New Co-Motion - skipping/slipping gear on steep climb
10-14-14, 01:18 PM
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New Co-Motion - skipping/slipping gear on steep climb
Hello everyone,
New forum member, relatively new to tandeming, but my wife and I are putting on lots of miles and loving the sport. Reading this forum has helped with my research and decision making when it came to buying a new tandem! Thank you!
We graduated from an old Burley Rock n' Roll and recently took delivery of a new Primera Co-Pilot. We love it and are very excited about our purchase and touring with our tandem. With one exception that I cannot figure out:
On every ride from our home, we have to climb a very steep, but short, hill. It's about 200-250 yards long. I ride it every day on my half-bike commute, and we've made it dozens of times on the Burley. When riding the hill on the Co-Motion, as we get to the point where the incline pitches steeply up, there is a startlingly unpleasant grinding and our cranks spin freely (nearly threw us from the bike the first time). I have done quite a bit of investigative troubleshooting and determined that it happens only in the granny (30T) chainring in the 28, 24, and 21T cogs. If in the 30x32, it doesn't happen. The grinding/slipping happens under the same conditions when I climb the hill alone without my stoker adding torque/weight. Have not tried the climb in the middle chainring - too steep.
The shifting is otherwise perfectly adjusted, and I mean perfect. After this started happening, I made sure the chain was well-lubricated, was the appropriate length, and the B-tension screw was adjusted properly. The bike is brand new -- new drivetrain with fewer than 150 miles on it. As a further troubleshooting measure, I even adjusted the barrel adjusters on the rear derailleur 3/4 turn in either direction, just to make sure I wasn't crazy in thinking the shifting adjustment was perfect. Didn't change the situation, other than making the chain rub slightly. BTW, did I mention that every time I made an adjustment I had to (attempt to) ride that blasted hill again!?!
One problem is that I'm not even 100% certain what's slipping/grinding. I believe it to be happening at the rear of the bike and not at the chainrings, but I can't be certain. I've had my wife try to walk/jog alongside when it happens, but she doesn't ever see what causes the sound or what's going on with the cassette. I cannot ride the hill and look down and back because the hill is too steep and I would crash. When I stop the bike immediately upon the sound, the chain is not derailed or in a different gear than when I started, and nothing looks amiss. It only happens under high torque loads and I cannot duplicate it on any normal climbs or in the work stand. When I walk it up to the top of the hill and ride off in the same gear without shifting, it works just fine under low torque.
The bike has new Spinergy TX2 wheels, 105 3x10 drivetrain, and an XT 11-32 cassette. As I said, it rides and shifts beautifully at all other times, even during normal climbs.
I've worked on bikes for a long time and am a fairly proficient amatuer bike mechanic, but this has stumped me. I've never experienced anything similar, although, admittedly, this is my first experience with a 10-speed cassette.
Do any of you have ideas or suggestions what to try? My wife and I are just heartbroken that our new, expensive tandem can't make it up steep climbs.
Thanks in advance,
Andrew
P.S. Ric and Marcia at House of Tandems have been absolutely wonderful, in both the purchase and post-purchase support. However, they're a 3-hour drive away and there are no hills close to them that are steep enough to duplicate the condition. Ric is just as confounded as I am, so I'm posting here to see if we get any good ideas. He, too, has never seen anything like this, and he's worked on a lot of tandems.
New forum member, relatively new to tandeming, but my wife and I are putting on lots of miles and loving the sport. Reading this forum has helped with my research and decision making when it came to buying a new tandem! Thank you!
We graduated from an old Burley Rock n' Roll and recently took delivery of a new Primera Co-Pilot. We love it and are very excited about our purchase and touring with our tandem. With one exception that I cannot figure out:
On every ride from our home, we have to climb a very steep, but short, hill. It's about 200-250 yards long. I ride it every day on my half-bike commute, and we've made it dozens of times on the Burley. When riding the hill on the Co-Motion, as we get to the point where the incline pitches steeply up, there is a startlingly unpleasant grinding and our cranks spin freely (nearly threw us from the bike the first time). I have done quite a bit of investigative troubleshooting and determined that it happens only in the granny (30T) chainring in the 28, 24, and 21T cogs. If in the 30x32, it doesn't happen. The grinding/slipping happens under the same conditions when I climb the hill alone without my stoker adding torque/weight. Have not tried the climb in the middle chainring - too steep.
The shifting is otherwise perfectly adjusted, and I mean perfect. After this started happening, I made sure the chain was well-lubricated, was the appropriate length, and the B-tension screw was adjusted properly. The bike is brand new -- new drivetrain with fewer than 150 miles on it. As a further troubleshooting measure, I even adjusted the barrel adjusters on the rear derailleur 3/4 turn in either direction, just to make sure I wasn't crazy in thinking the shifting adjustment was perfect. Didn't change the situation, other than making the chain rub slightly. BTW, did I mention that every time I made an adjustment I had to (attempt to) ride that blasted hill again!?!
One problem is that I'm not even 100% certain what's slipping/grinding. I believe it to be happening at the rear of the bike and not at the chainrings, but I can't be certain. I've had my wife try to walk/jog alongside when it happens, but she doesn't ever see what causes the sound or what's going on with the cassette. I cannot ride the hill and look down and back because the hill is too steep and I would crash. When I stop the bike immediately upon the sound, the chain is not derailed or in a different gear than when I started, and nothing looks amiss. It only happens under high torque loads and I cannot duplicate it on any normal climbs or in the work stand. When I walk it up to the top of the hill and ride off in the same gear without shifting, it works just fine under low torque.
The bike has new Spinergy TX2 wheels, 105 3x10 drivetrain, and an XT 11-32 cassette. As I said, it rides and shifts beautifully at all other times, even during normal climbs.
I've worked on bikes for a long time and am a fairly proficient amatuer bike mechanic, but this has stumped me. I've never experienced anything similar, although, admittedly, this is my first experience with a 10-speed cassette.
Do any of you have ideas or suggestions what to try? My wife and I are just heartbroken that our new, expensive tandem can't make it up steep climbs.
Thanks in advance,
Andrew
P.S. Ric and Marcia at House of Tandems have been absolutely wonderful, in both the purchase and post-purchase support. However, they're a 3-hour drive away and there are no hills close to them that are steep enough to duplicate the condition. Ric is just as confounded as I am, so I'm posting here to see if we get any good ideas. He, too, has never seen anything like this, and he's worked on a lot of tandems.
10-14-14, 03:06 PM
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Hello everyone,
New forum member, relatively new to tandeming, but my wife and I are putting on lots of miles and loving the sport. Reading this forum has helped with my research and decision making when it came to buying a new tandem! Thank you!
We graduated from an old Burley Rock n' Roll and recently took delivery of a new Primera Co-Pilot. We love it and are very excited about our purchase and touring with our tandem. With one exception that I cannot figure out:
On every ride from our home, we have to climb a very steep, but short, hill. It's about 200-250 yards long. I ride it every day on my half-bike commute, and we've made it dozens of times on the Burley. When riding the hill on the Co-Motion, as we get to the point where the incline pitches steeply up, there is a startlingly unpleasant grinding and our cranks spin freely (nearly threw us from the bike the first time). I have done quite a bit of investigative troubleshooting and determined that it happens only in the granny (30T) chainring in the 28, 24, and 21T cogs. If in the 30x32, it doesn't happen. The grinding/slipping happens under the same conditions when I climb the hill alone without my stoker adding torque/weight. Have not tried the climb in the middle chainring - too steep.
The shifting is otherwise perfectly adjusted, and I mean perfect. After this started happening, I made sure the chain was well-lubricated, was the appropriate length, and the B-tension screw was adjusted properly. The bike is brand new -- new drivetrain with fewer than 150 miles on it. As a further troubleshooting measure, I even adjusted the barrel adjusters on the rear derailleur 3/4 turn in either direction, just to make sure I wasn't crazy in thinking the shifting adjustment was perfect. Didn't change the situation, other than making the chain rub slightly. BTW, did I mention that every time I made an adjustment I had to (attempt to) ride that blasted hill again!?!
One problem is that I'm not even 100% certain what's slipping/grinding. I believe it to be happening at the rear of the bike and not at the chainrings, but I can't be certain. I've had my wife try to walk/jog alongside when it happens, but she doesn't ever see what causes the sound or what's going on with the cassette. I cannot ride the hill and look down and back because the hill is too steep and I would crash. When I stop the bike immediately upon the sound, the chain is not derailed or in a different gear than when I started, and nothing looks amiss. It only happens under high torque loads and I cannot duplicate it on any normal climbs or in the work stand. When I walk it up to the top of the hill and ride off in the same gear without shifting, it works just fine under low torque.
The bike has new Spinergy TX2 wheels, 105 3x10 drivetrain, and an XT 11-32 cassette. As I said, it rides and shifts beautifully at all other times, even during normal climbs.
I've worked on bikes for a long time and am a fairly proficient amatuer bike mechanic, but this has stumped me. I've never experienced anything similar, although, admittedly, this is my first experience with a 10-speed cassette.
Do any of you have ideas or suggestions what to try? My wife and I are just heartbroken that our new, expensive tandem can't make it up steep climbs.
Thanks in advance,
Andrew
P.S. Ric and Marcia at House of Tandems have been absolutely wonderful, in both the purchase and post-purchase support. However, they're a 3-hour drive away and there are no hills close to them that are steep enough to duplicate the condition. Ric is just as confounded as I am, so I'm posting here to see if we get any good ideas. He, too, has never seen anything like this, and he's worked on a lot of tandems.
New forum member, relatively new to tandeming, but my wife and I are putting on lots of miles and loving the sport. Reading this forum has helped with my research and decision making when it came to buying a new tandem! Thank you!
We graduated from an old Burley Rock n' Roll and recently took delivery of a new Primera Co-Pilot. We love it and are very excited about our purchase and touring with our tandem. With one exception that I cannot figure out:
On every ride from our home, we have to climb a very steep, but short, hill. It's about 200-250 yards long. I ride it every day on my half-bike commute, and we've made it dozens of times on the Burley. When riding the hill on the Co-Motion, as we get to the point where the incline pitches steeply up, there is a startlingly unpleasant grinding and our cranks spin freely (nearly threw us from the bike the first time). I have done quite a bit of investigative troubleshooting and determined that it happens only in the granny (30T) chainring in the 28, 24, and 21T cogs. If in the 30x32, it doesn't happen. The grinding/slipping happens under the same conditions when I climb the hill alone without my stoker adding torque/weight. Have not tried the climb in the middle chainring - too steep.
The shifting is otherwise perfectly adjusted, and I mean perfect. After this started happening, I made sure the chain was well-lubricated, was the appropriate length, and the B-tension screw was adjusted properly. The bike is brand new -- new drivetrain with fewer than 150 miles on it. As a further troubleshooting measure, I even adjusted the barrel adjusters on the rear derailleur 3/4 turn in either direction, just to make sure I wasn't crazy in thinking the shifting adjustment was perfect. Didn't change the situation, other than making the chain rub slightly. BTW, did I mention that every time I made an adjustment I had to (attempt to) ride that blasted hill again!?!
One problem is that I'm not even 100% certain what's slipping/grinding. I believe it to be happening at the rear of the bike and not at the chainrings, but I can't be certain. I've had my wife try to walk/jog alongside when it happens, but she doesn't ever see what causes the sound or what's going on with the cassette. I cannot ride the hill and look down and back because the hill is too steep and I would crash. When I stop the bike immediately upon the sound, the chain is not derailed or in a different gear than when I started, and nothing looks amiss. It only happens under high torque loads and I cannot duplicate it on any normal climbs or in the work stand. When I walk it up to the top of the hill and ride off in the same gear without shifting, it works just fine under low torque.
The bike has new Spinergy TX2 wheels, 105 3x10 drivetrain, and an XT 11-32 cassette. As I said, it rides and shifts beautifully at all other times, even during normal climbs.
I've worked on bikes for a long time and am a fairly proficient amatuer bike mechanic, but this has stumped me. I've never experienced anything similar, although, admittedly, this is my first experience with a 10-speed cassette.
Do any of you have ideas or suggestions what to try? My wife and I are just heartbroken that our new, expensive tandem can't make it up steep climbs.
Thanks in advance,
Andrew
P.S. Ric and Marcia at House of Tandems have been absolutely wonderful, in both the purchase and post-purchase support. However, they're a 3-hour drive away and there are no hills close to them that are steep enough to duplicate the condition. Ric is just as confounded as I am, so I'm posting here to see if we get any good ideas. He, too, has never seen anything like this, and he's worked on a lot of tandems.
i wish i could offer some input. until you mentioned yours is a very new drivetrain, i was thinking your cassette needed replacing. i suppose it is possible, though, but unlikely. good luck with it.
you mentioned rick and marcia becker. i bought a davinci from them 2 years ago, and love it. i've known them since '98 when they owned a humble bike shop in Katy, TX, before they sold it and went into tandem specialty. they're good folks.
10-14-14, 03:51 PM
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Check your chain. Seems crazy but my 2011 Trek Madone 5.2 came with the chain installed backwards - Ultegra chain. I'm fairly certain that XT cassette requires a Dyna-sys-type, directional chain to work best. My Madone would shift oddly and skip, similar to your description, until I discovered the eff up and installed it properly.
You mentioned that the chain is in the correct gear so I may be way off. The only other times I've experienced a similar phenomenon was when my XT MTB hub was damaged. Required a new freehub body to fix. And, when my brother-in-law changed his chain but not any gearing; the chain would skip under heavy torque on the front rings. He changed the cassette and rings and everything was fixed.
You mentioned that the chain is in the correct gear so I may be way off. The only other times I've experienced a similar phenomenon was when my XT MTB hub was damaged. Required a new freehub body to fix. And, when my brother-in-law changed his chain but not any gearing; the chain would skip under heavy torque on the front rings. He changed the cassette and rings and everything was fixed.
10-14-14, 04:13 PM
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Can you reproduce the problem on a gentler slope while applying the brake? This might allow you to reproduce it at the shop for the mechanic.
10-14-14, 04:27 PM
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I would remove the cassette and look at the freehub and inside the cassette to see if there is any damage.
10-14-14, 04:28 PM
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Weird problem since it does not happen in the big cog. The only problems I can think of are chain slipping, cog slipping, freehub slipping. so.....
First question:
The chain may be the problem. I would go ahead and change the chain because it is no cost (you will need a new chain in a few thousand miles anyway) and easy to do. I suggest a KMC 10 speed chain to stay away from Shimano's silly one directional chain issues.
Other ideas after the chain, although it would seem to me they would also be a problem in the big cog:
Is the cassette lock ring tight on the hub?
Have you pulled the cassette to see if it is damaged ?
Does the cassette slide on and off the freehub easily?
Does the freehub look OK?
Not sure how much trouble it is to pull the freehub off that hub but Ric might be able to guide you through that process to check the pawls and the tooth engagement.
Does the problem happen in the middle or large ring when in those same cogs? I realize you will have to try another hill, but on the steepest hill you can grunt up in the middle ring does it slip?
Swapping out rear wheels for a test might narrow the issue. You mention how far you are away from Ric. Are you in the DFW area?
You also might consider having your stoker or a friend captain and you stoke up the hill and watch while yourself while it happens.
First question:
The chain may be the problem. I would go ahead and change the chain because it is no cost (you will need a new chain in a few thousand miles anyway) and easy to do. I suggest a KMC 10 speed chain to stay away from Shimano's silly one directional chain issues.
Other ideas after the chain, although it would seem to me they would also be a problem in the big cog:
Is the cassette lock ring tight on the hub?
Have you pulled the cassette to see if it is damaged ?
Does the cassette slide on and off the freehub easily?
Does the freehub look OK?
Not sure how much trouble it is to pull the freehub off that hub but Ric might be able to guide you through that process to check the pawls and the tooth engagement.
Does the problem happen in the middle or large ring when in those same cogs? I realize you will have to try another hill, but on the steepest hill you can grunt up in the middle ring does it slip?
Swapping out rear wheels for a test might narrow the issue. You mention how far you are away from Ric. Are you in the DFW area?
You also might consider having your stoker or a friend captain and you stoke up the hill and watch while yourself while it happens.
Last edited by waynesulak; 10-14-14 at 04:38 PM.
10-14-14, 04:50 PM
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The chain may be the problem. I would go ahead and change the chain because it is no cost (you will need a new chain in a few thousand miles anyway) and easy to do. I suggest a KMC 10 speed chain to stay away from Shimano's silly one directional chain issues.
Other ideas after the chain, although it would seem to me they would also be a problem in the big cog:
Is the cassette lock ring tight on the hub?
Have you pulled the cassette to see if it is damaged ?
Does the cassette slide on and off the freehub easily?
Does the freehub look OK?
Not sure how much trouble it is to pull the freehub off that hub but Ric might be able to guide you through that process to check the pawls and the tooth engagement.
Does the problem happen in the middle or large ring when in those same cogs? I realize you will have to try another hill, but on the steepest hill you can grunt up in the middle ring does it slip?
You mention how far you are away from Ric. Are you in the DFW area?
1) Pulled the cassette to inspect the splines and the freehub. Both the freehub and cassette are completely 100% undamaged. Look pristine.
2) I will double check the chain, directionally and for brand. I think it may be a KMC chain with a powerlink installed, but not 100% certain.
3) Haven't tried reproducing on a shallower climb with brake. However, I cannot reproduce on workstand with brake applied.
4) Cassette lock ring is torqued to spec. I double-checked that.
5) I opened up the freehub and looked at the pawls. It looks completely unworn, well lubricated (not sticking), and completely operational. Honestly, the pawls were my first thought, but it doesn't mesh with it not occurring in the largest cog. Also, those TX2 hubs look fairly beefy.
6) I'll see what I can do in the middle chainring on the hill on the 28 and 24 cog, but we've climbed other, lesser hills in that gear combination (as a team), stamping major torque and never had a slip.
7) We're in Austin (and haven't yet met other tandem teams, although looking forward to it).
Thanks again, and looking forward to more input.
10-14-14, 05:51 PM
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Maybe too much torque while climbing that darn hill?
Set up pedals 90 degrees OOP (out of phase) to see if that reduces the stress on drivetrain.
Easy and cheap to do/try. Photo of us on our old Co-Mo 900 degrees OOP
Pedal on!
Rudy and Kay/zonatandem
Set up pedals 90 degrees OOP (out of phase) to see if that reduces the stress on drivetrain.
Easy and cheap to do/try. Photo of us on our old Co-Mo 900 degrees OOP
Pedal on!
Rudy and Kay/zonatandem
10-14-14, 05:56 PM
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A friend had the exact problem you describe on a new Primera. Unfortunately for them they fell a couple of times before he figured out the problem (no physical injury but a very unhappy stoker). The net result was to replace the granny chain ring with a higher quality ring. The teeth actually sheared off. He was told the quality of the rings on that model are not very high.
10-15-14, 09:59 AM
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Congrats on the Primera, we have one and enjoy it a lot. I have upgraded ours to Rolf Tandem wheels with Hope rotors, original gates carbon timing belt, FSA Gossamer cranks, an 11-34 cassette, and a rear XT 9 speed deraileur (bike is otherwise Shimano 105).
There really aren't many things that can allow the pedals to spin freely...
We have tossed the chain in front once and that was exciting, but that condition remains after you stop.
Small ring does put the highest leverage and thus force loading into the drivetrain.
Largest rear cog does put chain into a tighter position but it is hard to believe that the chain would come out and skip over that many teeth on those two lower gears.
I understand your frustration diagnosing this. Things that you can just look down and see on a half bike are w-a-y back there out of sight on a tandem (have to detect rear flats by feel). So a thought: why not rig up a camera taking video back there as the problem occurs? Get some eyes on it. We have a rear rack on our Pimera so I can envision a stick and some duct tape with an iPhone would get the job done.
There really aren't many things that can allow the pedals to spin freely...
We have tossed the chain in front once and that was exciting, but that condition remains after you stop.
Small ring does put the highest leverage and thus force loading into the drivetrain.
Largest rear cog does put chain into a tighter position but it is hard to believe that the chain would come out and skip over that many teeth on those two lower gears.
I understand your frustration diagnosing this. Things that you can just look down and see on a half bike are w-a-y back there out of sight on a tandem (have to detect rear flats by feel). So a thought: why not rig up a camera taking video back there as the problem occurs? Get some eyes on it. We have a rear rack on our Pimera so I can envision a stick and some duct tape with an iPhone would get the job done.
10-15-14, 10:14 AM
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Congrats on the Primera, we have one and enjoy it a lot. I have upgraded ours to Rolf Tandem wheels with Hope rotors, original gates carbon timing belt, FSA Gossamer cranks, an 11-34 cassette, and a rear XT 9 speed deraileur (bike is otherwise Shimano 105).
There really aren't many things that can allow the pedals to spin freely...
We have tossed the chain in front once and that was exciting, but that condition remains after you stop.
Small ring does put the highest leverage and thus force loading into the drivetrain.
Largest rear cog does put chain into a tighter position but it is hard to believe that the chain would come out and skip over that many teeth on those two lower gears.
I understand your frustration diagnosing this. Things that you can just look down and see on a half bike are w-a-y back there out of sight on a tandem (have to detect rear flats by feel). So a thought: why not rig up a camera taking video back there as the problem occurs? Get some eyes on it. We have a rear rack on our Pimera so I can envision a stick and some duct tape with an iPhone would get the job done.
There really aren't many things that can allow the pedals to spin freely...
We have tossed the chain in front once and that was exciting, but that condition remains after you stop.
Small ring does put the highest leverage and thus force loading into the drivetrain.
Largest rear cog does put chain into a tighter position but it is hard to believe that the chain would come out and skip over that many teeth on those two lower gears.
I understand your frustration diagnosing this. Things that you can just look down and see on a half bike are w-a-y back there out of sight on a tandem (have to detect rear flats by feel). So a thought: why not rig up a camera taking video back there as the problem occurs? Get some eyes on it. We have a rear rack on our Pimera so I can envision a stick and some duct tape with an iPhone would get the job done.
We love the Primera as well; we, too, tricked it out with the Spinergy wheels, a Gates timing belt, TRP Spyres, and a Thudbuster. Now, if I could only get this issue sorted, we are psyched to start piling on the miles!
10-15-14, 10:43 AM
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A friend had the exact problem you describe on a new Primera. Unfortunately for them they fell a couple of times before he figured out the problem (no physical injury but a very unhappy stoker). The net result was to replace the granny chain ring with a higher quality ring. The teeth actually sheared off. He was told the quality of the rings on that model are not very high.
10-15-14, 11:31 AM
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Most likely the cassette. My wife and I are a strongish team who like to do 18-20% climbs. I had a similar issue as yourself a few years back. Ended up being the cassette. We find ourselves needing to replace our cassette every 3-6 months depending on how much climbing we do. The tremendous force of steep tandem climbing on the chain/cassette causes rapid stretch and wearing.
10-15-14, 11:41 AM
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Even with a brand-new cassette? Also, in response to the out-of-phase suggestion, it also consistently happens when riding the tandem solo.
10-15-14, 06:14 PM
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I know it's a reach -- but this sounds like a partial autoshift caused by frame flex or a hub with some play. On the other hand your tweaking with the barrel adjuster should have had an effect on that (making it better or worse), so maybe it doesn't sound like that after all.
Please post when you figure this out!
Please post when you figure this out!
10-15-14, 07:47 PM
#16
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I had a brand new Phil Wood hub do similar and sent it back to Phil for warranty. Had less than 150 miles on it. They machined out and replaced the internal ratchet mechanism. Yes a brand new $500 Phil Wood hub with a defective ratchet mechanism. If your tandem dealer can loan you another tandem wheel to try it might help you pinpoint the problem.
10-16-14, 10:58 AM
#17
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My take is that the chainline is biased towards the middle chain-ring. I do not at all find it surprising that there is chain skip using the 21T with the granny ring. I get chain rub making two shifts in the rear and have to trim the front derraileur after three. We have a 3x9 Shimano 105 setup as well. We changed our 42T middle ring to a 39. The granny has less work to do and there isn't as much of a temptation to use smaller cogs with the granny. FWIW. Total setup is: 52-39-24 x 11-25. I like the ability to make small variations at the rear and you lose that with ??-32/34 setups. FWIW
H
Edit: Just putting it out there.. once when our rig was doing this it turned out that the rear wheel was twisted in the drop-out! This is easy to do when you live in hilly territory and are putting very high stresses on your quick release.
H
Edit: Just putting it out there.. once when our rig was doing this it turned out that the rear wheel was twisted in the drop-out! This is easy to do when you live in hilly territory and are putting very high stresses on your quick release.
Last edited by Leisesturm; 10-16-14 at 11:02 AM.
10-16-14, 07:29 PM
#18
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My take is that the chainline is biased towards the middle chain-ring. I do not at all find it surprising that there is chain skip using the 21T with the granny ring. I get chain rub making two shifts in the rear and have to trim the front derraileur after three. We have a 3x9 Shimano 105 setup as well. We changed our 42T middle ring to a 39. The granny has less work to do and there isn't as much of a temptation to use smaller cogs with the granny. FWIW. Total setup is: 52-39-24 x 11-25. I like the ability to make small variations at the rear and you lose that with ??-32/34 setups. FWIW
H
Edit: Just putting it out there.. once when our rig was doing this it turned out that the rear wheel was twisted in the drop-out! This is easy to do when you live in hilly territory and are putting very high stresses on your quick release.
H
Edit: Just putting it out there.. once when our rig was doing this it turned out that the rear wheel was twisted in the drop-out! This is easy to do when you live in hilly territory and are putting very high stresses on your quick release.
10-19-14, 12:55 PM
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Cautiously optimistic
Well, thanks to Ric at House of Tandems, I think we may have things fixed. Ric sent me a new FSA 30t small chainring and told me just to test that first. The stock one I took off looked just fine, with no wear. It looked basically brand new, so I had my doubts. But I did what I was told, torqued things down, and attacked the hill by myself. (didn't want to chance crashing my dear stoker!). Low and behold, I made it up the hill for the first time ever (in the offending gear combo) with no slipping.
Today, we went out as a team to give it a go. Qualified success! I say qualified because there is an occasional clicking noise that my wife says coincides with our right foot power stroke coming from the front chaining, but no slipping at all. She's a bit nervous about the clicking, and I can feel it through my pedals. Definitely torque related. However, I'm happy because it does appear that the slipping and grinding was coming from the small chainring. Swapping to a new one seemed to have done the trick. I can't believe that Co-motion would stock such a poor quality chainring on a $5000 tandem, but hey.
Thanks everyone for the input. I'll report back as we get more miles on and see if the clicking condition worsens.
Today, we went out as a team to give it a go. Qualified success! I say qualified because there is an occasional clicking noise that my wife says coincides with our right foot power stroke coming from the front chaining, but no slipping at all. She's a bit nervous about the clicking, and I can feel it through my pedals. Definitely torque related. However, I'm happy because it does appear that the slipping and grinding was coming from the small chainring. Swapping to a new one seemed to have done the trick. I can't believe that Co-motion would stock such a poor quality chainring on a $5000 tandem, but hey.
Thanks everyone for the input. I'll report back as we get more miles on and see if the clicking condition worsens.
10-20-14, 08:46 AM
#21
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Good to hear you have it figured out and got great support from your dealer. For grins I just measured the Truvative Elita and FSA Gossamer and the Truvative 30t chainring teeth are 10/1000 of an inch shorter by my rough measurement.
I have to admit to having similar thoughts once or twice myself... but we do have to remember that it is really a $3500 tandem with $1500 worth of S&S couplers on it 
We started out with "stock" 40 spoke wheels and later upgraded to the Rolfs. I decided to setup the new wheels with a new 11-34 cassette for a bit lower gear (original was 11-32). As I started researching things I found that the Shimano specifications for the 105 deraileurs did not support the combination we had. They did work but just were not within Shimano spec: the front 105 is only spec'd for up to a 50 tooth chainring and the rear for up to a 28 tooth cassette.
I have since upgraded to a front Ultegra and rear XT deraileurs which are within spec and it all works about the same as it did before. More spare parts
Note that the Primera is a "value" bike for Co-Motion being the least expensive tandem they sell. Not that anything on it is really cheap, Shimano 105 are generally worthy components. And having done a factory tour I can vouch that the frame is built the same and with the same attention to detail as all of the Co-Motions. We decided it was worth the extra $100 to choose our frame color so you cannot tell it is a steel frame Primera unless you look closely or know exactly what to look for. And nobody looks that closely. We get a lot of 'nice bike' comments and a few go so far as to note and be impressed that it is a Co-Motion. We enjoy the bike a lot and don't regret our purchase.
We started out with "stock" 40 spoke wheels and later upgraded to the Rolfs. I decided to setup the new wheels with a new 11-34 cassette for a bit lower gear (original was 11-32). As I started researching things I found that the Shimano specifications for the 105 deraileurs did not support the combination we had. They did work but just were not within Shimano spec: the front 105 is only spec'd for up to a 50 tooth chainring and the rear for up to a 28 tooth cassette.
I have since upgraded to a front Ultegra and rear XT deraileurs which are within spec and it all works about the same as it did before. More spare parts
Note that the Primera is a "value" bike for Co-Motion being the least expensive tandem they sell. Not that anything on it is really cheap, Shimano 105 are generally worthy components. And having done a factory tour I can vouch that the frame is built the same and with the same attention to detail as all of the Co-Motions. We decided it was worth the extra $100 to choose our frame color so you cannot tell it is a steel frame Primera unless you look closely or know exactly what to look for. And nobody looks that closely. We get a lot of 'nice bike' comments and a few go so far as to note and be impressed that it is a Co-Motion. We enjoy the bike a lot and don't regret our purchase.
10-20-14, 02:04 PM
#22
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Glad you have a potential solution. I'm kind of surprised, however, that nobody mentioned the possibility that your belt was jumping. We had this happen last summer while touring Corsica. Couldn't figure out why we were skipping under big power, then noticed reduced tension in the belt and sure enough our eccentric had rotated. I apparently had not tightened it enough when we put the bike together on arrival. I'll offer this to the end of this thread, even though it appears not to have been your problem, but rather so the next person searching on this might find an alternative possibility.
Last edited by 2frmMI; 10-26-14 at 08:08 PM. Reason: spelling, sheesh!
10-22-14, 09:07 PM
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Thanks for the private message. I can't reply privately since I am a new member, so I'll just reply here:
So, that was my very first thought, when it first happened. The thing was, we were both still in perfect sync, even after several occurrences. Also, the belt was brand new and was probably on the slightly tight side of the tension scale. Thanks for the input on the thread though. As I said, when it first happened, I was just sure the belt was slipping. Turns out that it appears to be the small chainring.
So, that was my very first thought, when it first happened. The thing was, we were both still in perfect sync, even after several occurrences. Also, the belt was brand new and was probably on the slightly tight side of the tension scale. Thanks for the input on the thread though. As I said, when it first happened, I was just sure the belt was slipping. Turns out that it appears to be the small chainring.
10-23-14, 10:07 AM
#24
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H
