Stopping power of road bike brakes vs mtb brakes

Cubic

Hi, I went for a ride with my brother yesterday, me on my road bike with Shimano 105 brakes and my brother on his mtb with pretty cheap disc brakes. The difference between stopping power was huge - the disc brakes were much better.

Is this normal? I would have thought that with road bike being able to reach such high speeds they would have correspondingly powerful brakes. It's also possible that I need to change my brake pads as I've been using the same ones since I bought the bike four months ago. I'm not sure how you know when to change them though.

Any thoughts are greatly appreciated!

meagain

Even cheap Vs are much more effective stoppers than top end calipers. Simply more mechanically effecient - and the design of the levers and where they fit in the hand is also a better design.
Discs are of course better again.

redddraggon

TBH, I find traction to limit my breaking, rather than the power of the actual brake.

It's pretty easy to lock up my wheels, once the wheels have stopped turning how much more can a brake do?

sub55

redddraggon wrote:

TBH, I find traction to limit my breaking, rather than the power of the actual brake.

It's pretty easy to lock up my wheels, once the wheels have stopped turning how much more can a brake do?

ditto can lock up at 25 mph what more do you want

NWLondoner

I never slam on my brakes. Road wheels lock up very easily.

Best to graduate your braking and the front is usually more effective. Just not when going into a corner :shock:

markos1963

Have to agree, I have 105 brakes on my bike and can lock up anytime I want to. The problem is entirely due to a lack of grip, if you think about it, roadie tyres are designed to roll as freely as possible.

Rockhopper

markos1963 wrote:

Have to agree, I have 105 brakes on my bike and can lock up anytime I want to. The problem is entirely due to a lack of grip, if you think about it, roadie tyres are designed to roll as freely as possible.

You can lock up your front wheel can you?

whyamihere

The point with the more powerful brakes isn't that you can lock up the wheels. I can lock up both wheels on my mountain bike with V brakes, yet I still use hydraulic discs. They give far better control, meaning that you won't lock up. Any brake can lock a wheel, that's not a good way of finding out if a brake is any good. The amount of control you have is far more important.

whyamihere

Rockhopper wrote:

markos1963 wrote:

Have to agree, I have 105 brakes on my bike and can lock up anytime I want to. The problem is entirely due to a lack of grip, if you think about it, roadie tyres are designed to roll as freely as possible.

You can lock up your front wheel can you?

Easily. Just grab the lever hard.

STEFANOS4784

Yup, just pull the buggers, you might want to pad up before trying it though, think you probably need new brake blocks :arrow:

markos1963

Rockhopper wrote:

markos1963 wrote:

Have to agree, I have 105 brakes on my bike and can lock up anytime I want to. The problem is entirely due to a lack of grip, if you think about it, roadie tyres are designed to roll as freely as possible.

You can lock up your front wheel can you?

Actually I have, and the resulting stoppy had the rest of my club diving for cover.

beegee

Isn't the idea to not lock up the wheel because once it's locked up(a) it's not so effective at slowing (something to do with coefficient of sliding and static friction but it was a very long time ago) and (b) you've lost control. So I reckon that the trick is to be able to easliy (without much operator skill) take the brake to the vey limit without locking up and I think that for some reason mountain bike sets ups (brakes and tyres), giving more feeback, make braking to the very limit easier. But feel free to throw eggs if I'm wrong

alfablue

beegee, you may be right, but on a knobbly tyred mtb the lock-up will happen a lot easier, so the brakes may suggest more power, but it may not be all usable in a controlled manner on tarmac.

beegee

So has anyone actually tested bike brakes by strapping a sort of decelerometer to the bars ? Someone must've done a test ! Actually I suppose it would just be easier to ride two bikes at the same speed and then brake and see which one stops first. :oops:

roger_merriman

tires will go a long way to effecting braking, my old road bike has new brakes but it's still struggles on sharper braking as the tires are so thin. where as the older MTB with state of the ark braking can pull up even in horrible slippery road very nicely indeed.

juankerr

That's why we have disk brakes on cars, not rim brakes.

Even a top of the range V-brake is going to struggle against a cheap but properly set up hydraulic disk.

However you need to bare in mind that a MTB tyre is probably going to be around 35-50 psi and 2in wide so the contact patch under braking is going to be way bigger than a road tyre at 100psi. Also, an MTB riders weight is further back than on a bike with drop bars so your bro can pull on the front brake hard with less fear of going over the bars...

Beeblebrox

I can only echo what was said about road brakes aren't for locking wheels up. The contact area is so small the braking power of a locked up wheel is tiny compared to a MTB, plus you've lost nearly all control. use the brakes to graduate your speed and pedal intelligently, to prevent rapid acceleration and deceleration.

I can only guess that caliper brakes give better control without the risk of a sudden lock up or that they are just used as a type of tradition. But that's only a guess.

Nuggs

beegee wrote:

I reckon that the trick is to be able to easliy (without much operator skill) take the brake to the vey limit without locking up

Spot on - cadence braking is the most effective way of stopping.

Just watch the drivers on the WRC for a demonstration in how effective that technique is...

alfablue

if on tarmac, if you add up a few squirming knobbles on an mtb tyre and compare it to the contact patch on a road tyre there won't be a lot of difference, and the road tyre doesn't move about under braking. I don't think there is any reason to assume it will stop you better, on the contrary, mtb tyres are too easy to lock up on tarmac because of limited grip.

markos1963

juankerr wrote:

That's why we have disk brakes on cars, not rim brakes.

Even a top of the range V-brake is going to struggle against a cheap but properly set up hydraulic disk.

However you need to bare in mind that a MTB tyre is probably going to be around 35-50 psi and 2in wide so the contact patch under braking is going to be way bigger than a road tyre at 100psi. Also, an MTB riders weight is further back than on a bike with drop bars so your bro can pull on the front brake hard with less fear of going over the bars...

Actually the reason cars use disc brakes and not rim brake is due to heat build up. If you rim brake a car the heat generated is passed into the tyres with all the problems that entails. A rim brake with the same level of pressure at the contact point and the same level of brake friction will be many times more powerfull than a disc brake. This is due to the fact that the swept volume is greater. Check out a Buell motorbike for an example of how good rim braking can be.

roger_merriman

alfablue wrote:

if on tarmac, if you add up a few squirming knobbles on an mtb tyre and compare it to the contact patch on a road tyre there won't be a lot of difference, and the road tyre doesn't move about under braking. I don't think there is any reason to assume it will stop you better, on the contrary, mtb tyres are too easy to lock up on tarmac because of limited grip.

i think you'd struggle to find many if any MTB tires that had a smaller contact patch even at high pressures they are soft, and as plenty of MTB's tires are close on 3 times the width of your standard 23mm blade....