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Mechanical Mystery
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i know my way around tuning up my newer road bikes. i can dial in 9sp da & 10sp campy very nicely, but my commuter bike is throwing me for a loop.

14 year old rigid mtn bike, with loads of miles. drivetrain is xt with 7 speed cassette. last year, i replaced chain & cassette. the shifter lines up the deraileur perfectly under each cog, but i can't ride in the 3 tall gears. i can shift through the 4 easy ones very buttery, but as soon as i get into the 3 harder ones..... it sounds & feels like it skips a tooth every time around (a slipping sensation). clunk! clunk! without a load, it shifts fine. but as soon as it has any load at all, it happens. why is it doing this, even when it's perfectly in-line with the cog?

it's not the hub, or else the easier gears would do it too?

thanks.....

It's not easy to juggle a pregnant wife and a troubled child, but somehow I managed to squeeze in 8 hours of TV a day - Homer Simpson
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Re: Mechanical Mystery [TheMonkey] [ In reply to ]
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Is your chain too long? its possible that the derailleur cant take up all the extra chain, thus not enough chain tension. also, is the chainline correct (ie correct bottom bracket). if the bottom bracket axel is too short, your chain might be too crossed over in the highest 3 gears, causing the chain to "want" to shift back over to a straighter chainline.

I cant really think of anything else off hand...

wilson
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Re: Mechanical Mystery [wilson] [ In reply to ]
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dirty cable?

stiff link?
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Re: Mechanical Mystery [t-t-n] [ In reply to ]
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Pedal backwards in any gear and you will see a stiff link right away.

Did you check to make sure that the plasic little shipping thingie was taken out the the cassette before it was installed? (yes I have seen that - this is the plastic clip that keeps all the gears together in the box)

The older chains just did not flex the way new ones do...that being said...if this is an old system...Hyperglide needs a Hyperglide chain...same for Ultraglide, Superglide, Astroglide and what ever the heck all the other ShimaNO chains and cogs were in the day. You may have a chain that is to wide or narrow, you may have a chain with smooth pins and you need not so smooth pins....god I love ShimaNo...now you have me thinking.



(BTW...I have a 1978 Basso with Campy Super Record on it that runs 100% with a new Record9 chain!)

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What if the Hokey Pokey is what it is all about?
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Re: Mechanical Mystery [Record9ti] [ In reply to ]
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record9ti wins points for consistancy on the shimNO thing. i have an old punk tee shirt around here someplace from back in the early mountain days which reads " i hated shimao before hating shimano was cool", that i should send you ! of course, one could note how campy punked even their OEM stalwart bianchi back when they went 10 speed and left them with a whole model year of obsolete bikes. . . . with more or less unprecented incompatibility ( not to mention unprecedented COST) - but where would the fun be in that ??

anyway, never underestimate the ability of a dirty cable loop to muck up indexing, particularly in the smaller cogs - that is where i would look first, myself.
Last edited by: t-t-n: Jun 9, 03 19:12
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Re: Mechanical Mystery [Record9ti] [ In reply to ]
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thanks for the ideas. i suppose i should re-cable, and also send the derailuer to the part cleaning tank. maybe not retracting enough?

record9ti - weren't you sick last year? has health squared up for you? as an aside - i laugh now every time i see your name pop up because of the chopping carrots story. i get it. it is really funny.

supposing that the chain is the wrong generation (hyper, super, astro....), wouldn't that create problems in the bigger cogs also? btw- astroglide was a lubricant that was part of a post-natal kit from the hospital from 4 out of 4 kids. isn't there some kind of name infringement there?

It's not easy to juggle a pregnant wife and a troubled child, but somehow I managed to squeeze in 8 hours of TV a day - Homer Simpson
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Re: Mechanical Mystery [TheMonkey] [ In reply to ]
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record9ti - weren't you sick last year? has health squared up for you? as an aside - i laugh now every time i see your name pop up because of the chopping carrots story. i get it. it is really funny.
I was, and "am" sick still I guess. I plan on racing this year...presuming that I dont break any bones (osteoporosis)...at this point I am in the "denial" stages of my illness and say "The hell with it". I would rather have quality of life (not being on hundreds of pills a month is a start towards quality) - than I would )quantity of life (in a drugged up state where the med's make me "feel" sick 24/7)

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What if the Hokey Pokey is what it is all about?
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Re: Mechanical Mystery [TheMonkey] [ In reply to ]
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thanks for the ideas. i suppose i should re-cable, and also send the derailuer to the part cleaning tank. maybe not retracting enough?


Check the chain carefully. A frozen or broken link will cause the probelm you described.

Larry
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