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Tandem Cycling A bicycle built for two. Want to find out more about this wonderful world of tandems? Check out this forum to talk with other tandem enthusiasts. Captains and stokers welcome!

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Old 08-05-12, 09:39 AM   #1
Tandem Tom
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Disc Brakes & Barrel Adjusters?

Our Co-Motion Speedster,1 year old, did not come with adjuster on the brakes. Is it something that is worthwhile adding? I plan to add the "helper spring".
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Old 08-05-12, 11:11 PM   #2
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Instead of an inline adjuster, you should use the pad adjustment dials on the inside and outside of the BB7 disc brakes (assuming that is the model that you have). Avid specifically recommend using the adjustment knob rather than using an inline barrel adjuster because using a barrel adjuster would change the angle of the braking arm where the cable is clamped.
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Old 08-06-12, 04:58 AM   #3
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The in-line barrel adjuster is a good idea under two caveats:

1. Best suited for heavy rear-brake users, it should to be installed where it can be reached safely while riding, e.g., just ahead of the cable stop on the down or top tube
2. It should only be used to make 'on the fly' adjustments during rides where heavy disc use has cause brake-level pull to become marginally effective.

As noted by Chris, to maintain the optimum amount of clearance between your rotor and brake pads -- which reduces the likelyhood of brake rotor rub from normal amounts of rotor runout -- you should back-off on the barrel adjuster once you reach the end of your ride and verify that you still have plenty of brake pad material left. At that point, the original or new brake pads should be adjusted with the brake arm in the nearly full-opened position (I like to put a little extra pre-load on the brake cable, which you can do with the in-line adjuster) and then re-set the brake pads using the built-in caliper adjusting knobs per Avid's instructions.

If you're not a heavy rear-brake user, then you'll rarely need to mess with your Avid BB7 so it doesn't matter.
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Old 08-06-12, 08:37 AM   #4
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^^^ Actually, Avid provides a good barrel adjuster with the BB7 bundle and you can use this for your inline needs. The caveat Avid makes is to only use the barrel adjuster to take up cable slack and not where it begins to actuate the brake caliper arm.

The barrel adjuster Avid provides is a great way to fine tune the point where the caliper actuation begins - otherwise you are stuck with using only the cable fixing bolt on the caliper itself.
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Old 08-07-12, 03:47 PM   #5
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Thanks for the replies! I am not going to have time to add the adjuster before we leave for a trip. I will work at keeping the pas abit closer to the rotors.
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Old 08-07-12, 04:11 PM   #6
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...you should back-off on the barrel adjuster once you reach the end of your ride and verify that you still have plenty of brake pad material left.
This is a visual inspection, looking down? What are the criteria for plenty of pad material?
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Old 08-07-12, 07:01 PM   #7
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This is a visual inspection, looking down? What are the criteria for plenty of pad material?
At least 1/2 the thickness of the metal backing plate and you're golden.

The backing plates are 2mm thick and so are the pads when they're new. The recommended replacement point is a 50% loss of brake pad material. If someone wanted to do a "relative measurement" of the pad, most multi-tools have a 2mm allen / hex head wrench that you can put up against the pad material to see how much material is left.

Now, if you're pretty good about keeping track of your brake pad wear and keeping your brake adjusted you can probably get away with taking the pads down to .5mm or less, but at some point you're going to end up with metal on your rotor, and that ain't good.
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Old 08-07-12, 10:54 PM   #8
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While on topic of the Avid BB7, I definitely recommend the Shimano XT RT86 IceTech 6-bolt Rotor as a performance upgrade/replacement for any of the Avid rotors. I installed the IceTech 203mm a couple months ago and this rotor performs great even with the default (original) Avid pads. Solid braking, no squeeling, no warping, and very little rotor heat which I'm pretty sure will extend the pad life.
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Old 08-08-12, 06:48 AM   #9
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You mention the rotor upgrade and now that has me asking another newbie question.
How to I determine when it is time to change the rotors?
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Old 08-08-12, 09:07 AM   #10
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You mention the rotor upgrade and now that has me asking another newbie question.
How to I determine when it is time to change the rotors?
Solid steel rotors seldom wear out on road bikes - at least for the typical usage from most of us. Otherwise, consider changing it when it is warped, or gives an embarrasing squeel you can no longer tollerate, or you just have an itch

The IceTech rotor has 2 steel brake surfaces sandwiching an aluminum core, which is part of the reason it doesn't heat up like the solid steel Avid rotors. As a design trade-off, the IceTech layers (at least in theory) could separate or you could potentially melt the AL core (reports from a German torture test lab) though I have not found a posting of anyone IRL actually accomplishing that. Ours is working great and I'm pretty light on using brakes so not worried.
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Old 08-10-12, 07:19 AM   #11
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We descended Mt Ventoux (toward Malaucene) this summer with a new IceTech rotor in our older BB7 drag brake. Used it heavily on the upper, steeper, sections in part because of very strong winds that made handling the bike dicey. No problems. No fade. Very confidence inspiring.
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Old 08-10-12, 04:31 PM   #12
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We descended Mt Ventoux (toward Malaucene) this summer with a new IceTech rotor in our older BB7 drag brake. Used it heavily on the upper, steeper, sections in part because of very strong winds that made handling the bike dicey. No problems. No fade. Very confidence inspiring.

Cool! (excuse the pun). Really though, using a disc as a drag has to be even heavier usage than a on/off main brake.
1) Any idea how hot the IceTech got?
2) What pads?
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Old 08-10-12, 06:57 PM   #13
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1) Any idea how hot the IceTech got?
No (I don't touch hot discs). But we had no fade that we could perceive (stoker runs the drag brake, but I'm paying attention, too.)
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2) What pads?
Ack. Tried to find the purchase records, but alas... They are the Avid sintered metal, but can't find the actual ID/model #. Sorry.
UPDATE: Found it, just need to get better at this whole intertubes thing: here is a link to the pads I installed in prep for the Provence trip:
http://www.amazon.com/gp/product/B00...ls_o03_s00_i00

Last edited by 2frmMI; 08-10-12 at 07:07 PM. Reason: Found it.
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Old 08-11-12, 09:05 PM   #14
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No (I don't touch hot discs). But we had no fade that we could perceive (stoker runs the drag brake, but I'm paying attention, too.)

Ack. Tried to find the purchase records, but alas... They are the Avid sintered metal, but can't find the actual ID/model #. Sorry.
UPDATE: Found it, just need to get better at this whole intertubes thing: here is a link to the pads I installed in prep for the Provence trip:
http://www.amazon.com/gp/product/B00...ls_o03_s00_i00

Great, thanks for the update. Good to hear the sintered worked so well. I have a set of sintered pads waiting in the wings - "EBC Disk Brake Pads for Avid Mechanical-Gold" which were recommended by somebody on the Avid disc brake thread (under Tandem Cycling).

Yeah, don't touch a rotor with fingers/skin - ever, just flick a little water on it to see if it sizzles. Don't douse it with water else it could warp.
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