if Shimano road mechanical disc brakes are any good?

[niggle]

I am looking at road mechanical disc brakes for my Kaffenback build, and of course the Avid BB7 is the popular choice, but there are alternatives even with dual pad adjustment such as Shimano CX77 or R517 (the latter priced a bit lower and looks suspiciously like it is the same as the more expensive one, just 105 rather than Ultegra). Why are these not popular?

Even cheaper is the single adjustable pad design Sora R317- why would this not be a perfectly good cheap alternative to a BB5 on the rear? I have a Tektro Io single adjustable pad front disc brake on my commuter which was salvaged from a skip bike and works just fine now I have learnt how to set it up, best brake I have on any of my bikes apart from screeching in the wet- will have a look in to that issue shortly.

EDIT: also not quite sure whether they are compatible with my Sora 9 speed STIs- descriptions say compatible with 'Super SLR' brake levers, which I think is current Tiagra and up and means slightly more cable pull, though not as much as V or MTB disc brake cable pull???

[RogerThat]

They're excellent, had a go at them last weekend on a clubmates bike, massive stopping power and quite progressive too.

[Sweep]

I seem to remember from a visit of mine two or three months ago that the highly regarded Brixton Cycles recommend a Tektro disc brake model for their Surly Disc Trucker builds. They had a particular reason for this but am afraid I can't remember it. Nor can I remember the model number.

[niggle]

Just found a seemingly quite sensible review which says that the cheap Soras are just fine, just weigh about 30g more: http://tractionbikeblog.com/2015/01/05/ ... sc-brakes/

The Soras are £21 each at CRC, though that does not include rotors or adapters.

Actually by this logic BB5s are probably fine as well and are £18 at CRC without rotors or adapters. I have one spare 160mm rotor and adapter from the skip bike, and rotor prices start at £4 at CRC.

The Tektro road disc brake mentioned by LBS is probably the Lyra, which is also dual pad adjustment and priced similar to the R517s

[Dave W]

I have BB7's on the Tandem, Sram Elixr on the mountain bike and BB5's on the wife's bike.

.................... oh, how I wish I'd saved up and bought the disc brake version of my new Cannondale Synapse - rim brakes are so poor in comparison.

[Norton]

My Bike Friday came with them (R517). as standard.

They certainly stop you, but so far I can't get them set up to bite early enough in the lever travel for me and without the pads rubbing the rotor slightly; by contrast I've had no problems with BB7s at all. Maybe I haven't given them enough attention, but would probably advise sticking to bb7s.

[niggle]

My Bike Friday came with them (R517). as standard.

They certainly stop you, but so far I can't get them set up to bite early enough in the lever travel for me and without the pads rubbing the rotor slightly; by contrast I've had no problems with BB7s at all. Maybe I haven't given them enough attention, but would probably advise sticking to bb7s.

In my very limited experience with the Tektro Io brake the trick has been to get the caliper aligned to the disc by loosening the caliper mount bolts, holding the brake on firmly and re-tightening the mount bolts, then back off the pads just enough to stop the rubbing. Should be easier with the dual pad adjustment of the R517 and also it pays to make sure the actuator arm is at about a right angle to the caliper when the brake bites.

Once I did all this the lever travel came good with no bottoming out and the rubbing reduced to a minimum- the wheel spins freely and you just hear a very slight tickle sometimes if listening carefully. The braking power has also improved with bedding in over time and now it is the most powerful and progressive brake I have.

I have bought one used R517 from Ebay for £10.30 posted and ordered a BB5 from CRC so will be able to make some comparisons, but not until I have built the wheels for the Kaffenback.