Mechanical disc brakes

dilemna

I would like to convert my hybrid bike (currently 700C) from V brakes to disc. However I also want to try drop handle bars. Also I imagine mechanically operated calipers would be more reliable and easier to service than hydraulic disc brakes (which would need bleeding) which might be difficult when touring in far off remote places. I anticpate having a disc mount welded onto the rear of the frame and maybe onto the front forks if I can't find a suitable replacement fork.

The only model of mechanical disc brake I can find are the Avid BB7. However there appear to be two types 1) for MTB and 2) for Road. Is there actually a difference or is the difference merely cosmetic? Is the mechanical pull from MTB levers (eg Deore) different from that from STI levers (eg Ultegra)? If so this makes it a real bummer to switch from MTB levers to STI levers and vice versa if swapping from flat to drop bars and vice versa without changing the caliper itself.

http://www.evanscycles.com/products/avi ... t-ec024612

http://www.evanscycles.com/products/avi ... e-ec024614

Any advice appreciated.

boblo

Yes it's a problem. the MTB ones are for V brake lever pull and the road ones for STI/road brake lever pull.

Why not get the MTB calipers, a pair of Tektro 520 or Dia Compe 287v road brake levers (they both have V lbrake pull) and a set of bar end shifters? You could then change over to MTB type brake levers if you wished to swap to and from drop bars to flats.

The other way is to use the MTB calipers with Travel Agents/STI levers if you must go the brifter route.

Personally I'd go for the bar end shifters especially if you're worried about toruing in far flung places. They are simpler than brifters and therefore less likely to go wrong.

dilemna

Thanks for your advice. Some good tips and something to think about. I might just go for the MTB versions, but then again ..........

boblo

Beware, brifters don't work well with V's (or MTB Calipers), they don't have enough cable pull.

MichaelW

Disc brakes transfer forces around the bike differently to rim brakes. You need a stiffer fork so just brazing on an ISO mount will not be sufficient.
Some more progressive builders put the ISO mount on the leading edge of the right fork blade. This reverses the force on the axle from pulling it out to pushing it in. Useful if you are using standard quick-release skewers with no Lawyer Lips. Never use with lightweight external cam skewers.
At the rear, you may want to put the mount on the chainstay so as not to interfere with rack and mudguard eyelets. You may need to reinforce the frame with a strut between chainstay and seatstay. You also need to consider the cable routing.

ride_whenever

If you want to do this properly then either get a disc brake equipped tourer or build one up around a 29r mtb.

To be honest you're looking at a new set of wheels (or a rebuild) and a LOT of frame/fork work. It may well be cheaper to buy a new bike once you start looking at the deeper costs involved.

Personally I'd much rather go down the hydraulic route than the cable route purely because they are far less maintenance, and providing you've fitted new pads you're incredibly unlikely to suffer issues if using a good quality brand.

As for lawyer lips and external cams, i wouldn't worry about it too much...