Disc brakes on road bikes

[MacB]

One suspects that a damaged disc on tour is a bit of a showstopper. Especially if you're thousands of miles away from your favourite road cycling beautique.

if they're mechanical discs brakes then carrying a spare rotor and even caliper wouldn't be an issue, depends how loaded/self sufficient you want to tour. You can also make a similar argument around touring with a rohloff(I'm a fan by the way) as it's not exactly and everyday repairable item. Then there's do you tour on a 26" or 700c wheelset? I like the move to disc brakes and can some benefits across the board:-

road disc wheels, touring disc wheels and 29er wheels are pretty much interchangeable

unlike rim brake frames disc brake ones don't care about wheelsize, in a pinch you could utilise a variety of wheelsizes from 20" up to 29" to get you home/to next bike shop. It's also possible to design a frame that will work well with 26" up to 700c assuming you use the smaller wheels for bigger tires and vice vera. This would keep the geometry fairly static so you could have a frameset that you toured on with 26" 2" tires and used on the road with 700x25 wheels/tires.

rotor failure on a disc brake doesn't make a bike unrideable you can just remove the rotor, not so with a rim failure.

 

[Beebo]

A mechanic from one of the big tour teams made a salient point that it is not very desirable to have spinning metal rotors(blades) because they'll cause real serious carnage in a crash(very common in racing).

I wonder why they allow them on racing motorcycles then, which can go barrelling down the road at 200 mph? Nobody ever wanted chainrings banned on bikes because the teeth might slice someone's leg off

The disk is much thinner and much more exposed in cycling, especially the front disk. The rear disk is protected by the rear triangle, as is the rear cassette. Plus the riders arent wearing thick leather either.
I have disk brakes on my road bike, and a guy in the bike shed was amazed at how thin my disk was compared to his MTB disk. It realy is a bit like a circular saw.
You wouldnt want to be hit in the calf at 30mph by a spinning front disk.

 

[MacB]

I wonder if there is a system that could provide the benefits of disc brakes and remove some of the drawbacks - how about drum brakes?

Or they could just create an aerodynamic carbon shell that fits over the front disc as a safety precaution, maybe for race use only?

 

[Vapin' Joe]

One suspects that a damaged disc on tour is a bit of a showstopper. Especially if you're thousands of miles away from your favourite road cycling beautique.

You wouldnt want to be hit in the calf at 30mph by a spinning front disk.

To be hit on the calf by a disc which is mounted inboard of the fork your leg would have first had to go through the spokes of the front wheel. That's the most ridiculous reason I've heard for not wanting to adopt new technology, and I've heard all the scare stories from indexed gears through clipless pedals and brifters, plus all the rest.

 

[Beebo]

To be hit on the calf by a disc which is mounted inboard of the fork your leg would have first had to go through the spokes of the front wheel. That's the most ridiculous reason I've heard for not wanting to adopt new technology, and I've heard all the scare stories from indexed gears through clipless pedals and brifters, plus all the rest.

No it wouldnt, you could easily get a glancing blow from the tyre, straight into this.

 

[Bodhbh]

One suspects that a damaged disc on tour is a bit of a showstopper. Especially if you're thousands of miles away from your favourite road cycling beautique.

I've had v few problems with discs on tour. Well two: after pushing the bike several hundred meters thru thick clay, I managed to scour out the pads. My fault really for trying to go thru stupid crap, rim brakes would prolly have just locked the wheels with clay due to lack of mud clearance and I'd have had to gone another way. Other time, the pad retainer pin fell out, and so did the pads. My fault again for not bending the pin properly. I've yet to have a bent disc or them fail altogether tho. In fact the Shimano M525s are the only things left from the orginal build after 6-7 years swapping out other bits either due to brakage, wear out or upgrades.

You do have two brakes afterall to limp to the next port of call. Also front and back racks make a makeshift around the discs. And as MacB says, is it really any more likely than bending the rims out of true, either thru wacks or spokes pinning (which can happen a fair bit on tour if you're wheels aren't properly built). Sorry, thread derail....

 

[Globalti]

You wouldnt want to be hit in the calf at 30mph by a spinning front disk.

This is absolute nonsense. If you've just fallen off your bike at 30 mph the spinning disc is going to be the least of your worries. And just how do you suggest that your body might come into contact with the disc anyway?

Posts like this are as daft as those from people who objected to wearing seat belts because they feared getting trapped in a burning car.

 

[Beebo]

This is absolute nonsense. If you've just fallen off your bike at 30 mph the spinning disc is going to be the least of your worries. And just how do you suggest that your body might come into contact with the disc anyway?

Posts like this are as daft as those from people who objected to wearing seat belts because they feared getting trapped in a burning car.

You clearly havent understood what I was saying.
This is about racing in mass events, when the whole peleton comes to a crunching stop, the guy in front puts his right foot down, the guy behind crashes into his calf with the left side of this front wheel.

 

[Globalti]

Well then the front wheel would be stopped, wouldn't it? Mountain bikers fall off lots more than roadies but I've never seen an injury caused by a disc brake.

 

[MacB]

No it wouldnt, you could easily get a glancing blow from the tyre, straight into this.

Beebs I know you mean well but I'm just not getting shock, fear and awe from that image

 

[Vapin' Joe]

Well then the front wheel would be stopped, wouldn't it? Mountain bikers fall off lots more than roadies but I've never seen an injury caused by a disc brake.

Exactly. There's more chance of getting a brake lever through the neck than getting your leg severed by a disc and I've never seen that happen.

Within a few years of the UCI approving discs rim brakes will be history and we'll no more miss them than we do cottered cranks.

 

[boydj]

Cable discs are a faff to set up and need regular adjustment, hydraulics are fit and forget.

One thing both systems do is torture spokes - all the braking force goes through them.

Not a problem on hybrids which tend to have heavier built wheels and a high spoke count.

Could be a problem on a racer with ultra light wheels.

I would be interested to hear from disc brake road bike owners if the wheels/spokes appear to be built for the purpose.

The answer is to have wheels which are built to take the stresses of disc brakes. CX bikes tend to use mtb hubs with 700c rims. My own wheels have Hope hubs and Archetype rims with 32 spokes. I'm pretty sure that some of the new road disc wheels that have been introduced recently will have found ways to minimise weight while maintaining strength.

 

[T.M.H.N.E.T]

The answer is to have wheels which are built to take the stresses of disc brakes. CX bikes tend to use mtb hubs with 700c rims. My own wheels have Hope hubs and Archetype rims with 32 spokes. I'm pretty sure that some of the new road disc wheels that have been introduced recently will have found ways to minimise weight while maintaining strength.

What have MTB wheels been all these years then if Pale Riders post is such an issue?

 

[boydj]

What have MTB wheels been all these years then if Pale Riders post is such an issue?

Good point. But then you don't see low spoke counts on mtb wheels and the shorter spokes do make them inherently stronger. I'm sure the road guys will be testing the limits on weight vs the strength required for road riding. It would seem to be only a matter of time before we see the professional road teams on disc-braked bikes, given the rate at which new models are acquiring disc brakes..

 

[MacB]

given the rate at which new models are acquiring disc brakes..

that's the telling point for me, I can't see any way they'd be ploughing ahead in this manner if they didn't know it was coming