Avid BB5 Disc Brakes - help/advice needed

[CopperCyclist]

I have the Boardman CX too, and have exactly the same issue. I took it back a few times to Halfords to get 'fixed'. Their solution was to adjust the brakes so that they were tight enough that you couldn't pull them far enough to snag. Of course, this meant the brakes rubbed like a bastard so you were permanently losing speed!

I wasn't happy with this, but lost faith in Halfords so set them up carefully and painstakingly myself to give maximum tautness on the cables with no rub. They still aren't perfect, if I pull them on hard on the drop brakes, the gear lever snags. I tend to try to do most of my heavy braking with the flat bar brakes instead. The brakes still work effectively, so it's to dangerous - just irritating to flick that shifter back out all the time.

I've just hit 2000 miles on the bike, and my chains approaching 75 percent wear. I've decided that when I replace the chain, I'll enquire about the price of some BB7's as well, and maybe get the LBS (not Halfords) to do the lot at once if it's affordable. Whether they will solve it or not, who knows, but I'm hoping it'll help.

 

[Globalti]

Changing from BB5s to 7s is not difficult - it's a simple swop.

 

[lejogger]

I went out yesterday on a club run... unfortunately the route changed last minute from a flat/rolling 100 miler through Cheshire to a knee popping 60 miler up and down the welsh hills and valleys. I was very nervous about going down some fast descents with my deteriorating brakes, and to be honest by halfway through I'd lost virtually all stopping power. It was horrendous. Spent the whole ride skulking at the back of the group, having to leave adequate room in case an emergency stop was needed... on some of the descents I was having to pull the bar mounted levers quite literally with all of my strength just to keep under control. (admittedly a lot of the skulking was due to the Xmas all-day real ale-athon on Saturday with the work lads!)

When I made it home I decided to spend half an hour in the garage having a serious look to see if the adjusments were something I could do rather than keep returning to Halfords. Even if I messed it up, at least I'd have a better idea of how the whole thing works.

Anyway... the upshot is that I dialed in the units to make sure the discs were the proper distance from the fixed pad, used the adjuster to bring in the adjustable pad a bit more... (was a good learning experience just having a fiddle around, was relatively simple - just a bit fiddly with the guards on). Was still left with the snappy brakes though because the main problem is the cable stretch. I completely agree with Cunobelin about the cheap cables... it appears that mine are made out of liquorice.

A quick tightening up of the cables and a check that the pad isn't rubbing on the disc when the wheel spins, and all of a sudden I've got absolutely fantastic stopping power again. To be honest, the front pad was rubbing slightly, but I'm happy that this will settle down after a good few big squeezes. I can totally understand swapping to BB7, but to be honest, if any investment is going to be made, then the cables must take priority.

 

[Globalti]

Having sat down and sorted my own problem last night I can see that for the first time the pads are sweeping the whole disc. Can you believe I've ridden the first 75 miles with the pads not in properly? Each of the four pads has got a slightly chamfered edge where it was being pressed at an angle against the discs, which were still un-scored and covered in fingerprints apart from a narrow band around the edges. No wonder the bloody things were howling on downhills.

Once I'd got the pads in properly, adjustment was simple and quick - no more annoying rubbing and good sharp brakes!

 

[Andrew_P]

Having suffered BB5's on an old bike when I bought a New Boardman CX the very first thing I did was get a pair of BB7 which I got for £100 the pair with 140mm rotors. Having spent a few hours trying to get the BB5 running and endured 150 horrible BB5 rubbing miles

Took me about half an hour to swap them and dial them in, and they are perfect, wheels spin with zero rub and come to a stop after a lot of time (BB5's seemed to rotate a few times before grinding ot a halt)

Braking is great in all weathers just have to remind myself not to yank them on or a go in to skids or worse still over the top!

 

[Globalti]

I'm psyching myself up for the weather on tomorrow night's MTB club ride as I'm going to take the CX along. It will be the first time anybody has done a club ride on a crosser so it will be fascinating to see how it performs against the full-suspension mountain bikes most people use. I chose tomorrow's ride because it is less of a mud-fest and takes mostly BWs and tracks and some tarmac roads. I'm feeling happier about it now that the brakes are working!

 

[GrumpyGregry]

My main reason for binning the BB5's on the tourer was any significant time spent off-road guaranteed they'd need fettling en route, say over the course of the weekend, and I found them too hard to adjust, with cold hands, in the rain, in winter.

 

[CopperCyclist]

You're all convincing me that I'm definitely swooping to BB7 as soon as my chain gets replaced, probably January! I'll ask for new cables too as I can see what you mean about them stretching way too much

 

[Globalti]

The swop won't cost you much if you flog the BB5s on Eblag. Mine are on there now and I had an offer by day 2.

 

[GrumpyGregry]

Talking of BB's does anyone know anyone who actually stocks the inboard red plastic adjuster disc thingy. If I can track a pair down I can sell my BB5's to an unsuspecting fool on eBay

 

[Globalti]

You will need to get one from SRAM.

 

[Pauln]

I have BB5 on my Boardman hybrid comp, I have done almost 900 miles on it and haven't done anything to the brakes at all and they have performed perfectly, must have been well set up to start with.

 

[Andrew_P]

You're all convincing me that I'm definitely swooping to BB7 as soon as my chain gets replaced, probably January! I'll ask for new cables too as I can see what you mean about them stretching way too much

seriously, if you are getting any rub, or no rub but really long lever travel switch to the BB7, CRC had the rear BB7 Road calipers on offer @ £50 each the only thing that makes them "rear" is that they are supplied with a 140mm Rotor which you can leave in the box. I am not a techie regarding bike mech but fitting and setting them up was a breeze. The only thing you will need is a decent wire cutter and two wire crimp on ends.

 

[Andrew_P]

I have BB5 on my Boardman hybrid comp, I have done almost 900 miles on it and haven't done anything to the brakes at all and they have performed perfectly, must have been well set up to start with.

If you spin the wheels can you hear any rub, do they free spin for a long time? Hybrids I would think will be using the longer travel BB5

 

[Globalti]

Who started this rubbish about brake cables stretching? The tension needed to apply any kind of brake is nowhere near enough to stretch a 1.8mm steel cable!

Sometimes cable outers will settle a little, especially if the ends weren't ground flat after cutting but in 45 years of fettling bikes I've never seen a brake cable stretch. Gear cables on the other hand might stretch as they're thinner (1.2mm) and the tensions are greater and constant.