Disadvantages of disc brakes?

[Fnaar]

I may be buying a new tourer and I've narrowed it down to 2 potentials. One has discs, one has regular rim brakes. To be used primarily for commute, with light loads, and occasionally for longer tours (nowt drastic) with heavier loads. I've never had discs before, and was wondering about the pros and cons.

 

[ColinJ]

Well, watch you don't touch a rotor with your leg after braking on a long descent! (It's a mistake that you will probably only make once ... )

The fluid in the closed hydraulic system on my MTB brakes heats up and expands on long descents and tends to lock the brakes on but I think that is an unusual problem. (Old Hope C2 brakes.)

 

[Jmenorton]

I really cant see a disadvantage for discs, weight maybe although not a concern on a tourer. They occasionally squeak in the wet. I think all my future bikes will have discs. Got BB7s on my current Road/CX bike and there fantastic in all conditions.

 

[Sara_H]

I've had hydraulic discs for about a year now, and I've found I prefer them, they seem more efficient and less prone to suddenly throwing themselves out of adjustment for no apparent reason!

 

[Red Light]

Well, watch you don't touch a rotor with your leg after braking on a long descent! (It's a mistake that you will probably only make once ... )

That's why you need a good brand

The fluid in the closed hydraulic system on my MTB brakes heats up and expands on long descents and tends to lock the brakes on but I think that is an unusual problem. (Old Hope C2 brakes.)

I have those and they are fine, On long descents just twiddle the caps a bit to back them off as they heat up and then in the other direction as they cool down. I marked a couple of black arrows on the caps so I could see how much I had adjusted them and reverse it.

 

[GrumpyGregry]

The disc rotors are fairly easily bent, and not so easily straightened again, especially in falls or by clumsy baggage handlers (or the bloke on that train once....)

The disc pads for some calipers are not that commonly available so carry your own spares.

But I wouldn't tour loaded on anything else.

(BB7s (grey road version) since you ask)

 

[ianrauk]

I really cant see a disadvantage for discs, weight maybe although not a concern on a tourer. They occasionally squeak in the wet. I think all my future bikes will have discs. Got BB7s on my current Road/CX bike and there fantastic in all conditions.

This.
Have BB7's on my commuter (Kona Honky). Now won't have a commute bike without disc brakes.
They do squeal in the wet.. but I can live with that.

Advantages for me.
No rim wear.
Better stopping in the wet.
No black brake dust gunk.

 

[ColinJ]

That's why you need a good brand

I get it! In fact, I almost did end up with a permanent scar on one calf. I was amazed at how hot the rotor had got.

I have those and they are fine, On long descents just twiddle the caps a bit to back them off as they heat up and then in the other direction as they cool down. I marked a couple of black arrows on the caps so I could see how much I had adjusted them and reverse it.

Well, maybe my descents are a lot longer and steeper than yours because I use the entire range of adjustment and can still end up with the brakes locked hard on until they cool!

I was searching for information on the problem a few minutes ago and one person suggested that bleeding a few drops of hydraulic fluid out of the system might be the answer. I don't mind adjusting the brakes on a descent but it is literally a showstopper when I run out of adjustment.

There is one particular local descent that I get to within 50 metres of the bottom of when the brakes start to overheat. If I'm careful, I can just get to the bottom and carry on.

One thing that has caught me out a few times is forgetting to adjust the brakes back the other way as they cool down. 10 minutes later, I go to brake and nothing happens!

 

[Cubist]

I had them on my Boardman commuter, and they were just awesome in any weather. Modern hydraulic brakes are fit and forget, but BB mechanical ones will need a a bit of adjusting, but no more so that rim brakes.

 

[MacB]

As per others - you do read of dire warnings if touring in remote parts but then you just make sure you have spare bits. Rotors can get bent but truing them isn't hard and, if beyond that, they can be replaced very easily.

Personally I have stuck with the mechanical BB7s both road and MTB versions because I feel more confident maintaining them. Also it means I have the same spare parts covering the brake systems across 5 bikes.

 

[byegad]

If you have a long descent with a full load you need to watch disc temperature. There is an outside possibility that you can warp a disc although I've had no issues even in the North York's Moors where 33% gradients lurk.

 

[Red Light]

Well, maybe my descents are a lot longer and steeper than yours because I use the entire range of adjustment and can still end up with the brakes locked hard on until they cool!

I was searching for information on the problem a few minutes ago and one person suggested that bleeding a few drops of hydraulic fluid out of the system might be the answer. I don't mind adjusting the brakes on a descent but it is literally a showstopper when I run out of adjustment.

There is one particular local descent that I get to within 50 metres of the bottom of when the brakes start to overheat. If I'm careful, I can just get to the bottom and carry on.

One thing that has caught me out a few times is forgetting to adjust the brakes back the other way as they cool down. 10 minutes later, I go to brake and nothing happens!

You just need to go a bit faster and use the brakes a bit less

I have never run out of range and I do some fairly technical riding in places like the Lakes, Yorkshire and Peak District to the point where I have blued the rotors a number of times from the length and strength of braking. How many turns of the caps do you have from fully out to where they are clamped on the rotor? If its not many then you might try the following. Dial the cap in one turn, then open the bleed nozzle, let the excess fluid out, then tighten it up again. That will reset the "brakes off" point to one turn in rather than fully out and give you an extra turn of adjustment when they heat up. You can do more than one turn if you want. The only limit is having braking available when you go out and its a cold day - especially with winter coming and leaving some to be able to adjust for pad wear.

 

[Peteaud]

My hybrid / commuter / do it all has discs (Shimano Deore) and they have been fantastic.

My Trek MTB has Avid and they are useless. Take a wheel off, and lay the bike on its side for a car trip in the boot and i have to reset them, they bind when hot, ive replaced the domed washers twice due to cracking, hate the things. They will get replaced with Deores when possible.

Road bike - Sora brakes, brill.

 

[Fnaar]

Ees gettin compulicated... Rim brake bike is cheaper, so probs go with that. Thanks for your thoughts, peeps!

 

[billflat12]

Using disc brakes is definitely the way to go considering the uk climate , go disc & you,ll never look back ,
Although more expensive hydraulic systems are more reliable as there,s no cable to stretch or clog up.
Think hope,s C2,s are the only closed system( ie.without a reservoir for oil expansion ) , that,s why the inevitable usually happens as they get hot , open systems can suffer brake fade if they overheat though, usually with small rotors and a long descent , main disadvantages is when you grab a handful you can easily lock up , or pad availability ( there.s no common standard like rim brakes)
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