Disadvantages of disc brakes?

[subaqua]

I have hydraulic rim brakes on my commuter (Magura) I still prefer the Hydraulic discs on the MTB for sheer stopping power.

 

[byegad]

Only ever experienced brake fade from overheating disc brakes with small rotors ?, main disadvantages are if you grab a handful you can easily lock up , or pad availability while on tour,
These Q&A covers most http://www.mtbr.com/discbrakesfaqcrx.aspx#equipment

Yes pads can be hard to find, but sticking a couple of pairs in your kit adds very little weight.

 

[ColinJ]

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.

Sounds like a plan!

I won't be riding the bike again until the Spring because I'm pretty ill. I also don't ride offroad in very cold conditions any more after some heavy crashes on ice in years gone by.

I can't remember exactly how many degrees of movement I can get from the caps. I'll check when I come to look at the bike in the Spring. I'll give it a good fettle in the NY before I start riding again.

I always thought that the problem was a bit more severe than it should have been but never thought that I might have surplus fluid in the system. I basically only get about 250-300 vertical metres of technical descent before the brakes lock up.

As for braking less ... I'm at the limits of my nerve and ability already so I don't want to go any faster!

 

[HovR]

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 did this when I first got discs after my first long descent on them. "I just need to adjust the brake.." queue rotor shaped scar burnt in to my hand, including the holes in the disc and everything.

Haven't done it again since.

 

[Blue Hills]

I asked Paul Hewitt about this when speccing a tourer. He advised against it and said you needed a stronger fork. Not sure how much of an issue that is. I do know that he has built disc-braked tourers for folks - I've seen at least one.
Am currently for slightly complicated reasons using an old hybrid as an occasional tourer - I've been down some pretty steep descents with it's old shimano cantilevers loaded with 4 panniers and a load of junk on the rack and I didn't have any real problems. Of course my rims may have become a bit thinner and cleaning rims can be a a bit of time-consuming - though kind of theraputic.

 

[MontyVeda]

personally i can't see the piont of <edit>upgrading to</edit> discs. My rim brakes slow down stop the bike perfectly well, I've never had a problem with rim wear, and bearing in mind my front wheel is a good 17 years old... I don't see it as an issue.(back wheel lasted 17 years too, but split at the join a few months back)

I may not clock up tens of thousands of miles a year, but i use my bike daily so do get plenty of miles in (it's a vehicle, not a hobby).

does a brake on the rim have better or worse stoping force due to it being near the outside edge of the wheel as opposed to a small disk near the middle? or does it not matter?

 

[andrew_s]

A disc brake will stop the bike much better than a rim brake if it's raining much.
Rim wear can be a problem if you ride a lot on small lanes in all weather, and use the wrong brake pads. My record is about 8 months (6000 miles). Old rims were more substantial than modern lightweight rims are, and so lasted longer.

Hydraulic brakes aren't available for drop handlebars.

On most bikes the front disk is mounted on the rear of the left fork blade. In this position, it is possible for the brake to twist the wheel out of the dropout despite the QR and your weight, and cause a crash (probably nasty).
You have to have lawyer lips on the dropouts, and use a strong QR (i.e. Shimano or Campag ONLY) done up very tight, and check the tightness regularly. It's better to have the QR lever at the disc side too.
Consider this to be the risk equivalent of a worn front wheel rim failing and causing a blowout.

I regard being able to stop on demand in the wet to be my main priority, and therefore my most recent bike has discs (BB7).

 

[byegad]

I have BB7s on two of my trikes and love them, but then I also love the SA drums on my QNT.

 

[billflat12]

Hydraulic brakes aren't available for drop handlebars.

There,s the TRP parabox that uses your existing levers
Thankfully since the uci dropped the disc ban in cyclo-cross.momentum for hydraulic is now gathering , we brits do like to stick with tradition so tend to be slower in embracing discs fully.

Fnaar ,can i ask what particular model you had in mind ?

Plenty of traditional drop bar steel tourers available with discs from well under £1k
E.B.C.,s Revolution Country Explorer
Genesis Croix de Fer
Charge Filter Hi
Raleigh Sojourn
Surly disc trucker
Kona sutra

 

[Yellow7]

The disadvantage of rim brakes is they obviously wear down the rim. I’ve just [reluctantly] brought 2 new rims for my tourer (DRC MT19), although the wheels were still running dead true & had never popped a spoke I felt after 18000 miles replacement would best before the next big tour to Singapore. When I built the bike disk brakes were preferable, although [at the time] the SON front hub dynamo was never made with to accept disk brakes.
Hydraulic disk brakes offer excellent breaking power, something required on an off-road trails or down-hill bike, but not really required on a touring bike. Should I ever build another bike I would use & recommend mechanical (cable) disk brakes, this as stated above eliminates the need to replace rims on what is other-wise a good wheel.

 

[Nigeyy]

My Top Ten Disadvantages:
i. expense -good discs brakes don't just cost more -it's the disc specific hubs and rims that also can add cost (admittedly assuming you are upgrading not buying new as you are)
ii. weight -more stuff to carry as generally disc brakes will weigh more that a set of cantis or vs
iii. wheel strength -dished wheels necessary for disc hubs inherently make for a weaker wheel
iv. complexity -disc brakes aren't as simple as rim brakes (particularly if they are hydraulics) and of course, the more complex something is.....
v. rack and mudguard issues -on some bikes the disc brake mounts are set on the top side of the seat stay (i.e. as traditional disc mtbs are) and because of this interference this means you need disc specific mounts
vi. limited choice -road style handlebars? Your options are limited.....
vii. compatibility -you can't necessarily just use any old levers with them (i.e. if they are hydraulics).
viii. exposure -discs can be exposed more to dings or when packing the bike.
ix. maintenance cost -hydraulics will cost more to maintain (assuming you pay someone) and pads can be more expensive than their rim brake counterparts
x. accessibility -disc parts aren't usually found in an old hardware store or superstore -rim brakes parts can be, or even found on other bicycles.

Having said that, I have a tourer with Avid BB7 discs on and love them (wouldn't go back). While all the above are disadvantages, realistically and practically, they aren't valid or enough of a reason to give up the advantages I have.

 

[Yellow7]

My Top Ten Disadvantages:
iii. wheel strength -dished wheels necessary for disc hubs inherently make for a weaker wheel

Any derailleur based wheel is dished, be it disk or rim brakes. This is due to the derailleiur’s cassette mechanism increasing the space from drop-out (where the axle sits on the frame) to the spoke-ring on the hub, relative to the left-hand drop-out, as a result shorter spokes are used on the derailleur side, hence the term 'dished'.

(The more gears on the cassette naturally increasing the gap from drop-out to spoke-ring, shortening the spokes even more, as a result the wheel’s spoke tension (left to right) is not balanced, making the wheel weaker than one with a hub gear)

 

[Blue Hills]

(The more gears on the cassette naturally increasing the gap from drop-out to spoke-ring, shortening the spokes even more, as a result the wheel’s spoke tension (left to right) is not balanced, making the wheel weaker than one with a hub gear)

and as a slight side issue, sometimes the thing has to be dished more than you need - I've got a very solid late 90s steel hybrid I use as a tourer sometimes - 7-speed cassette and it performs just fine with only very occasional walking up the steepest of hills when fully loaded - but because decent 7-speed freehubs can no longer be had, its handbuilt wheels had to be over-dished only for me to then put a spacer on to accommodate the 7-speed cassette. grr, madness I tell you

 

[srw]

Any derailleur based wheel is dished, be it disk or rim brakes.

Not strictly true. One of our tandems has an undished derailleur rear, with a disc. I agree it's rare.

 

[Yellow7]

Not strictly true. One of our tandems has an undished derailleur rear, with a disc. I agree it's rare.

OK, the manufacturer obviously took into account the additional weight of the stoker, a well designed bike then.