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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 03-13-14, 07:45 PM   #1
twocicle
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got a mothballed Gates CDC rings & belt?

I did a same-side drive belt setup using the CDX (CenterTrack) rings & belt, which is working great (as reported in another thread). Always the curious George, now I'm curious about how the CDC setup would compare.

If anyone has a set of the 'ol mudports they never plan to use again and would like to donate them to the cause, please PM me. 69T rings only.

Thanks.
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Old 03-14-14, 03:18 AM   #2
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I had setup our CDC rings as a single-side drive, with the belt rings in the outer position of 5603 triple cranks, flipped so that the flat side was against the crank spider and the open side faced outwards. There wasn't QUITE enough space behind the right crankarms for the belt rings to fit without being slightly distorted (pushed towards the inside by the crank), so I filed off 1 or 2 mm from the ring behind the crank to get the clearance needed. The belt wasn't running on this section, so I hoped it would be OK. In the end, the belt did rub a little on the back of the crank arm, and you can see where it lightly polished it, but no worse than many people do with their heels on the outside of cranks. This was with the 71 tooth belt rings, since the 69 tooth rings have a smaller radius, the cranks would be even closer to the ring with that size, thereby marginally increasing the problem.

This was my main motivation for switching to the CDX belt and rings because that setup is slightly narrower, and it's also possible to control the lateral position of the belt-ring a little because the bolt holes are laterally in the center of the ring rather than on the edge. With this setup, we have no belt / crank interference issues. As I've mentioned in other threads, anyone wanting to do this themselves should try to get the 5603 105 cranks not the newer 5703 because the 5603 has slightly more room behind the crank.

I therefore have a set of 71 tooth rings and belt that have about 10,000 kms on them, aren't showing any signs of wear, but have had some minor filing done to the rings. The 71 tooth rings JUST allow installation on a stock Co-Motion Speedster, but the fit is very tight even with the eccentric in it's most rearward position. In fact, that was the second motivation to get the CDX rings, so that I could increase the captain's saddle setback by moving the eccentric BB forward instead of moving the seat closer to the stoker, and also get the saddle closer to the ground while maintaining the same pedal to crank distance.
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Old 03-14-14, 12:12 PM   #3
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The 71T would not work for me either due to its required eccentric position (as with your stated case).

With my current CDX (CenterTrack) same-side test setup (standard triple FSA SL-K Light cranks + 3.5mm spacer + CDX) there is still plenty of room between that and the crank arms, so I'm pretty sure a wider 69T CDC ring would work without any issue.

Last edited by twocicle; 03-15-14 at 02:15 PM.
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Old 03-19-14, 02:07 PM   #4
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Due you have any pictures of your set up. Im thinking of switching over due to worn timing chain and rings. I guess know would be the best time.
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Old 03-19-14, 02:13 PM   #5
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Quote:
Originally Posted by twocicle View Post
I did a same-side drive belt setup using the CDX (CenterTrack) rings & belt, which is working great (as reported in another thread). Always the curious George, now I'm curious about how the CDC setup would compare.

If anyone has a set of the 'ol mudports they never plan to use again and would like to donate them to the cause, please PM me. 69T rings only.

Thanks.
The CDX, is a major design improvement over the CDC. The belt/ring engagement is significantly better. I would not even consider the CDC.
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Old 03-19-14, 04:47 PM   #6
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The CDX, is a major design improvement over the CDC. The belt/ring engagement is significantly better. I would not even consider the CDC.
Agree about the CDX, but I have very little experience with the CDC (and why I am curious to do a direct compare). Gates tech support also says the CDX is working out very well and that CDC (Mudport) components will be discontinued (no date mentioned). I had phoned them to ask about CDX ring offsets (found an error in their docs) and how I thought having a built-in offset helped rather than hindered installation options. Gates' objectives at this point is to reduce production costs, so we probably won't see any new tandem options for a while.

Last edited by twocicle; 03-19-14 at 04:51 PM.
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Old 05-20-14, 10:42 AM   #7
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Not a tandem, I have a Civilian Rebel with the old CDC/Mudport. Between torn right meniscus and some other issues, <30 miles on it so far. Started shopping for a 46/130 but so far not to be found . . . it looks like my only option is to replace the whole system. About 1/3 - 1/4 cost of the bike excluding any required shims . . .

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