Mechanical disc brakes

[danphoto]

As in Shimano M416. What's the pros and cons of these for commuting/pootling round the countryside?

In other words one bike I'm considering is the Trek Valencia which has these, compared to the broadly similar 7.3FX at £50 less which doesn't, and I have no idea if they're a plus point or not.

Oops - sorry folks, just answered my own question

 

[Bigtwin]

I had those on a Raleigh Special Projects bouncer.

They were awful. Far less stopping power than a decent rim set up. Only plus was that around here it's very sandy and thus hard on rims, which gives any sort of disc some form of purpose.

Some say mech discs are more robust than hyros on the basis that it's harder to break a cable than knacker a line. Personally, I think that so long as you run your lines sensibly (back of forks etc) and don't have them flapping around looking for things to get snagged on, it's a non-issue. But that's just my 2p.

 

[willem]

Decent Shimano v brakes such Deore are excellent, and really all you need for this. But use good pads such as Koolstop. If you want to spend a little bit more go for better levers. Next step up is Magura hydraulic rim brakes, (love them, but they are luxury). Discs on bikes such as these are an initiative of the marketing department. That is why I don't like this kind of bike. For a different take on what practical bikes should be, look at the Fahhradmanufaktur range. They are the brand of a chain of independent German bike shops, and they are designed by cyclists for cyclists: http://www.fahrradmanufaktur.de/ Nice steel frames, most models without suspension, enough spokes in the wheels, good tyres, quality racks and lights, etc. Not made in China either. I understand some UK shops also sell them
Willem

 

[danphoto]

Gosh Willem, thanks for that link. They look amazing. Now to get the lady wife on that site and do some serious translation for me

 

[jig-sore]

i never really understood disc brakes on a bike, the only plus i can see it that they keep the braking surface out of the mud, only good for mountain bikes.

in reality is a wheel rim not just one massive brake disc ??? and the further way a force is applied from a pivot the greater it becomes so in reality bike wheels are a very effective form of a disc brake ???

so why replace it with a really small one ?? someone explain please

 

[Bigtwin]

i never really understood disc brakes on a bike, the only plus i can see it that they keep the braking surface out of the mud, only good for mountain bikes.

in reality is a wheel rim not just one massive brake disc ??? and the further way a force is applied from a pivot the greater it becomes so in reality bike wheels are a very effective form of a disc brake ???

so why replace it with a really small one ?? someone explain please

For road bikes, the only advantage I can see is that discs are better in the wet - I can see the point for winter commuting perhaps.

Interestingly, motorcycle manufacturers are not catching onto the exact point you make. Rim discs are now being fitted - "radial" as they are calling them.

 

[summerdays]

Cleaner (none of that grey sludge that once was your rim), stops better in the wet/mud etc, don't need to keep adjusting them as they wear. And as I discovered after I broke my arm, they don't need as much strength to pull either.

My downsides are that I'm getting a brake judder through the frame at the moment, and that they squeak or even squeal occasionally.

 

[GrumpyGregry]

i never really understood disc brakes on a bike, the only plus i can see it that they keep the braking surface out of the mud, only good for mountain bikes.

in reality is a wheel rim not just one massive brake disc ??? and the further way a force is applied from a pivot the greater it becomes so in reality bike wheels are a very effective form of a disc brake ???

so why replace it with a really small one ?? someone explain please

your analysis of wheel as brake disc is sound. So why bother with discs; simply put because they work better than rim brakes. Lots of riders don't volunteer to ride their road bikes in the rain. If they do they find their braking, with rim brakes, canti's V or caliper, severely impaired. Discs work much more consistently wet or dry. some of us ride rain or no.

using the wheel rim as a brake means that you wear out the rim from braking ultimately meaning you replace the rim. this wear is accelerated if you use the brake in mucky conditions, and if you ignore wear remember that rim failure is likely to be catastrophic.

using the rim as a brake means the rim gets hot, on a heavily loaded bike, with a big rider, on a long descent (eg alpine) using a maybe less than optimal braking technique this rim heating can cause your tube to go 'pop'. Been there, done that. This is why classy tandems normally have some form of rear drag brake that doesn't involve the rear rim.

using the rim limits the size of the braking surface to the width of the rim with discs you get a larger braking surface and can change the effectiveness of the disc by increasing the size of the disc easily and cheaply.

discs aren't perfect but my guts say you are going to see more and more of them on road going bikes in the future.

 

[Cubist]

Again it depends on usage and quality. I personally think mech discs are a waste of time, and as others have said, a marketing gimmic. A good quality pair of rimbrakes will do all that you ask of them on a dry road, as long as you keep them well-maintained. However, add luggage, steep hills, muddy towpaths, off-road wet/muddy trails, and you soon start to see the advantages of hydraulic discs. I wouldn't want to do any serious trail or XC without them.

I've spent the last couple of weeks trying to decide what to get on the C2W scheme, and have decided on the Boardman hybrid pro. I want to be able to commute in all weathers, live on a steep hill, want to do a bit of light touring and some sociable riding at a reasonable pace. . The bike seems suited to all of that and what's more has Avid Elixir brakes. So yes, they do have a practical application for road bikes.

To answert the OP's question I can throw in two factors. Rimbrakes will probably do all that mech discs will do, so the extra £50 for mech discs is not worth it. But. If you plump for the mech discs you will have a frame and wheels ready for upgrade when you've saved a bit of money for some quality disc sets.

 

[jig-sore]

wow, great answers everyone, thank you, i kinda see the point a bit more now

 

[GrumpyGregry]

cubist - maybe you've never ridden a bike with properly set up Avid BB5's or BB7's then?....

No way are mechanical rim brakes as effective or consistent, ime, across a whole variety of conditions as BB7's - the only rim brake that comes near are Magura's.

YMMV

 

[Cubist]

cubist - maybe you've never ridden a bike with properly set up Avid BB5's or BB7's then?....

No way are mechanical rim brakes as effective or consistent, ime, across a whole variety of conditions as BB7's - the only rim brake that comes near are Magura's.

YMMV

No you're right. My only experience of mech discs has been on cheap end MTBs or even kids' bikes. I'll stand corrected if you're telling me that there are some out there that will work well. Come to think of it the Boardman Comp has BB5s, and I somehow doubt they'd be crap!

 

[RedBike]

Avid BB7 brakes changed my view on mechanical disc brakes.

They work really well.