Drivetrain Problems / anger management !
bertypreston
Posts: 158
Can anyone advise ?
I have been having alot of trouble with my gears for the last 6 months !
Symptoms
The chain wont stay where its told especially on bumpy trails, it always shifts back to middle or small ring if i back pedal ,shifting at the front especially to the big ring is awfull. Its so unreliable that i often cant react in time to trial conditions and i dont have any confidence in it when i need to power out . which in short is ruining most of my rides.
I was certain that buying a new XT front mech would sort it and i had it fitted at my local bike shop, i explained to the shop the above problems. They fitted it but when i colleced it it was exactly the same (struggled shifting to big and drops back off big) with the shiny new mech !
i told them this and the chap said that it was cos i was putting to much pressure on the pedals whilst changing and going too slow to change into big ring anyway, which sounded like b*ll*cks. took it home and rode it for a week, didnt get any better, took it back explained and left it with them.
just picked it up again yesterday and it seemed much better in the car park, however just got back from another ruined ride at cannock, all the gremlins are back.
im at my wits end with the bike and the bike shop, who cant seem to sort it either (not going there again)
having already changed the mech, my new suspects are :
crankset - truative ? 2 years old came with the bike (giant xtc se 06) could this be worn out?
chain length - SRAM £20 ish cant remember model but its one with the easy fit link -fitted this my self !!! measured it againt the old one (shimano H?) and removed links to it was the same length. could this be too long or short ?
rear cassette - had a new rear cassette with new wheel but the biggest ring (and therefore the others) are smaller than the old one (which i still have) - is this causing probs ?
shifter - original (2 years old) deore rapid fire - could this be worn out.
thanks for reading all that, i'd really appreciate some advice as im dangerously close to chucking the bike off a bridge ! and reaching for my credit card for a massive splurge.
Rob
I have been having alot of trouble with my gears for the last 6 months !
Symptoms
The chain wont stay where its told especially on bumpy trails, it always shifts back to middle or small ring if i back pedal ,shifting at the front especially to the big ring is awfull. Its so unreliable that i often cant react in time to trial conditions and i dont have any confidence in it when i need to power out . which in short is ruining most of my rides.
I was certain that buying a new XT front mech would sort it and i had it fitted at my local bike shop, i explained to the shop the above problems. They fitted it but when i colleced it it was exactly the same (struggled shifting to big and drops back off big) with the shiny new mech !
i told them this and the chap said that it was cos i was putting to much pressure on the pedals whilst changing and going too slow to change into big ring anyway, which sounded like b*ll*cks. took it home and rode it for a week, didnt get any better, took it back explained and left it with them.
just picked it up again yesterday and it seemed much better in the car park, however just got back from another ruined ride at cannock, all the gremlins are back.
im at my wits end with the bike and the bike shop, who cant seem to sort it either (not going there again)
having already changed the mech, my new suspects are :
crankset - truative ? 2 years old came with the bike (giant xtc se 06) could this be worn out?
chain length - SRAM £20 ish cant remember model but its one with the easy fit link -fitted this my self !!! measured it againt the old one (shimano H?) and removed links to it was the same length. could this be too long or short ?
rear cassette - had a new rear cassette with new wheel but the biggest ring (and therefore the others) are smaller than the old one (which i still have) - is this causing probs ?
shifter - original (2 years old) deore rapid fire - could this be worn out.
thanks for reading all that, i'd really appreciate some advice as im dangerously close to chucking the bike off a bridge ! and reaching for my credit card for a massive splurge.
Rob
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Comments
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Does sound like to me a combo of worn rings and shifting with pressure on the cranks. Ease off when shifting!
Also is the chainline correct? Is the front chainset sat too far out board? And what rear cog are you in when it jumps off the front?0 -
are the cables 2 years old as well?"Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
s - have tried easing off, its just as poor & i wouldnt know how to tell if chain line is off, and come to think of it the bigger rear cogs.
n - both cables are <6 months old
am considering the buying shimano slx triple m660 chainset at chainreaction (£79) and getting it fitted somewhere else (<£20) - i could probably attempt this my self but it wouldnt be done right and i'd have to spend more buying tools + id have peace of mind peace of mind.0 -
Ah, think I may have an idea.
Using the big rear cogs, and big front chainrings skews the chain at an angle, and makes it much more likely to drop of the front.
This gear you can replicate in the middle chainring anyway.
42/28 = 1.5 (big chainring, biggish rear cog)
In the middle chainring
32/21 = 1.52
Practically the same gear, straighter chain! Plus a lot less wear on the chainrings and chain.
So I have to say I think the shop is right in some repects!0 -
i appreciate the big front to big back is alot to ask and thats its more likely to fail in that combo but its not just there, its unreliable in all combinations. considering the bike came with alivio front and deore back , these shifted great , i mean serioiusly no probs untill i foolishly decided to "upgrade" both at the same time after breaking a rear mech.
There is definetly something fundamentally wrong with my current set up which needs rectifying.0 -
Can you post a close up pic of the chainrings? So we can see the teeth profile?0
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took photos - how do i put them on here ?0
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Ah, you need to upload elsewhere, then link in.0
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bertypreston wrote:took photos - how do i put them on here ?
Forum FAQ's
http://www.bikeradar.com/forum/viewforum.php?f=40029"Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
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not the best angle to look at teeth. but they do look fairly worn.
picture this way would be better.
this is a new shimano ring for you to reference to. clicky for bigger."Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
Parktools :?:SheldonBrown0 -
Yes, I can see wear too. Plus looks like a lot of very thick crud on the drivetrain in general.0
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also, I wouldn't bother much with the SLX chainset....just go for the deore one instead (about £40 including BB)....it works a treat.Whenever I see an adult on a bicycle, I believe in the future of the human race.
H.G. Wells.0 -
is the worn teeth a likely cause for the chain dropping back ?
as for the gunge i had just got back from a ride when i took the photos.0 -
Possibly - it is difficult to tell from here, but certainly plausible. Back pedalling with a slightly sticky freehub can cause it to drop too.
Chainline - measure from centre of seattube to centre of middle ring. Ideally wants to be between 47 and 50mm.0 -
right then, im going to lube the free hub as best as possible and replace chainrings/crankset. Ill def check out the deore one ,but i usually try to upgrade when something needs replacing.0
