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Gates Carbon Drive timing belt eating bottom brackets?

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Gates Carbon Drive timing belt eating bottom brackets?

Old 07-26-21, 06:02 PM
  #26  
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Sram bb

Yes, come to find out my BB or reversed. The stokers is common and the captains is opposite. The SRAM BB that I need is discontinued. My bike mechanic suggest flipping the eccentric over 180 degrees and then the SRAM BBís will be the same. Can that be done? Are eccentric BB reversible?

Thanks in advance!

Dave
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Old 07-26-21, 09:07 PM
  #27  
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Originally Posted by Alcanbrad
After all the comments and trying with the belt tension looser, I believe that in addition to having excessive runout, I have been running the belt way too tight which is likely my problem (I never could get a consistent tone out of the belt strumming method). To set the looser tension I choose the limit to be just a bit tighter than the belt being able to climb out of the center track when slowly turning the crank and pushing the belt sideways just ahead of where the belt met the ring. If the belt climbed out of the center track and started to ride on top of the ring, I backed off and adjusted the eccentric just a bit tighter. Riding it over the weekend it performed well, but I still need to replace the BB (or bearings) as these are ruined. I believe the belt tension measures in the low 30lb range and the difference due to runout is fairly small.

I'd be curious of how others determine "loose" as "loose enough" or "too loose".
I bought my first Gates timing kit from https://www.precisiontandems.com. His advice was tension just enough to hear a tone when you pluck the belt.
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Old 07-27-21, 05:18 AM
  #28  
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Originally Posted by jays35
Yes, come to find out my BB or reversed. The stokers is common and the captains is opposite. The SRAM BB that I need is discontinued. My bike mechanic suggest flipping the eccentric over 180 degrees and then the SRAM BBís will be the same. Can that be done? Are eccentric BB reversible?

Thanks in advance!

Dave
Are you talking about using the tandem specific BB for the stoker? If so, I think you could flip the eccentric around, however, BBís (and pedals) are threaded the way they are to prevent the cups natural tendency to unscrew. You will have to stay on top of it to make sure it does not self loosen on you.
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Old 05-09-23, 09:50 AM
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Excellent analysis. Appreciate the comments and your thoroughness. Are you sure the click click is coming from from your bottom bracket. I occasionally get a ticking noise which is caused by the belt. Spray my belt with silicon eliminates the sound.
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Old 05-09-23, 03:07 PM
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Originally Posted by joeruge
I also used the method discussed by Sheldon Brown (https://www.sheldonbrown.com/synchain.html) to minimise differences in tension from rotational position.
I'll second Sheldon Brown's approach. While I was a little intimidated at first, it actually works very well, and it's not that hard to do. Highly recommended.
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Old 05-10-23, 08:47 AM
  #31  
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Originally Posted by TobyGadd
I'll second Sheldon Brown's approach. While I was a little intimidated at first, it actually works very well, and it's not that hard to do. Highly recommended.
I agree this should be tried first. I my case it didnít work which is why I went down the rabbit hole I did. It should not have to be this way but unfortunately it is in far to many instances.

if the measured runout moves into the acceptable range, terrific. If not try rotating a ring one bolt position at a time until you achieve success.
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Old 05-10-23, 11:08 AM
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Originally Posted by Alcanbrad
I agree this should be tried first. I my case it didnít work which is why I went down the rabbit hole I did. It should not have to be this way but unfortunately it is in far to many instances.

if the measured runout moves into the acceptable range, terrific. If not try rotating a ring one bolt position at a time until you achieve success.
Your approach is very thorough and useful. Thanks for sharing it!
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Old 06-21-23, 02:58 AM
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Originally Posted by TobyGadd
Your approach is very thorough and useful. Thanks for sharing it!
Indeed!
I recently removed the stokers chainset to change chainrings. When I refitted the Gates timing belt it would slowly creep of the rear cog untill it rubbed the frame. I removed it and refitted it the other way round, and all was good. Are Gates belt directional?
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Old 08-20-23, 03:40 PM
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Originally Posted by Alcanbrad
The stoker bottom bracket develops this incredibly annoying click at a given orientation of the crank set. It will only do this when all 4 of our feet are on the pedals. With any combination of 3 or less feet on the pedals, no click, 4 feet, click. I replace either the entire bottom bracket or just the bearings and the click disappears.... for a few hundred miles, then - click click click.
This has been a great discussion. But I'd love to know if you successfully eliminated the clicking without having to keep replacing the bottom bracket.
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Old 08-21-23, 01:47 AM
  #35  
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Originally Posted by Philly Tandem
I put a Gates belt on our Santana Arriva last year and now you guys have me all stressed out! All this tech-speak hurts my tiny English-major brain...
Well, Philly, if itís any comfort for you, in the past 12 or so years we have ridden over 30,000 miles with the original Gates belt on our Macchiato with no problems with belt or BBS.
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Old 08-21-23, 05:40 AM
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Originally Posted by TobyGadd
This has been a great discussion. But I'd love to know if you successfully eliminated the clicking without having to keep replacing the bottom bracket.
So far so good. The current bottom bracket is surviving longer than before. Fingers continue to be crossed.

Originally Posted by Artmo
Well, Philly, if itís any comfort for you, in the past 12 or so years we have ridden over 30,000 miles with the original Gates belt on our Macchiato with no problems with belt or BBS.
I believe my issues are due to poor manufacturing of the crank(s). Iíve stated before that this shouldnít be the case, especially at the price points of these products, however, the evidence is abundant that the bicycle industry is doing a poor job insuring an acceptable level of quality. It could do better.
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Old 08-21-23, 05:42 AM
  #37  
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AND we’re now over 45,000 miles on our original Gates belts on our Equator with no problems with belt or BBS.
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Old 08-21-23, 10:17 AM
  #38  
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Originally Posted by Alcanbrad
After all the comments and trying with the belt tension looser, I believe that in addition to having excessive runout, I have been running the belt way too tight which is likely my problem (I never could get a consistent tone out of the belt strumming method). To set the looser tension I choose the limit to be just a bit tighter than the belt being able to climb out of the center track when slowly turning the crank and pushing the belt sideways just ahead of where the belt met the ring. If the belt climbed out of the center track and started to ride on top of the ring, I backed off and adjusted the eccentric just a bit tighter. Riding it over the weekend it performed well, but I still need to replace the BB (or bearings) as these are ruined. I believe the belt tension measures in the low 30lb range and the difference due to runout is fairly small.

I'd be curious of how others determine "loose" as "loose enough" or "too loose".
I'm another one who believes that the tone method of judging belt tension results in unnecessary BB friction and wear. One wants it just tight enough that it doesn't jump a tooth when the captain hammers OOS at a low cadence. I go this criterium: Total movement up and down is about 1". I just checked my belt - it's 1.25". Works fine. This tension may only work for the centertrack belts.
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