BB7 Road vs MTB

I’ve installed some BB7 MTB callipers with Tektro RL520 levers. I’ll preface this by saying I’ve never used disc brakes before, so my expectations may be mismatched.

The levers need pulling further back than I would expect before the pads start contacting the disc. Even with the levers pulled all the way back, the braking force feels weak.

I’ve since seen that BB7s come in a Road version. The RL520 I believe are long pull and should work well with the BB7 MTB.

Should I just tinker with the pad adjusters, or have I got the wrong callipers? Will BB7 Road versions work better, just the same, or not at all with the RL520?

Thank you!

the resident expert is @edscoble

How close are the pads to the rotor? With BB7s they need to be just not touching. One pad at a time, I start with the more awkward inner one, wind the pad adjuster in while spinning the wheel until the pad rubs, then rotate it back one notch. Do the same for the other pad. Pull the lever hard and check again for rubbing. Sometimes I have to put up with some rubbing to achieve satisfactory braking.

Also worth making sure your cable outers are terminated nice and square with a file or grinder to minimise losses

The combination you have should work together. I'd start by getting the pads as close to the rotor as you can without them rubbing (make sure your rotor is straight) before you even clamp the cable in. Then clamp the cable tight, I don't think BB7s have barrel adjusters so you will have to get it as tight as you can by hand.
You could even clamp the pads down on the rotor then use the bedding/stretching of the cable to give you some clearance by pulling the lever as hard as you can.

Just did the same thing @timmbo
Initially very disappointing.

I bought new pads, (they took longer than I expected to bed in). Also used compression less outers.

And I followed the second video instructions on this page

https://www.cyclechat.net/threads/setting-up-avid-bb7-road-disc-brakes.124882/

Levers still pull back a lot but I like that, no rubbing, brakes are pretty good.

Good luck

You could even clamp the pads down on the rotor then use the bedding/stretching of the cable to give you some clearance by pulling the lever as hard as you can.

In my experience with BB7s this would make the braking force worse. The lever arm on the caliper only has so much travel before the length of the lever arm is reduced, thus reducing braking power. This is the fundamental problem with BB5s where using a cable length adjuster to adjust for pad wear ends up reducing mechanical advantage at the brake.

With BB7s I just pull the cable tight, with the lever arm in the fully rested position and clamp the cable. I never touch this again, you want the full leverage throughout the brake lever travel. Then adjust pads.

With BB7s I just pull the cable tight, with the lever arm in the fully rested position and clamp the cable.

This.

If there’s too much movement, then the non moving pads is too far from the rotor and need to be adjusted closer, like very barely touching the rotor.

If it’s already close to the rotor, turn the moving pads as close as you can.

The power won’t come straightaway, it take a dozens of ride for it to bed in nicely and it will squeal until it die down.

1 Attachment

This is the fundamental problem with BB5s where using a cable length adjuster to adjust for pad wear ends up reducing mechanical advantage at the brake.

TBF it was just to take up the cable slack, BB5 advantage is that the body is one piece and stiffer.

th Tektro RL520 levers

Check if it’s actually V brake pull, e.g. RL-340.

The ‘clamp the cable with the arm fully rested’ sounds good but, ime, leads to a little bit of free lever travel before the arm actually moves. I always end up pretensioning it a bit.

Thanks everyone for offering their advice. This video was incredibly helpful - I think the pretensioning of the lever when clamping down the cable was particularly helpful.

Saved me £100 trying the Road callipers!

Yeah just need to tighten it until the lever doesn't have a play.

http://howtosetuptheavidbb7.weebly.com/how-to-set-up-the-avid-bb7.html

That is the bible or BB7 setup. In the last four or so years of BB7s on my tourer/daily ride, never had a single issue following this setup.

Long live the BB7.