Road Bikes - Why no hydraulics?

[Dan B]

What about overheating of the discs causing them to warp

Fair point

 

[topcat1]

http://www.factor001.com/gallery

was on the gadget show a couple of months back

and there is DI2 electronic gear changing as used by team sky ( and me)

 

[Cubist]

Can I just butt in here? I can't be bothered to quote all of the blinding misconceptions that some people have typed.

My Boardman Hybrid Pro is a road bike. It has flat bars, but otherwise is a road bike. It has 700c wheels shod with 25mm tyres. It has a carbon fork and a 50-36 Truvativ Elita Crankset, so apart from the flat bars is essentially a roadbike.

As we found out on Sunday, it isn't outgunned by the dropbar bikes, and in fact kept up with them admirably.

It has hydraulic disc brakes. I don't have figures to hand, but the Avid Elixir R system on mine cannot possibly weigh much more than a standard set of rim brakes. The added weight of the rotor may even be partially cancelled out by the lighter rims (no braking surface required), so my argument is that the weight penalty issue is negligible, if not nonsense. My whole bike weighs less than 9kg.

Next comes performance. Nothing comes close. The feel and modulation available from the disc brakes is a joy to work with. There is NO maintenance penalty. I clean them once a week. They don't need adjusting, and mine are on the same set of pads since I bought it in June 2009, so "They are a faff to adjust" is, simply, bollocks!

Wet conditions, great. They work. Very well. Rim brakes don't, live with it.

Torsion on a road fork? Bollocks, sorry, mine has a carbon fork.

Only snobbery is keeping disc brakes off road bikes. I love mine, and if you flat-earthers want to spout garbage about weight and torsion carry on, but you'd be wrong!

 

[Cubist]

What about overheating of the discs causing them to warp, I think I read about that somewhere as a downside to discs on long descents with luggage.

Shimano have added cooling fins to the pads and a forced air cooling system to XTR brakes.

 

[Cubist]

I can't help but think that disc brakes on a road bike would prove to be a persistent nuisance, and so far, I've had no issues with calipers in wet or dry conditions.Unlike the mtb I had which had disc breaks and was a regular nuisance, especially one time when the wheel was knocked slightly out of true, it stopped all riding.

So how did a wheel knocked out of true affect disc braking? If anything the joy of discs on a MTB is that you can still ride with a buckled wheel 'cos the brakes will still work. If you found them a nuisance it'll be because you failed to learn how to look after them I suspect!

 

[Cyclopathic]

Harrumph. I really must introduce you to the "braking" of my Galaxy in the wet.

The fact is, a well set up rim brake is every bit as good as disk brakes - in the dry. Hydraulic disk brakes do give you better modulation though. Which is nice, but not really essential. Where disk brakes shine is in the wet. Even the best rim brakes need one revolution of the wheel in order to remove the water off the rim before biting. That's two metres of travel which could make a big difference in an emergency. Disk brakes work instantly. I know which I'd rather have when it's raining.

As for the front forks not being up to coping with the additional torsional loads imposed by disk brakes? I'm skeptical. Forks have to cope with very high loads on occasion (particularly when you're crashing through that pothole you couldn't avoid!). If they can't cope with disk brakes, they're not fit for purpose.

I find a liberal coating of wd40 on the rims helps to repel the water. However...

 

[Piemaster]

Wet conditions, great. They work. Very well. Rim brakes don't, live with it.

Torsion on a road fork? Bollocks, sorry, mine has a carbon fork.

Only snobbery is keeping disc brakes off road bikes. I love mine, and if you flat-earthers want to spout garbage about weight and torsion carry on, but you'd be wrong!

Time for my back to back (almost) comparison.
My on-one pompino, with drop bars.

Last week, carbon fork and froggslegs cantilever rim brakes, with swisstop pads - just to prove this was actually the best I could get them to work. It stopped, but never had that much confidence in it, especially at 40mph down an Aberdeenshire hill with a main road crossing the bottom of it. A "stop you <expletive> <expletive>" on one wet descent decided it for me.

This week. New pompetamine fork (to get disc brake caliper mount) with shimano M495 brakes, not the more favoured avid BB7. After a test ride in the dry I was sceptical and wondered had it been worth the expense and bother. Until I went out in a downpour. It was more than worth it, and as it was the 2nd time I'd been out on it since the conversion it should improve as the pads bed in.

The other bike (giant escape) has hydraulic discs (avid juicy 3) and I've never had to touch them in 4 years. If there was hydraulic drop levers/discs available I'd have them like a shot.

 

[Zoiders]

Torsion on a road fork? Bollocks, sorry, mine has a carbon fork.

Only snobbery is keeping disc brakes off road bikes. I love mine, and if you flat-earthers want to spout garbage about weight and torsion carry on, but you'd be wrong!

You might not break a fork with discs but you might manage to tear the hub out of the drop out, it can happen, thats why some MTB forks use the thru-lo bolted arangement.

I think when people say "road" they think team replica bikes which on the whole are never really the best choice for most riders.

 

[Cubist]

What, a bit like when people say "car" they mean Formula One racer?

 

[the_mikey]

So how did a wheel knocked out of true affect disc braking? If anything the joy of discs on a MTB is that you can still ride with a buckled wheel 'cos the brakes will still work. If you found them a nuisance it'll be because you failed to learn how to look after them I suspect!

Thanks! The wheel was knocked out of true by riding it, crashing it, among other things I suspect. Road bike wheels get knocked out of true a lot too, but they're really quickly replaced, so I'm not going to groan about them.

 

[Cubist]

Yes, but a MTB wheel out of true will not affect how the brakes work, whereas a rimbrake wheel will. Unless of course you bend the axle or rip the hub, in which case braking becomes academic!

What aspect of a MTB wheel makes it more difficult to replace than a road wheel?

 

[snailracer]

What, a bit like when people say "car" they mean Formula One racer?

Would you prefer it if sporty "road" bikes were called "racing" bikes, as they used to be?

 

[Cubist]

Would you prefer it if sporty "road" bikes were called "racing" bikes, as they used to be?

No, I was picking up on the poster's mangling of the definition to suit his (flawed) argument that road bike forks aren't strong enough for disc brakes. He was back tracking in the face of evidence that road bike forks are indeed strong enough for disc brakes by claiming that he meant the pure race bikes only. I wonder how many TDF riders thrashing down 100kph descents realise just how weak their bikes are!

 

[Piemaster]

Thinking about it, why would disc forks have to be stronger than road forks?

If two bikes, one with rim brakes, one with discs, stop in the same distance the braking force generated between the tyre and the ground is the same in both cases. Tyre/ground would be one end of a lever, the other end would be at the other end of the fork where it meets the frame - the headset. So type/position of the brake is actually irrelevent to bending moment applied to it.
The only reason I can maybe see for disc forks being more substantial is to actually provide a mounting point for the caliper. As the caliper is mounted on the rear of the fork the only bending moment will be between the caliper and the wheel centre, a short distance and obviously beefed up a bit anyway with the caliper mount.

 

[fossyant]

Discs on road bikes are just wrong. Simple. Ugly - ugly things are not allowed on road bikes !

Ideal though for crappy conditions - would be great on a commuter. I tend to eat rims on my fixed. I get about 18-24 months out of a rim.