Avid BB7 tinkering

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  • Avid BB7 tinkering
  • IHN
    Member

    Isn’t the difference the length of the arm? You can take the arms off, I know this through ‘happy’ accident…

    Premier Icon cp
    Subscriber

    As above, it’s the arms that are a different length.

    billytinkle
    Member

    Web searches have conflicting answers to the above. I can’t be bothered to get the tape measure out just yet, but going from the two images below I’d say that the arms are the same length, but have different resting positions.

    billytinkle
    Member

    Definitely the same length arms using those images:

    billytinkle
    Member

    From what I’ve read the difference between the road and MTB Avid BB7 callipers is the internal cam that allows for use of different pull brake levers.

    I have both types, but don’t particularly like the platinum colour on my CX bike. So can I swap the cams over? Difficult job?

    billytinkle
    Member

    Early riser bump

    cynic-al
    Member

    given the above the cam must be different.

    Fisher outdoor, the importer, lists & sells spares with exploded diagrams that may help.

    Premier Icon cp
    Subscriber

    Interesting – looks like things have changed. I’m sure the mtb lever arm used to be longer than it is now.

    I run BB7 road calipers with MTB levers on my tandem and it works just fine – not sure if this info is of use to you!

    billytinkle
    Member

    Thanks for the tip on the exploded diagrams from fisher. All I need to do now is work out which bits need swapping over!

    unovolo
    Member

    No expert on these but I’d imagine the arm and associated cam are just assembled in a slightly different position at the factory to account for cable pull before the pads engage.

    The bodies and arm length appear the same just painted a different colour and originally there was only a MTB version which I’m sure for a long time would be the one used on road/cyclocross builds prior to a specific ‘Road’ labelled version being made available.

    Tektro,Hayes etc until recently only seemed to have a Cable operated disc brake available that were just that and not specifically labelled for Road or MTB use and yet have been used on MTB’s,Cross bikes,Utility bikes…..

    Premier Icon Del
    Subscriber

    No expert on these but I’d imagine the arm and associated cam are just assembled in a slightly different position at the factory to account for cable pull before the pads engage.

    hmm. i’m not so sure about that. if there’s less travel on the cable, and therefore the ( caliper ) lever, surely you’d steepen the pitch on the cam to achieve the same movement on the piston?
    adjusting the lever location would accommodate a change in mechanical advantage of the lever but that’s all it would do. i think. ❓

    billytinkle
    Member

    Well, the MTB calliper came apart without too many issues. I think the cam must be the silver bit with the ball bearings on it. Only when I get the road version apart will I be sure.

    It’s a job I’m going to leave until the weekend as it’s on my commuter and the road callipers are on it.

    unovolo
    Member

    Well if that is the cam above really cannot see what would be different in the road version,surely if the cam was a different length then the caliper body would need to be different to accommodate it?

    I stand to be corrected though 🙂

    billytinkle
    Member

    There are grooves which vary in depth on both the cam and the body. The bearings sit in these groves and determine the travel of the cam when it rotates.

    I’m thinking the groove depth will be different on the road version, but there’s only one way to find out!

    markenduro
    Member

    Groove angle on the cams/ramps is steeper on the road ones to move further out for the same amount of lever arm travel. The cam/ramp is the black part in the calliper body and the corresponding part with the adjusters and balls on it in your photo.

    clubber
    Member

    I’ve always wondered what they looked like inside but never had reason to take them apart. thanks 🙂

    coastkid
    Member

    I have BB7 road calipers on MTB levers on a Karate Monkey, they are an amazing brake set up compared to my other 3 sets of MTB BB7 Avids.
    No idea what the differance is TBH! :D.
    You also get cable adjusters with the road set. I did have these road BB7s on a Fargo before with Sora drop levers. They were good on that but way better with the MTB levers.

    No idea what it is thats differant but they are way more progressive than the MTB calipers 🙂

    The Sram website has a pdf on stripping them to service; Sram BB7 pdf

    unovolo
    Member

    Groove angle on the cams/ramps is steeper on the road ones to move further out for the same amount of lever arm travel

    That makes sense ,looking purely at the silver part was difficult to see how it could be different but the ramps on the grey/black bit being different between road & mtb makes more sense.

    Still begs the question why a lot of the other manufacturers only produce brakes which dont seem to specify if it is for Road or Mtb use.

    billytinkle
    Member

    The Sram .pdf would have been helpful last night! Glad you’ve posted it though – I was wondering whether the fixed cam was actually fixed or whether there was some way of getting it out.

    I’m now wondering whether the fixed cam on the calliper body will be different between the two models as well as the rotating cam. If it is there won’t be any point in swapping the rotating cams around.

    In fact it might just be easier to paint the road callipers now I know how to take them apart!

    cynic-al
    Member

    I can’t see why it would be different.

    As for mixing road and brake calipers/levers, it would be similar to v-brakes and cantis….adn we know how well that works, right? 😛

    My gripe of the week, a customer had a seized BB7 replaced in our shop, he took it home and I later offered him £10 for it…idiot had THROWN IT OUT 😡

    what is it with people these days, is everything disposable?

    boblo
    Member

    Surely if it was repairable, you should have repaired it instead of replacing and then making some dodgy unsolicited offer…. That would raise my suspicions and could bring your employer into disrepute. I’d be careful if I were you…

    Premier Icon Davesport
    Subscriber

    Surely if it was repairable, you should have repaired it instead of replacing and then making some dodgy unsolicited offer….

    Typical STW statement.

    Boblo, I don’t know how much you charge your labour out at, but repairing stuff like this in some cases simply doesn’t make economic sense. Better for both parties to use a new part. The offer to buy the defective part back ! What’s wrong with that ? It has residual value.

    An analogy would be your car being written off because it’s uneconomical to repair. There may be little preventing it being put back into use & the “write off” is sold to someone with the time & skills to put it right again.

    That would raise my suspicions and could bring your employer into disrepute. I’d be careful if I were you…

    Whatever….yawn..

    boblo
    Member

    Yep, double yawn. Typical STW response to querying practices that could look dodgy….

    clubber
    Member

    Triple yawn. Stop fighting over silly things on such a lovely day 🙂

    cynic-al
    Member

    boblo – Member
    Surely if it was repairable, you should have repaired it instead of replacing and then making some dodgy unsolicited offer…. That would raise my suspicions and could bring your employer into disrepute. I’d be careful if I were you…

    Quadruple yawn.

    Of course we offered to repair it, it was uneconomic – about the same price as a new caliper, and we’d have had to buy a tool to guarantee a proper job.

    Have you heard of “reduce, re-use, recycle”?

    boblo
    Member

    So why did you want it for £10 if it was uneconomical to repair?

    Just to be clear, I’m not suggesting you were trying it on just that the impression could be formed so apologies if that’s what has come across.

    Stretch+yawn aaand turn over.

    cynic-al
    Member

    boblo – Member
    So why did you want it for £10 if it was uneconomical to repair?

    Just to be clear, I’m not suggesting you were trying it on just that the impression could be formed so apologies if that’s what has come across.

    Stretch+yawn aaand turn over.

    Because it had residual value (see above) – I could have repaired it for £18 odd and used it or. sold it for a profit.

    I don’t see how this is or could even be interpreted as “trying it on”.

    boblo
    Member

    OK, so £18 to repair and what, £40 for a new one? How is that uneconomic to repair? I suspect you’ve left out the labour in your number.

    clubber
    Member

    Of course he has. He wouldn’t charge himself labour…

    walleater
    Member

    LOOOOOOOOOOOOOOOOOOOOOOOOOL!

Viewing 31 posts - 1 through 31 (of 31 total)

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