Mates Debate: V Brakes vs Discs

njee20

Around 1.5lb weight penalty with BB7s, mitigated slightly with hydros, but there aren't too many weights floating around for direct comparisons.

I think the crash dangers are a bit of a red herring to be totally honest, there are lots are sharp sticky outy bits on bikes anyway!

supersonic

The UCI still ban tri bars on grouped races though. UCI though is a bloody dinosaur.

Wily-Quixote

The noise of disc brakes is their only downside, i reckon. Not enough of a problem to consider a return to V-brakes - which can still scream if set-up incorrectly.

kajjal

There are couple of differences in road and mountain biking. Mountain bikers when competing at any level don't tend to ride in huge groups. This means any accident takes out few if any other bikers. For road bikers the opposite is true. A mixture of road and rim brakes on road would be dangerous , especially in the wet.

The second is mountain bikers are more open to trying new technology as they tend to be younger and can also more easily see the benefits off road. Road bikers tend to be older and not that bothered. Either way for larger riders / riding in the wet rim brakes are very poor compared to disc brakes on road.

njee20

The UCI still ban tri bars on grouped races though

Sod all control riding on tri bars to be fair, and they're more sticky outy than disc rotors.

The Rookie

stubs wrote:

Whats the weight difference between a top roadbike rim brake and a top road hydro discbrake.

None in effect as they will both achieve the UCI min weight on a bike, for the brake swap it's hard to say, it's not just lever, hose/cable and calliper, it's the effect on rim weight (Disc should be lighter but is frequently heavier), hub weight (heavier), the disc weight and mounting to the hub as well.

njee20

Rim weight is very unlikely to change in any marked fashion as they're all on tubs, which are essentially a box section anyway, taking away the braking surface does nothing, it didn't really make a difference on clincher rims. 250g rims are commonplace on the lighter wheelsets, you won't get that down much. Frames and forks are heavier, plus the actual brakes are heavier, and all the additional hardware.

The UCI weight limit is irrelevant, as no one's racing in UCI races on discs, in 'cross, where you can draw comparisons the weight penalty is about 1.5lbs. You could build a disc-equipped road bike on the weight limit, but it would still weigh about 1.5lbs more than the equivalent bike with rim brakes!

larkim

If we're debating the roadie u brake vs MTB disc preference, surely part of it is that the thin contact patch of narrow tyre with 120psi pressure onto the road means that it is easier to lock up front or rear brakes on a road bike even with the lower effectiveness of brakes on the rims, especially on a wet surface. And also, braking is far less fundamental to speed on a "normal" road route (accepting that heading down a mountain at 50mph+ would require confidence in their stopping power, and possibly some advantages to riders with the most effective brakes).

kajjal

larkim wrote:

If we're debating the roadie u brake vs MTB disc preference, surely part of it is that the thin contact patch of narrow tyre with 120psi pressure onto the road means that it is easier to lock up front or rear brakes on a road bike even with the lower effectiveness of brakes on the rims, especially on a wet surface. And also, braking is far less fundamental to speed on a "normal" road route (accepting that heading down a mountain at 50mph+ would require confidence in their stopping power, and possibly some advantages to riders with the most effective brakes).

This is very true but disc brakes give better power and modulation which means later braking and more control overall. When I switched from VBrakes to disc brakes on my mountain bike I went faster due to being able to brake a lot later and also being able to hold the bike better on the limits of traction as well as correcting losses of traction very quickly. This still applies to road bikes but more for control and setting wanted speeds faster, rather than cornering on the limits of traction and correcting loses of traction.

larkim

I agree with the fundamental - disc brakes are better in all senses. But if the pro-roadies aren't clamouring for them (presumably because they don't believe the trade off of better braking against mild aero downsides and potential weight (or at least, weight distribution) increases) then why would the major manufacturers bother?

For a pro rider the ability to slow down is far less important than the ability to accelerate or maintain speed. I can imagine on many of the TdF flatter stages that some riders will not use the brakes at all across the whole day. Obviously, descending from the Alps is a different matter...

ilovedirt

You wouldn't believe how easy it is to lock up the back wheel on a roadie! I've not locked my front wheel up yet, and I'm kind of hoping I won't any time soon!

larkim

I guess the difference is that a pro-MTBer will need and use his / her brakes in the most aggressive* manner / at the highest speeds compared to a bog standard trail rider. Whereas a club road rider is much more likely to come across an idiot on the road and need to slam on their brakes compared to a competing pro road rider.

*Don't take me to task about whether "aggressive" is the right term, you know what I mean - their brakes are one of their essential tools to do their job, in a way which doesn't apply to pro roadies

Daz555

supersonic wrote:

The UCI still ban tri bars on grouped races though. UCI though is a bloody dinosaur.

Making riders more aero in road races would not help the racing spectacle - so I can't see any point in having them. It would not be used by riders within the mass of the peloton due to safety so the only riders on their tribars would be the ones at the very pointy end of the peloton or the handful of guys away in a break.

Air resistance defines the tactics of road cycling almost completely (aside from steepest climbs). Reducing the influence of air too much would reduce the spectacle.

The likes of Wiggins and Martin (TT specialists with superbly efficient TT positions) would no doubt get a few more stage wins were tri bars allowed on road stages but that's about it.

supersonic

Not that it particularly a spectacle anyway, but I guess that is personal opinion. However I like choice - I can see some safety arguments, however, pointy pedals and searing hot disc brakes have their arguments too.

I just don't understand the UCI regs. It's getting a bit F1.

Initialised

ilovedirt wrote:

You wouldn't believe how easy it is to lock up the back wheel on a roadie! I've not locked my front wheel up yet, and I'm kind of hoping I won't any time soon!

Don't, it hurts!

Now I'm using hydros on the road while it may be easier to lock a wheel intentionally I don't do it by mistake because there's so much more control and consistency between feathering the brake and locking up.

You really don't need that much of a downhill to get a bike up past 50mph on the road.

njee20

cyd190468 wrote:

The one reg that actually does make sense is the weight limit. Because they are limited you can go into a shop and buy a competative raodie for less than $2K (over here anyway). To race XC without a weight penalty you nedd to spend 3 or 4 times that amount.

That's one that doesn't make sense! Or at least could do with revision. It had merit when it was brought in in 2000, avoiding people drilling holes in things and what not, and maintaining a vaguely level playing field. It's led to people looking elsewhere for performance gains - aero bits, power meters etc, which I think is great, but it's too high now there are plenty of decent 800g frames and 1000g wheelsets.

The Rookie

I don't think anyone would argue against a loss of weight, if you add up the lightest components used now over a complete tour for each item you could probably drop the weight to 6Kg and still alllow people to tailor the weight to their individual needs (so sprinters have a heavier stiffer frame for example) without anyone suffering a penalty.

njee20

Your average club racer can actually afford to own a 7kg roadie but to be on par in xco land you need to run some very expensive gear.

I disagree, unless you only focus on weight, which is pretty pointless. Your average WC XCO bike is going to be £5-£7k, protour road bikes will be £10k+.

HellsCyclist

The biggest advantage of disc brakes imo is they dont rely on the wheel being true for great performance. On MTBs this could be an issue. The v brakes on my road bike are solid and easily capeable of locking the wheels. Obviously riding through mud and water then discs are better.
I currently have hydraulic brakes on my MTB and they are even sharper and solid than on any motorcycles Ive ridden (which also use hydraulics). How would cable operated disc brakes compare?

Northwind

HellsCyclist wrote:

The biggest advantage of disc brakes imo is they dont rely on the wheel being true for great performance.

Not the biggest but yeah, it is nice. Hardly any of my mtb rims are true and most of them have at least one decent size dent in them. Used to be such a pain in the bum with cantis.

njee20

cyd190468 wrote:

http://www.apollobikes.com/bikes13/carbon?id=2
Over here one of these are 4250quid. Sub kilo frame carbon rims sram red groupset. 6.5kg. I can't really see that this would slow you down. It's MTB equivalent is about 5000 but doesn't come with any of the race only stuff you see at world champs. If you look at the bikes in the pro peloton, half the price is the name in most cases. The Green edge guys are mostly on Scotts that you can buy for 5000. The down spec version is 2000 and still only weighs 7.1kg

Didn't say you couldn't get a 6.8kg bike on the cheap, just that it's not the same as a pro tour bike. You can buy a Canyon which is closer to a WC XCO bike for less than any true Pro Tour replica, you don't have the ultra-expensive stuff in the same way on MTBs. Taking your example - yes you can buy a Scott Foil for £5k, but OGE use Dura Ace 9070 Di2, and SRMs, with Dura Ace carbon wheels. No way in hell will you get that lot under £10k.

stubs

Especially not as pro roadbike frames are usually custom made. When Sky got some bikes nicked I am sure I read they cost on average £28,000 each.

njee20

They often have subtly different geometry certainly - notably shorter head tubes.

ravenvrider

Interesting thread, i have a 1999 Cannondale Raven Mk2 which came with V brakes, in 2005 i upgraded to Hope Mini's discs after which i rarely rode the bike but over the years almost every time i have the bike had some form of disc rub that was very noticeable when riding, i never had a problem with V brakes i just thought at the time discs would be better.

A few weeks ago i had enough after having the brakes serviced i still had problems. i ripped them off and went back to V brakes (Avid 7's), so far i have had no problems and find the braking very similar to my old discs.

I do not ride my mtb much in the winter so am not bothered by discs better ability in the wet, for me V brakes work well, are a lot lighter and easier to maintain especially on rides should problems occur.

Now my bike looks purely retro...

Northwind

To be fair that's going to be mostly down to them being an old and really not very good brake.

njee20

Yes, wheels.

You can say the same of MTBs - Chinese carbon frame, XX1 groupset, LB wheelset, SID fork. World Cup standard bike for £3k. Doesn't make it an S-Works Epic.