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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 09-18-07, 01:03 PM   #1
RickinFl
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Magura HS-11 to disk conversion?

I've had the Magura road model of their hydraulic caliper style brake on my Cannondale tandem for many years now and have really enjoyed them. I think the road version was called the HS-11, but I'm not sure.

I'd eventually like to go to disk brakes, and since I'm a confirmed bar-end shifter guy, it occurred to me that I might be able to keep the the road levers and hook them up to hydraulic cylinders rather than going with the cable actuated brakes as seems to be common on road tandems that are equipped with disks.

Anyone know if those road levers will push enough fluid to work with the disk cylinders?

Thanks-

Rick
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Old 09-18-07, 02:43 PM   #2
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Originally Posted by RickinFl View Post
I've had the Magura road model of their hydraulic caliper style brake on my Cannondale tandem for many years now and have really enjoyed them. I think the road version was called the HS-11, but I'm not sure.
If the brake came with road style levers, it's AFAIK either the HS-66 or the HS-77.
Further, AFAIK the levers and calipers of the rim brakes are compatible only with other rim brakes. E.g. HS-33 with HS-66.
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Anyone know if those road levers will push enough fluid to work with the disk cylinders?
I found this on Magura's forum (under magura.com > service > forum)
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Originally Posted by Martin Schäfer Head of marketing @MAGURA Germany
MAGURA not only advises against ANY trial and error tests in that context but even WARNS to do it.

A disc brake that is actuated with a HS 33 master becomes a closed system WITHOUT the absolutely necessary expansion chamber (reservoir). Result: a blocked brake all of a sudden with potential serious consequences for the user.
To make it short: let it be if your health is important to you...
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Old 09-18-07, 03:21 PM   #3
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Thanks to Rincewind8 for the info. It sounds pretty unequivocal. Seemed like a good idea at the time.

This is a great forum, and I really appreciate those who take the time and effort to share their expertise!

Rick
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Old 09-18-07, 10:53 PM   #4
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Not being a disk brake user, I have no personal info to share. That being said, from what I've read, *good* cable operated disks (IE: Avid BB7s) work pretty darn well. Sure you have to use the barrel adjuster as the pad wears, and have to take care of the brake cables (keep 'em clean), but those don't sound like deal breakers to me.

Oh, additional reading. A couple years old, but very informative: Cantilevers vs. V-brakes vs. Disc
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Old 09-19-07, 10:28 AM   #5
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That being said, from what I've read, *good* cable operated disks (IE: Avid BB7s) work pretty darn well. Sure you have to use the barrel adjuster as the pad wears, and have to take care of the brake cables (keep 'em clean), but those don't sound like deal breakers to me.
Actually, the Avid BB7s have dial knobs for brake pad adjustment for both sides. You don't have to use the barrel adjuster.
And yes, they work great. IIRC they performed better than several hydraulic disc brakes in some test that I read about. (sorry, don't have the link right now...)
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Old 09-19-07, 08:30 PM   #6
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We're not lightweights, and our MTB tandem is porky compared to a road tandem, but the Avid brakes do a fine job of stopping us.
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Old 09-20-07, 02:26 PM   #7
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My aversion to cable operated disks is the same as why I don't like V-brakes on road machines- V-brakes and mechanical disks are designed to work properly with MTB style levers only. Road levers don't pull enough cable- you can test it yourself. MTB levers pull almost exactly twice as much cable as a road lever.

To make V's and mechanical disks work with road levers (read that as "STI" shifters"), you have to resort to devices like Travel Agents and so forth which work by trading mechanical advantage for length of cable moved. So you take nice strong brakes that work fine in their intended setting and force them to work with road levers by effectively making them weaker. Totally bogus in my opinion, and a triumph of marketing over reason and the creation of a need where none previously existed. Hah! I'm enjoying this rant so much that I forgot what my original point was.....

And, to add insult to injury, you've got that long run of stretchy cable going to the brake brake, meaning it hardly works to begin with, then you put something on it that makes it work even worse. That makes sense.

I'm really an advocate of hydraulic brakes for road tandems, and I agree with Christophe Timm that the Magura HS-66 system is probably the best brake system that you can put on a road tandem. Unfortunately, they preclude the use of STI, which makes them out of the question for most people.

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Old 09-20-07, 02:41 PM   #8
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No problems with our mechanical rear brake. But we obviously have the correct levers.
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Old 09-20-07, 03:19 PM   #9
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My aversion to cable operated disks is the same as why I don't like V-brakes on road machines- V-brakes and mechanical disks are designed to work properly with MTB style levers only. Road levers don't pull enough cable- you can test it yourself. MTB levers pull almost exactly twice as much cable as a road lever.
There is a road version of the Avid BB7 available that works wonderfully without any travel agent. I use one of those on the front of our (road) tandem and it works great. Unfortunately our tandem doesn't have rear disc tabs otherwise I'd have a BB7 (road) on the rear as well.
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Old 09-20-07, 03:20 PM   #10
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Brian-

My point exactly- you have the MTB lever that's designed to work correctly with whatever type of mechanical rear brake you have on your mtb tandem.

Rick
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Old 09-20-07, 03:28 PM   #11
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Thanks again Rincewind8-

I was unaware that there is a road version of the Avid disc. Last time I checked new road tandems (a couple of years ago), I wanted to go with discs, and the dealer I was working with warned me that the (mechanical) disks didn't work all that well, and that he was installing Travel Agents on any road machines he sold that had disks. He also said they didn't work all that well even with the TA's. Glad to see there's been advances.

I'm still a fan of hydraulics, mainly because they are essentially lossless, and it makes a big difference on that long run to the back brake. I'd sure like to see someone make true hydraulic road disk.

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