Something is jamming the drivechain, but what is it?
04-07-08, 04:27 AM
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Something is jamming the drivechain, but what is it?
Hello folks, I have just gotten back from an interesting ride. First...some background.
The bike is a 2006 Trek 3900 (Acera rear der and SIS front der). Those are the specs I can remember and I think are related to this issue. This afternoon I just changed the tires to slicks from knobbie ones of course which required removal and replacements of the wheels. Something I have done before with no dramas.
On my ride home while gearing down to go up a hill suddenly the everything seizes up, I am unable to pedal or do anything. The wheels aren't locked up so I still have a little momentum. So I stop (no choice about that) pull the bike off to the side and have a look. The chain looks fine, and on the cogs, nothing obvious stuck anywhere it shouldn't be. So I try the pedals again, suddenly everything is working fine again. Not even any gear grind or other funny noises.
So off I go again, but the same thing happens on the next hill. I pull aside, have a look, looks find, try the pedals and it's working fine again. So I ride home without any more dramas, but by this time there aren't any hills left anyway. I am pretty sure that each time I was gearing down using the front derailluer from middle to lowest gear.
So, does anyone have any ideas what of it may be?
Or is there something I could easily investigate myself?
I just hope it's not something permanent I have done to it while changing the wheels over.
If there is any more information I could post that could help you help me just let me know and I'll try to find it out.
Thanks.
The bike is a 2006 Trek 3900 (Acera rear der and SIS front der). Those are the specs I can remember and I think are related to this issue. This afternoon I just changed the tires to slicks from knobbie ones of course which required removal and replacements of the wheels. Something I have done before with no dramas.
On my ride home while gearing down to go up a hill suddenly the everything seizes up, I am unable to pedal or do anything. The wheels aren't locked up so I still have a little momentum. So I stop (no choice about that) pull the bike off to the side and have a look. The chain looks fine, and on the cogs, nothing obvious stuck anywhere it shouldn't be. So I try the pedals again, suddenly everything is working fine again. Not even any gear grind or other funny noises.
So off I go again, but the same thing happens on the next hill. I pull aside, have a look, looks find, try the pedals and it's working fine again. So I ride home without any more dramas, but by this time there aren't any hills left anyway. I am pretty sure that each time I was gearing down using the front derailluer from middle to lowest gear.
So, does anyone have any ideas what of it may be?
Or is there something I could easily investigate myself?
I just hope it's not something permanent I have done to it while changing the wheels over.
If there is any more information I could post that could help you help me just let me know and I'll try to find it out.
Thanks.
Last edited by damnable; 04-07-08 at 05:31 AM.
04-07-08, 06:13 AM
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You need to stop mashing the cranks with Lance armstrong effort when you're shifting. Try light pedalling when shifting. Note that we haven't ruled out anything mechanical that would make this problem worse than it could be.
04-07-08, 07:10 AM
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I think the front shifting needs a bit of adjusting but, as noted, shift earlier, particularly in front. I expect the problem was the chain not releasing cleanly from the larger chainring due to the high chain tension.
