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I have recently been restoring a Btwin Triban-500 road bike, given to me from a friend who had let it sit around for a few years. I've rebuilt the bike sparing no expense, new inner tubes, cables, levers, chain, cassette and everything else has been thoroughly cleaned (with dish detergent, degreaser and re-greased).

It's been a fun project and I've currently got the brakes and rear derailleur connected. I've taken the bike for a spin around the block and I'm not happy with the braking power. I've got the brake cables tight and the pads are adjusted (i've done the same on my V-brake cheapo mountain bike and that stops quickly!). When I slam the brakes on the wheels lock up(front and back) but I take longer to stop than I'm perhaps used to. I mentioned my cheap mountain bike and those brakes are sharp (despite being cheap V-brakes). I've previously owned a hybrid with hydraulic discs and even half the lever was enough to violently throw me over the bars, I strive for brakes that powerful!

In comparison to my mountain bike, I'd say I take an extra half second to stop (I did a very scientific test past a street lamp). It worries me because the mountain bike is one of the cheapest rubbishest bikes from Halfords, surely the road should stop before it?

The mountain has 1.95 wide tyres and the road has 23mm tyres, will the reduced rubber be making a big impact (less friction) stopping the bike? or should I be able to get the rim brakes to perform just as well as the cantilevers?

Thanks

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    I don't understand. You say "I've currently got the brakes and rear derailleur connected", which strongly suggests that the front brakes aren't connected. That, right there, would explain your bad braking performance, since something like 70% of the braking power comes from the front wheel. But then you claim that you're locking up the front wheel while braking. Regardless of what brakes are connected, that's suspect, since a locked front wheel almost always throws you off the bike. So what's going on?
    – David Richerby
    Apr 4, 2019 at 12:42
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    Indeed, in my experience a locked front wheel almost always requires a change of underwear :)
    – Andy P
    Apr 4, 2019 at 12:43
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    @AndyP You shouldn't wear underwear with your cycling shorts! ;-) (Or maybe you should, since a change of underwear is much cheaper than a change of shorts.)
    – David Richerby
    Apr 4, 2019 at 12:49
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    Have you replaced the brake rubbers? Old one may become hard and lose stopping power. Have you degreased the rims? From sitting around they may have gathered greasy dust, especially while stored in a garage.
    – Carel
    Apr 4, 2019 at 13:38
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    Just to clarify: Are you really able to make the front wheel lock and skid on dry tarmac? Then the brakes are fine but the tires are rubbish.
    – Michael
    Apr 4, 2019 at 19:10

5 Answers 5

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You have already answered your own question really.

When I slam the brakes on the wheels lock up(front and back) but i take longer to stop than i'm perhaps used to.

If the brakes are strong enough to lock up the wheels they have plenty of power, but you have overcome the ability of the tyre to grip the road.

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    Do you think upgrading the tyres would be a good shout? I'm a little worried about the bikes ability to stop fast in traffic!
    – Axemasta
    Apr 4, 2019 at 12:33
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    I think upgrading the tyres to the very best you can afford is always a good shout on any bike. Tyres very much define how your bike performs. Tyres are responsible for grip (cornering and braking), rolling resistance, ride 'feel' and puncture resistance.
    – Andy P
    Apr 4, 2019 at 12:38
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    Some tires come with a thick wax coating and have full grip after the wax has worn away. Is suspect yours are one of these, because on a road bike you usually lift the rear wheel before locking front. Just do some riding to break them in.
    – ojs
    Apr 4, 2019 at 13:36
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    Noting of course that "best" is a function of many variables when it comes to tyres
    – Chris H
    Apr 4, 2019 at 18:55
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    @Axemasta, your question says you bought new tires but your comment says you're talking about old tires. Might want to clarify.
    – JPhi1618
    Apr 5, 2019 at 4:26
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The maximum braking force is achieved when the tire is just about to loose traction and start sliding on the road surface. Braking force decreases sharply as the tire begins to slide.

If you are locking both wheels, you are not getting maximum braking force, so try to modulate the force you are putting on the levers so that the wheels do not lock up. You should be able to apply more force on the front brake lever as the deceleration of your mass pushes the front tire against the road harder, making it more difficult to lock that wheel.

Also be aware that the 23mm road tires have a much smaller contact patch and therefore less grip. Higher tire pressure reduces the contact patch size, so you could try a lower tire pressure.

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  • Ok thankyou, I'm running 100psi at the moment, I'll try 80 tonight
    – Axemasta
    Apr 4, 2019 at 13:19
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    @Axemasta I get pinch flats on my 25mm tyres if I let the pressure get down to 80psi. Unless you're lighter than me (~73 kg), I wouldn't go below 90psi on 23mm tyres.
    – David Richerby
    Apr 4, 2019 at 13:37
  • @DavidRicherby risk of pinch flats depends on the surface as well as pressure and rider mass.
    – Argenti Apparatus
    Apr 4, 2019 at 14:49
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    @Michael while true to a first approximation, track bikes don't have brakes and roads are neither smooth nor clean enough in general for that statement to be particularly relevant
    – Chris H
    Apr 4, 2019 at 18:53
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    @Michael because grip isn't the only factor, and I never said there was the simple linear relationship over a wide range that you assume. But to some extent they do - on motorbikes
    – Chris H
    Apr 4, 2019 at 19:42
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A review I read says the brake calipers are own-brand and describes them as "basic" and "average". Possibly an upgrade there would help, but you'd have to decide if it's really worth spending that much money on a second-hand bike that only cost about £350 new.

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    Ok thats good to know. I got the bike for free and I'm restoring it as a personal project for a bit of fun. I've already spent money on many new components, I can pickup some second hand Tiagra brakes for pretty cheap so I think I'll do that!
    – Axemasta
    Apr 4, 2019 at 13:23
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    If OP is actually able to lock the front wheel then the current brakes are strong enough.
    – Michael
    Apr 4, 2019 at 19:07
  • Get second hand brakes... (seriously).
    – Peter - Reinstate Monica
    Apr 5, 2019 at 15:07
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    @Michael That's a huge "if". In a comment, the asker says "I'd assume that the front wheel is locking up too" and I think that's a bad assumption. Locking the front wheel of a bike while braking in a straight line basically sends you over the handlebars. The asker has (almost certainly incorrectly) inferred that they're locking the front wheel from the way the bike feels and not, for example, from seeing or hearing the front wheel skid along the ground.
    – David Richerby
    Apr 5, 2019 at 15:12
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    @DavidRicherby you are right, im going completely from feel in my example. The brake lever completely slammed in and the whole bike wobbling violently beneath me. Not very scientific!
    – Axemasta
    Apr 6, 2019 at 9:38
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You were definitely not locking up the front wheel or you'd be writing your question from the hospital because you lost all control, the wheels went out from under you and you fell.

You are also not the first one having this problem, the brakes seem poor (simply google "Btwin Triban-500 brakes").

Exchanging the brake pads is worth a try; if that does not work mount better brakes. The google search results include videos showing how to do that (what did we do before the internet?).

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  • Technically you don't lose all control, only steering and you get it back easily by letting the brake loose.
    – ojs
    Apr 5, 2019 at 15:58
  • @ojs Since all control on a bike is through steering you lose all control. Been there, done that. As an exercise, use the front brake on ice.
    – Peter - Reinstate Monica
    Apr 5, 2019 at 16:37
  • If your brake is set up so that you can't stop braking when front wheel locks, your bike is dangerous and you should stop riding it immediately. By the way, I live in Finland so riding on snow and ice isn't exactly unfamiliar to me.
    – ojs
    Apr 5, 2019 at 19:15
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TL;DR : your brakes are fine, a mountain bike is better at braking than a road bike.

A mountain bike have all the good reason in the world to be better at braking than a road bike : A road bike compromise everything to speed, weight, efficiency. a moutain bike is kind of the opposite, it focus on handling (braking is part of it).

The important things to consider in vehicle dynamic when braking :

  • the tire itself (compound, pressure, contact patch surface)
  • load transfer (the force applied to the tire)

Fore the tire itself, and considering it's just a bike and not a formula1 car,it's easy : the more vertical load and and the more surface you have on the road, the better. Unless you exceed the tire grip capacity.

When you brake, a lot of load transfer to the front wheel, thanks to inertia. In case of a bike this mass is you, the pilot. Being violently thrown over the over bar is not a good measure of braking power.

on a mountain bike :

  • you have a different position than on a road bike
  • you have suspensions !
  • you have a greater surface patch in contact with the road (more grip)

The suspension change how the load is transferred from back to front.

a little word about suspension :

  • The more mass you have on a tire, the better it "stick" to the road and the more braking force you can apply. (just draw force vector on a paper, it make sense)
  • So it could be just fine to have 100% of the mass to transfer to the front wheel and brake only with the front wheel, right ? wrong !
  • Because with 2 tire you have twice the surface patch on the road ! ha !
  • But you can't help mass transferring to the front wheel (inertia). Well... kind of. In fact, you can, and it's the main role of suspension. The front suspension (it super weird and not intuitive) transfer the mass back to the rear wheel. And with a better distribution of mass on all wheel you can make the best of all the surface contact patch you have between the vehicle and the road.

I'll stop here with the explanation because you can spend a lifetime (and many thesis) on this subject.

Do not lock up, your brake are fine, your front/rear braking power distribution is different on MTB/Road, do not throw yourself over the bars on purpose, MTB are better at braking than road bike.

edit : it's early in the morning, not enough coffee. i'll probably re-edit this post to make it more readable (if needed).

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    Please do so. This is completely incomprehensible.
    – ojs
    Apr 5, 2019 at 9:02
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    Yes, there's some good points in here, but lost amongst the clutter
    – Andy P
    Apr 5, 2019 at 10:04
  • i edited a bit, i'll continue editing later. i'm at work :)
    – ker2x
    Apr 5, 2019 at 10:32
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    "A road bike compromise everything to speed, weight, efficiency" Sorry but that's nonsense. If a bike is designed to go quickly, then good brakes are absolutely essential for safety. And most new-model road bikes these days have disc brakes, even though they are heavier than rim brakes.
    – David Richerby
    Apr 5, 2019 at 14:44
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    ...which doesn't really prove anything, since braking on road bike is limited by weight distribution, not brake power.
    – ojs
    Apr 5, 2019 at 14:57

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