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Pretty much given up on ETAP Red, now considering 10speed Hydraulic.

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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!

Pretty much given up on ETAP Red, now considering 10speed Hydraulic.

Old 10-25-20, 12:56 PM
  #51  
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Agreed and it is more important than ever with smaller rings given the greater wear from increased chain tension and fewer teeth sharing the load.
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Old 11-08-20, 04:37 PM
  #52  
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Originally Posted by Alcanbrad View Post
the problem showed at the very first ride. We have put about 500 miles over 20 rides on the bike since the conversion and it has been a constant issue. I am confident the chain and chain ring are not worn, but now I lack confidence in the chain and chainring.

i have a new 32 tooth Sugino ring and a new KMC X11 chain in hand and will try that.

in terms of excess torque or torque margin, would there be greater torque on a 34 front, with 35 rear, than a 30 front with 32 rear all other things being equal (team weight, speed, climbing speed)? Are there equations to calculate effective torque? I did a simple spread sheet a while ago and if I finoogled it right, there would be greater torque on the smaller of the rings And greater tension in the chain, all else equal.
Your torque will always be higher with a smaller chain ring. It's simply due to the fact that the smaller the ring, the longer the effective leverage arm the crank becomes. Rear cog has no bearing on chain loads at the chainring. But the rear cog DOES affect how much torque is being applied to the cassette, freehub body and hubshell. Larger cogs effectively being longer lever arms as well.
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Old 11-08-20, 04:42 PM
  #53  
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Originally Posted by Alcanbrad View Post
We were finally able to get out for the first ride on the new chainring and chain and did the same climb that I captured in the video above. The verdict: No chain skip!!!! In addition to the new 36 T Chain ring from Precision Tandems, and a new KMC X11 chain, I also changed the cassette from the Shimano 11-40 to the SRAM 11-42 (to compensate on the low end for the larger chainring) and I put the Digirit Large cage back on since I had eliminated it as a contributor.

For grins, I measured the depth of the gullets on the problematic 34T and the new 36T chain rings and the 36T gullets were noticeably deeper. Perhaps the 34T ring was shy on tolerances, or the tips of the teeth were worn down. I suspect the former over the latter.

I am feeling pretty good about it, my stoker, on the other hand said only "I still don't trust it". So it's going to be a while to regain confidence, but I think I got it, finally. I'll circle back in another 500 miles or so with an update.

This was a tricky one. It was taking the effort to set up a camera to "see" what was actually going on to know for sure.

Thanks for all the input and suggestions folks.
Yeah! So glad to hear the culprit has been identified and the problem solved!

The only thing I could add is suggesting you opt for a stainless steel chainring instead of aluminum. It will last far longer and not suffer chain skip nearly as soon. This should give your stoker additional confidence in your drive train. I'd also say that there are a LOT of monster tandem teams in the world who put ungodly amounts of power to the pedals, and they can do so without skipping, chains disintegrating and hubs exploding. So hopefully your stoker can be comforted by this fact. (Unless, of course, that you and your stoker happen to be current or former national tandem sprint or TT champions! Then all bets are off!)
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Old 11-09-20, 08:27 AM
  #54  
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Originally Posted by LV2TNDM View Post
Yeah! So glad to hear the culprit has been identified and the problem solved!

.... So hopefully your stoker can be comforted by this fact. (Unless, of course, that you and your stoker happen to be current or former national tandem sprint or TT champions! Then all bets are off!)
We are nowhere near any national, regional, local, (or even just us) in terms of team performance. But we do have a history. I couldn't find pictures of the teeth we have sheared off a few late 20th century freewheels, or the few chainring teeth we have bent, but I offer these in support of my claim:

We did this on 2 separate wheels (Though I suspect this happened during hard braking while descending, but as you know, my self diagnosis record is not great):



We did this to 3 different cassettes:

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Old 11-11-20, 01:56 AM
  #55  
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Nice job shearing the cassette spider! I'm impressed! Now, not to minimize the awesomeness of snapping your "flanges," but those spoke end beds seem REALLY flimsy if you ask me.
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