Reason for massive difference in brake performance ?

yertez
yertez Posts: 80
edited December 2017 in Workshop
[A] The Ultegra brakes on my Canyon Ultimate with Mavic Ksyrium elite wheels are excellent.

My B'Twin Triban 500 (winter roadie) with Decathlon brakes and Mavic Aksium wheels are really not much use at all.

Any ideas what causes such a difference before I start randomly replacing bits ?

(same Ultegra brake pads on both)
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Comments

  • trivial_poursuivant
    trivial_poursuivant Posts: 1,136
    Some third party brakes are shocking. Some are also much better. The design, strength of the spring, cable pull ratio all effect a brakes ability. Thing is Shimano Ultegra are some of the best (pound for pound) out there. You could get DA at a much inflated price for not much more efficiency. I used to have a set of Vision aero brake calipers on my TT bike. They were terrible on both Clincher and Tubular rims. But then on a TT bike your not likely to be zooming down a 20% gradient at 60mphso it’s a compromise.

    One thing I would say is, are they set up correctly? Do they make a solid contact with the braking surface with a decent lead on the pad? (Slight toe in angle on the pad so it’s not hitting the rim flat)
  • svetty
    svetty Posts: 1,904
    Cheapish upgrade would be to get 105 5800 brakes for the winter bike - assuming that the drop is adequate?
    FFS! Harden up and grow a pair :D
  • yertez
    yertez Posts: 80
    Would it be the callipers or the levers or a combo of both do you reckon ?
  • milemuncher1
    milemuncher1 Posts: 1,472
    edited December 2017
    yertez wrote:
    Would it be the callipers or the levers or a combo of both do you reckon ?

    A combination of both. Over the years, I’ve tried all sorts of brake set ups on all sorts of bikes. Like you, I have the Ultegra 6800 set up on my Ultra 720 AF, with Mavic Cosmic Elite rims, and a Triban 520, with Sora brakes, on Mavic Aksium rims. The difference is night and day. I have improved the performance of the standard Sora brakes, by changing pad compounds. I’m using Clarks ‘elite performance’ pads at the moment, and they have improved things a lot. I was thinking of swapping the brakes for 5800s, but if I was doing that, I wouldn’t get the full improved effect, without the Brifters. I might as well do the whole groupset, as the Brifters on the 5800 are for an 11 speed set up anyway.
  • Alex99
    Alex99 Posts: 1,407
    It would be relatively simple for someone with the right kit to do some proper testing. If one had access to a mechanical engineering lab, some measurements of lever force and caliper force with different combinations of kit would be interesting. I suspect that caliper stiffness is a major factor, but also crummy levers will flex.
  • timothyw
    timothyw Posts: 2,482
    Is part of it the conditions? I mean, good conditions for riding (in which you're likely to be riding the good bike) tend to be good conditions for braking too....

    There are lots of reasons though. For one, the 6800 brake calipers are considerably more stiff than previous models (and no doubt the cheap decathlon ones) which gives better braking. They're actually a fair bit heavier than the equivalent brake models from a decade ago, but they brake a lot better.

    Secondly, the feel of the levers is better in the new generation of Shimano groups - I noticed that the brakes felt better on my bike when I upgraded the gears from 4600 tiagra to 5800 105, despite the fact I didn't upgrade the brakes at the time.

    Then there's the question of the cable run - compressionless outers will improve the transfer of force to the calipers, although historically it has been argued that they make it harder to modulate the braking force. Either way, if the cable run is gunked up or the cables rusty then they'll increase friction to the system and so make it harder for you to pull the brakes. Equally, the calipers themselves might need servicing if they've become gunked up and stiff.

    I had an old Benotto which wasn't in the best shape, when I replaced the original calipers with some Tektros I had on the shelf and put on fresh cables with compressionless outers it was ridiculous the difference it made. I could stop....
  • lesfirth
    lesfirth Posts: 1,382
    Alex99 wrote:
    It would be relatively simple for someone with the right kit to do some proper testing. If one had access to a mechanical engineering lab, some measurements of lever force and caliper force with different combinations of kit would be interesting. I suspect that caliper stiffness is a major factor, but also crummy levers will flex.

    Flexing in the caliper or lever makes no difference to the force applied to the brake pad. You need to understand why a rubber crow bar is as good as a steel crow bar to get your head around why. :)
  • rick_chasey
    rick_chasey Posts: 72,734
    lesfirth wrote:
    Alex99 wrote:
    It would be relatively simple for someone with the right kit to do some proper testing. If one had access to a mechanical engineering lab, some measurements of lever force and caliper force with different combinations of kit would be interesting. I suspect that caliper stiffness is a major factor, but also crummy levers will flex.

    Flexing in the caliper or lever makes no difference to the force applied to the brake pad.

    You might need to explain this to me, since it feels counter-intuitive. Force used to flex the caliper is therefore not being applied to the rim, no?
    _
  • fenix
    fenix Posts: 5,437
    I'd give the rim and the blocks a good clean before spending money. Its very cruddy out there. Much worse than your summer bike will have had.

    If its still rubbish then yeah I'd look to swap things.
  • pilot_pete
    pilot_pete Posts: 2,120
    Fenix wrote:
    I'd give the rim and the blocks a good clean before spending money. Its very cruddy out there. Much worse than your summer bike will have had.

    If its still rubbish then yeah I'd look to swap things.

    Yes, good call. Roughen up the brake pad with some wet and dry/ sandpaper, bed them back in and assess again. Assuming everything is working as designed (clean and mechanically sound) I would have thought that upgrading the pads would be the cheapest upgrade to try first.

    However, you will probably find that you are comparing the performance of a Nissan GTR to a Smart car - one has significantly better performance than the other due to a whole multitude of reasons....and comes at a price tag that reflects that.

    Your Triban was built to a price point so many compromises have had to be made regarding the quality of components that have been fitted to it. Doesn't make it bad, merely that it is unlikely to have the same performance as something more expensive (although that generalisation doesn't always apply!)

    I would go for an upgrade to something like 105, which has most of the performance for a very competitive price.

    PP
  • Alex99
    Alex99 Posts: 1,407
    lesfirth wrote:
    Alex99 wrote:
    It would be relatively simple for someone with the right kit to do some proper testing. If one had access to a mechanical engineering lab, some measurements of lever force and caliper force with different combinations of kit would be interesting. I suspect that caliper stiffness is a major factor, but also crummy levers will flex.

    Flexing in the caliper or lever makes no difference to the force applied to the brake pad. You need to understand why a rubber crow bar is as good as a steel crow bar to get your head around why. :)

    Yeah, I get it. The thing may flex, but force is force.

    Sounds like you understand such things... do you suggest that stiffness isn't important, or are there other things at play?
  • timothyw
    timothyw Posts: 2,482
    Alex99 wrote:
    lesfirth wrote:
    Alex99 wrote:
    It would be relatively simple for someone with the right kit to do some proper testing. If one had access to a mechanical engineering lab, some measurements of lever force and caliper force with different combinations of kit would be interesting. I suspect that caliper stiffness is a major factor, but also crummy levers will flex.

    Flexing in the caliper or lever makes no difference to the force applied to the brake pad. You need to understand why a rubber crow bar is as good as a steel crow bar to get your head around why. :)

    Yeah, I get it. The thing may flex, but force is force.

    Sounds like you understand such things... do you suggest that stiffness isn't important, or are there other things at play?
    It obviously does make a difference, whether it is stiffness or something else, otherwise the current Shimano brakes wouldn't be noticeably better than their lighter, skinnier predecessors, and crowbars made of rubber would actually be available, rather than just part of a thought experiment.
  • cld531c
    cld531c Posts: 517
    I changed the pads on my Triban, much improved but still pretty poor braking.
    Its probably a combination of cheap cables, levers, calipers and blocks. The whole point of that bike for me was its cheapness so its getting nothing else, I just wont be riding down Wynrose pass on it again :-)
  • lesfirth
    lesfirth Posts: 1,382
    TimothyW wrote:
    Alex99 wrote:
    lesfirth wrote:
    Alex99 wrote:
    It would be relatively simple for someone with the right kit to do some proper testing. If one had access to a mechanical engineering lab, some measurements of lever force and caliper force with different combinations of kit would be interesting. I suspect that caliper stiffness is a major factor, but also crummy levers will flex.

    Flexing in the caliper or lever makes no difference to the force applied to the brake pad. You need to understand why a rubber crow bar is as good as a steel crow bar to get your head around why. :)

    Yeah, I get it. The thing may flex, but force is force.

    Sounds like you understand such things... do you suggest that stiffness isn't important, or are there other things at play?
    It obviously does make a difference, whether it is stiffness or something else, otherwise the current Shimano brakes wouldn't be noticeably better than their lighter, skinnier predecessors, and crowbars made of rubber would actually be available, rather than just part of a thought experiment.

    This subject has been done to death over years on this forum. I am not going to start again.

    Tim, you must have been off ill when they had general science at school. I suggest that you do a bit of googling to learn what you obviously missed.
  • Alex99
    Alex99 Posts: 1,407
    lesfirth wrote:
    TimothyW wrote:
    Alex99 wrote:
    lesfirth wrote:
    Alex99 wrote:
    It would be relatively simple for someone with the right kit to do some proper testing. If one had access to a mechanical engineering lab, some measurements of lever force and caliper force with different combinations of kit would be interesting. I suspect that caliper stiffness is a major factor, but also crummy levers will flex.

    Flexing in the caliper or lever makes no difference to the force applied to the brake pad. You need to understand why a rubber crow bar is as good as a steel crow bar to get your head around why. :)

    Yeah, I get it. The thing may flex, but force is force.

    Sounds like you understand such things... do you suggest that stiffness isn't important, or are there other things at play?
    It obviously does make a difference, whether it is stiffness or something else, otherwise the current Shimano brakes wouldn't be noticeably better than their lighter, skinnier predecessors, and crowbars made of rubber would actually be available, rather than just part of a thought experiment.

    This subject has been done to death over years on this forum. I am not going to start again.

    Tim, you must have been off ill when they had general science at school. I suggest that you do a bit of googling to learn what you obviously missed.

    What a lovely reply.
  • navrig2
    navrig2 Posts: 1,844
    The factors which will affect the effectiveness of rims brakes will be:

    Force applied at the lever (the harder you pull the more force will be available at the rims)
    Efficient transfer of that force (cable route and friction between cable and outer)
    Type of leverage used by the calipers to apply that force
    Stiffness of calipers - if the caliper flexes then some of the force is not being applied.
    Brake block material
    Brake block condition
    Quantity of water on rim
    Quantity of water being applied to rim (is it raining, are the puddles deep, is there a lot of spray)
    Quantity of crud (scientific term) on rim

    These are not in order of impact because the level of impact will depend on the particular brakes.

    I have 6800 calipers and a year ago replaced 5700 calipers with 5800 calipers when the winter bike was re-cabled.

    By far the 6800 are best. I believe this is a combination of better caliper design in relation to leverage applying force, more efficient transfer of force due to better cable routing and coated cables reducing friction with the outers.

    The 5800 are better than the 5700 were and I think this is down to better leverage.

    I suspect cheaper calipers have a different leverage arrangement and flex more.
  • shortfall
    shortfall Posts: 3,288
    edited December 2017
    lesfirth wrote:
    TimothyW wrote:
    Alex99 wrote:
    lesfirth wrote:
    Alex99 wrote:
    It would be relatively simple for someone with the right kit to do some proper testing. If one had access to a mechanical engineering lab, some measurements of lever force and caliper force with different combinations of kit would be interesting. I suspect that caliper stiffness is a major factor, but also crummy levers will flex.

    Flexing in the caliper or lever makes no difference to the force applied to the brake pad. You need to understand why a rubber crow bar is as good as a steel crow bar to get your head around why. :)

    Yeah, I get it. The thing may flex, but force is force.

    Sounds like you understand such things... do you suggest that stiffness isn't important, or are there other things at play?
    It obviously does make a difference, whether it is stiffness or something else, otherwise the current Shimano brakes wouldn't be noticeably better than their lighter, skinnier predecessors, and crowbars made of rubber would actually be available, rather than just part of a thought experiment.



    This subject has been done to death over years on this forum. I am not going to start again.

    Tim, you must have been off ill when they had general science at school. I suggest that you do a bit of googling to learn what you obviously missed.

    Oh go on cos I don't get it (I might be just thick admittedly) but if rubber crowbars are just as effective as metal ones, why are they all made out of metal?
  • yertez
    yertez Posts: 80
    So it's looking like a combination of all the brake parts.

    I might whip one of the Ultegra callipers off the Canyon and try it on the Triban rear wheel.

    Then swap rear wheels too.
    Out of curiosity.
  • lesfirth
    lesfirth Posts: 1,382
    Oh go on cos I don't get it (I might be just thick admittedly) but if rubber crowbars are just as effective as metal ones, why are they all made out of metal?[/quote][/quote]

    Others may be able to but I would need more than a few paragraphs to explain.

    While back on the subject,Shimano 6800 calipers have a unique pivot and roller system that( as I see it) gives it some variable leverage.They are much better than others I have used.
  • timothyw
    timothyw Posts: 2,482
    lesfirth wrote:
    Oh go on cos I don't get it (I might be just thick admittedly) but if rubber crowbars are just as effective as metal ones, why are they all made out of metal?

    Others may be able to but I would need more than a few paragraphs to explain.

    While back on the subject,Shimano 6800 calipers have a unique pivot and roller system that( as I see it) gives it some variable leverage.They are much better than others I have used.
    Funny, when I said they were better you seemed to think that I must have missed a few science lessons in school...

    :lol::lol::lol:
  • yertez
    yertez Posts: 80
    Right, just been in the garage swapping over calipers.
    And with the calipers off and side by side, activating them by hand immediately shows a huge difference in the force required to compress the spring. 6800 being much easier to compress with more moving parts and a positive (almost clicky) action when compressed.

    That said, the proof is in the pudding as they say. So with my B'Twin kitted with an Ultegra 6800 rear caliper the braking was ....... <drum roll > .... still pretty average.

    Hmmm... so I put the B'Twin caliper back on and replaced the pads with Ultegra ones slightly roughened with sand paper.
    A slight improvement, but still spongebob.
    Difficult even to lock the wheel which is v easy on the Canyon.

    So in conclusion, it's not the caliper, and buying some 105/6800 calipers won't solve the issue.

    You'd expect the cables to be much of a muchness, the outer sheath is pretty standard across bikes.

    So most probably the levers then... and that's a bit more of a faff to switch over, but worth it before laying out £50+ per side.
  • navrig2
    navrig2 Posts: 1,844
    I understand the standard Ultegra 6800 fit includes low friction cables. The come coated with a black plastic material.
  • milemuncher1
    milemuncher1 Posts: 1,472
    yertez wrote:
    So it's looking like a combination of all the brake parts.

    I might whip one of the Ultegra callipers off the Canyon and try it on the Triban rear wheel.

    Then swap rear wheels too.
    Out of curiosity.

    Braking systems are called that for a reason. All the individual components combine in a way they are carefully designed to. Much like dissecting a kitten, if you isolate the individual components, you don’t get the full effect, the designers intended. The wheel’s braking surface is important as well.
  • cld531c
    cld531c Posts: 517
    Milemuncher1 wrote:
    yertez wrote:
    So it's looking like a combination of all the brake parts.

    I might whip one of the Ultegra callipers off the Canyon and try it on the Triban rear wheel.

    Then swap rear wheels too.
    Out of curiosity.

    Braking systems are called that for a reason. All the individual components combine in a way they are carefully designed to. Much like dissecting a kitten, if you isolate the individual components, you don’t get the full effect, the designers intended. The wheel’s braking surface is important as well.

    Surely you are not advocating changing the cables, levers, calipers and wheels?
  • rolf_f
    rolf_f Posts: 16,015
    Trivial poursuivant wrote:
    Some third party brakes are shocking. Some are also much better. The design, strength of the spring, cable pull ratio all effect a brakes ability.

    Unless over-strong, all the springs do is keep the pads away from the rims so I don't see how they can have much impact on braking effectiveness. And really, what difference does cable pull ratio make unless it gets extreme? How big a mechanical difference actually is there out there?
    Faster than a tent.......
  • Alex99
    Alex99 Posts: 1,407
    Milemuncher1 wrote:
    yertez wrote:
    So it's looking like a combination of all the brake parts.

    I might whip one of the Ultegra callipers off the Canyon and try it on the Triban rear wheel.

    Then swap rear wheels too.
    Out of curiosity.

    Braking systems are called that for a reason. All the individual components combine in a way they are carefully designed to. Much like dissecting a kitten, if you isolate the individual components, you don’t get the full effect, the designers intended. The wheel’s braking surface is important as well.

    Sorry to point this out the gaping holes in your analogy, but kittens weren't designed. Also, irrespective of the components, all kittens are cute and cuteness is clearly the desirable "effect".
  • Alex99
    Alex99 Posts: 1,407
    cld531c wrote:
    Milemuncher1 wrote:
    yertez wrote:
    So it's looking like a combination of all the brake parts.

    I might whip one of the Ultegra callipers off the Canyon and try it on the Triban rear wheel.

    Then swap rear wheels too.
    Out of curiosity.

    Braking systems are called that for a reason. All the individual components combine in a way they are carefully designed to. Much like dissecting a kitten, if you isolate the individual components, you don’t get the full effect, the designers intended. The wheel’s braking surface is important as well.

    Surely you are not advocating changing the cables, levers, calipers and wheels?

    Hmm, some kind of analysis involving roll downs, various components, and constant brake lever force needs to be done.
  • cld531c
    cld531c Posts: 517
    Or just make do with what you have!
  • cld531c
    cld531c Posts: 517
    Alex99 wrote:
    Milemuncher1 wrote:
    yertez wrote:
    So it's looking like a combination of all the brake parts.

    I might whip one of the Ultegra callipers off the Canyon and try it on the Triban rear wheel.

    Then swap rear wheels too.
    Out of curiosity.

    Braking systems are called that for a reason. All the individual components combine in a way they are carefully designed to. Much like dissecting a kitten, if you isolate the individual components, you don’t get the full effect, the designers intended. The wheel’s braking surface is important as well.

    Sorry to point this out the gaping holes in your analogy, but kittens weren't designed. Also, irrespective of the components, all kittens are cute and cuteness is clearly the desirable "effect".

    Now I know why MM gets my heckles up, it isn't the self righteous contradictory BS after all - HE IS A KITTEN MURDERER.
    And you are quite correct, all kittens are cute.
  • yertez
    yertez Posts: 80
    Di2 brakes ?
    :)

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