideal for emergency stops. For that reason they are mostly found on utility bikes. The Shimano one for example is rated for 100 kilos weight, easily exceeded on an e-bike with a heavy rider or loaded with shopping, hence the weak action as it spends most of it's life near to design limits.
The Coaster brake is a variation of those, operating by back pedalling. It's not popular in the UK, but often found in the low countries.
P.S. Ian was in first this time, and between us I think we've covered nearly the whole field of bike braking!
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Last edited:
M
mk1
Guest
I quite like drum brakes for their low maintenance advantages they are a bit heavy though which is not really too much of a problem on utility type bikes.
I can't stand coaster brakes.
Martin
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