Avid BB5 or BB7 Disc Brakes?

[Dtcman]

I have ordered a a Planet X audax bike on a fantastic deal so no option to swap out/upgrade parts. It comes with Avid BB5 cable discs and although I've never used either, I understand BB7's are far superior and would of upgraded if I could.

I'm debating weather to swap them out for BB7's before I use it or not.

Any thoughts?   


also, why are BB7 road calipers far more expensive that the MTB version, is it just supply and demand?

[PaulF]

I've got BB7's on both road and mountain bikes and I'm happy with them. As you can't change them at this stage I'd see how you like the BB5s before making a decision. Not familiar with the 5's but I understand the 7's are easier to adjust.

[rafletcher]

Havre a read here...

https://whosatthewheel.com/2017/05/05/mechanical-disc-brakes-a-review/

[L CC]

BB5 are crap

/considered review

[Torslanda]

The main difference is that 5s adjust on the inner pad only whist 7s adjust both.

Road calipers work with road levers which pull less cable than v-brakes. Much less common = premium price.

[CAMRAMan]

I've had both and the BB7 is a vastly better beast - much more powerful.

[mrcharly-YHT]

I believe it was rower40 who had multiple instances of BB5 failing under hard braking. Something about a cable pulling past a stop or similar.

Can't find any info online, apart from a mention that the pads are 2/3rds of the size of BB7 pads and hence subject to wearing out very fast. Combined with the single-side adjustment, people are finding they wear out in a single ride (in bad conditions).

[grams]

The main difference is that 5s adjust on the inner pad only whist 7s adjust both.

Is there any functional difference between using the outer pad adjuster and the cable barrel adjuster?

[Kim]

The main difference is that 5s adjust on the inner pad only whist 7s adjust both.

Is there any functional difference between using the outer pad adjuster and the cable barrel adjuster?

It makes the setup easier, as you're only adjusting one parameter at a time, but from experience of other cable discs (Tektro and Shimano) that combine them, it's not actually a problem until either the cables gunk up, or you run out of adjustment

[sizbut]

If you find the BB5's don't keep you happy then consider going to TRP Sprye rather than BB7's.

BB5's were the benchmark for cable operated road disks but that was a good while back. For a heavy rider (me) they tended to need frequent adjusting (after almost every ride) and it wasn't an easy roadside kind of adjust. BB7s made the adjusting a lot easier but it still tended to be frequent. The Sprye's make it super easy (once the pad are properly spaced either side of the disc, you only need the barrel adjuster to cope with pad wear so you're good for the life of the pads).

I also have HyRd and they are in a totally different league in terms of the braking force then can produce and yet still work from cable levers and they automatically adjust for pad wear.

[Brucey]

BB5s work OK and pad life is acceptable if sintered pads are used. Sintered are standard on BB7s AFAICT.  BB7s are a bit easier to live with.

Spyres are a nice (but actually pointless) idea, badly executed. The thrust bearings inside the calipers clap out and the caliper action becomes very poor. In addition the pad adjusters have nothing much to stop them from moving around under their own steam. In the last set I looked at, the disc moved around worse than it would with a BB5 or BB7....

cheers

[Cudzoziemiec]

I've had the opposite problem with one caliper of my Spyres. The titchy teeny 3mm allen bolt that winds the piston in and out rounded off, leaving one pad stuck in virtually the furthest in position. Someone suggested supergluing a sacrificial allen key in to the adjuster but unfortunately it's the spoke side. I've got a replacement caliper and will probably be using the cable adjuster in preference. I've never had any other disc brakes to compare them to but I'm certainly happy with their performance – the power is good but the controllability is the real winner.

[andrew_s]

Is there any functional difference between using the outer pad adjuster and the cable barrel adjuster?

Yes.

If you adjust using the pad adjuster, you've always got the full throw of the caliper lever arm available to move the pad. If you adjust using the cable adjuster, you are using up the lever throw.
After enough cable adjustment, you'll either hit the end stop, or pull the cam over the top, in either case losing braking force.

If the pads adjust both sides, the pads only have to move 2 x the running clearance. If the pad only adjusts one side, the pad has toove the running clearance, plus however much you've worn off the non-adjustable pad. Since the power of the brake is directly related to the ratio between how far the lever moves and how far the pads move, and a single-sided brake caliper has to allow for pad wear, a brake with 2-sided adjustment can be made more powerful than one with single sided adjustment.

Should you be using bar end shifters rather than STI/Ergo, BB7 Mtn plus V-brake levers like the Tektro RL520 are significantly better than BB7 Road and regular drop bar levers.

[Brucey]

I'd agree with the above.   I'd also note that the wear life of the brake pads is not brilliant in BB5 or BB7 calipers in that the brake pads are held off the disc by springs, and the springs sit within the thickness of the friction material. This means that Avid's recommendation is that the pads are replaced after only about one and  bit mm is worn off them (from a friction material  thickness of ~2.4mm) .

If BB5 (road) are set correctly with new pads, and the FPA/barrel adjuster are used as necessary there is enough arm movement such that the pads will each wear about 2mm or so before you run out of arm travel.  However if the brake is not set correctly to start with, or you somehow  manage to wear the pads about twice as much as normal, the arm will run out of travel  in a somewhat abrupt manner; the arm just hits an (invisible) end stop.

So with BB5 road, it is not at all a bad a idea to mark the caliper body with some blobs of paint so that you know if you are about to run out of arm travel or not. I think that BB7 do not have quite the same characteristic.

BTW it could be worse; Tektro managed to make thousands of calipers in which the end of the arm travel was signalled by a 'click' sound as the balls inside the calipers ran off the end of the ramps, leaving you with..... nothing....

cheers

[teethgrinder]

I was going to have new BB7s fitted to my 3 bikes for my year ride. But the mechanic in Trek said that TRP Spyre were even better (and cheaper as well) so I went with those instead.
He was right!
Much easier to align the calipers with a preferably long arm) 3mm allen key. Much less fiddly than using the 25 torque bit and they didn't seize up like my BB7s did (they were still OK, just getting a bit stiffer)

[Brucey]

with BB5 and BB7 the FPA needs to be maintained so that it doesn't seize up(it will corrode in a UK winter...). With any mechanical disc brake caliper it is necessary to strip and overhaul the workings from time to time. With BB5 and BB7 calipers this is easy enough, there are only four (4) ball bearings inside, and normal service is soon resumed.

With spyke/spyre brakes there are about forty tiny ball bearings inside (because they have a needlessly complicated thrust bearing arrangement), no seals of any kind, and normally by the time the caliper is opened up (which is far from easy) it is too late anyway, they are usually f***ed.

cheers

[PaulF]

with BB5 and BB7 the FPA needs to be maintained so that it doesn't seize up(it will corrode in a UK winter...). With any mechanical disc brake caliper it is necessary to strip and overhaul the workings from time to time. With BB5 and BB7 calipers this is easy enough, there are only four (4) ball bearings inside, and normal service is soon resumed.

What's the FPA?

I'm a little slow this morning

[Brucey]

FPA = fixed pad adjuster. BB5 and BB7 use the same design which has a ~24mm x 1mm thread between two aluminium parts; add salty water and the parts will seize. Use copper ease  (sparingly) on the screw threads. Once a year is enough.

cheers

[PaulF]

FPA = fixed pad adjuster. BB5 and BB7 use the same design which has a ~24mm x 1mm thread between two aluminium parts; add salty water and the parts will seize. Use copper ease  (sparingly) on the screw threads. Once a year is enough.

cheers

Thanks! Looks like my weekend is planned then

[Brucey]

while you  are at it, it isn't a bad idea to clean and lubricate the actuation mechanism in the left side of a BB5/7 caliper. Use a moly grease, ideally a ~50% moly assy paste. This needs doing about once every two years or so.

It is also a good scheme (eg for a commuting bike) to have a third (spare) caliper ready to go so that you simply swap calipers when one is due for overhaul.

cheers

[sizbut]

I've heard of the Sprye adjuster issue undoing itself issue - all I can say is I've heard of it but never encountered it, ie. its certainly not universal but as is the way with all forums people rarely post opinion about something not happening.

However, the ease of adjust for pad wear makes the BB5/BB7's designs look silly (they can be forgiven for being an much earlier design but its odd that Avid haven't seriously addressed that issue).

[Dtcman]

Thanks for the thoughts and comments.

I must admit I was unaware of the Sprye and that does seem the way to go if the BB5's turn out to be cr@p.   

[Brucey]

However, the ease of adjust for pad wear makes the BB5/BB7's designs look silly...

disagree; it is not complicated or difficult, and (unlike the spyres) the adjusters are properly engineered with detents etc.  All the spyres have is a smear of blue Loctite on the adjuster threads. This stops working after just a few adjustments, which is why the adjusters work loose so often.

cheers

[ElyDave]

I've had BB7 Roads for about 2 years and find the adjustment mechanism one of the easiest things about them.  It was a bit tricky to get the initial set up right in terms of cable tension, but once done no need to adjust it so far.  I imagine I would find it easier next time around though as I now have the 3rd hand tool to help.

Stopping power so far is excellent, bring a recumbent to a stop downhill pretty decently, even enough to lock up the back once or twice when coming to a halt.

That bike will be going off the road for a bit of work later in the year, so it will also be the point to check pad wear.

[Bolt]

Although I'm embarrassed to admit it I bought and fitted a pair of fake BB5s (5 quid including postage and rotors ) to my 38lb lump of a commuter bike.  They've proven to be consistently effective and easy to maintain over 2 years of everyday commuting and although I can see that the BB7s are a more refined design I wouldn't choose to upgrade from BB5s on a new bike. If there was spare money to be spent I'd be looking at a saddle or tyre upgrade... perhaps.

My conscience and sense of self preservation did get the better of me and I bought a pair of genuine BB5s to replace the fakes that I thought would only last 6 months but they are still in the spares box