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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 05-08-08, 01:22 PM   #1
adamlaw
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Join Date: Apr 2006
Location: Ithaca, NY
Bikes: 1980 Mercian Olympic, 2004 Spectrum Ti custom, 2007 Bob Brown fully lugged steel tandem with S and S coupling and DaVinci ICS
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Tandem rear disk brake/QR problem

I have a Bob Brown lugged steel tandem. I have been taking my 10 year old daughter out for rides. Initially after around 100 yards the resistance to cycling would increase and the BB7 disk brake would be slowing down the disk despite not activating the brake. After some messing around I concluded the exposed QR skewer was just not tight enough despite using the 90 degree rule. I purchased a Bob enclosed tandem QR skewer. With this I have been able to go on 20 mile bike rides. However, by the end of the ride on occasion the same problem occurs. Maybe I was just slight short of the 90 degree rule for tightening the QR skewer. I have since read some of the literature on standard forks and disk brakes. I was wondering if the torque of the disk brake is just causing the wheel to go out of alignment sufficiently to make the BB7 disk brake out of true and hence add friction. Unwinding the BB outer adjustment does improve the situation - as does releasing and then retightening the QR skewer. Any thoughts of a more robust solution? Should I go beyond the 90 degree tightening rule so the QR is biting even harder?
I didn't use disk brakes for the front!

Technical information

Drop outs - comments from Bob Brown "I also chose to use Henry James Dropouts on this one, which is a departure for me. I typically don't care for them much, but they really fit this application well. The tandem chainstays are larger diameter than most, so the large touring dropouts fit the diameters really well. Most forged dropouts tend to look a little small in these larger stays"

Wheels: Velocity 36 rims
Hubs: Chris King
Davinci Drive
145 mm spacing
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File Type: jpg rear drop out.jpg (35.3 KB, 38 views)
File Type: jpg rear disk brake medium.jpg (81.5 KB, 42 views)
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Old 05-08-08, 03:04 PM   #2
dfcas
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I recently had a similar problem on the front of my mtb. The bottom line was as follows:

The cartridge bearing hub had a bad bearing-it was totally seized. It would spin on the axle during normal riding with only slight drag, but upon brake application it would bind at the axle, causing the wheel to move in the dropout. I put a heavy skewer on first, but after 2 trips over the bars I got the idea something was wrong.

So, I suggest you check out the bearings and make sure they are smooth.


dan
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