9 speed mech, 8 speed shifter?

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This topic has 10 replies, 7 voices, and was last updated 13 years ago by scaredypants.

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9 speed mech, 8 speed shifter?
tequilagrae
Free Member

I have a bike built from bits, it has old 8 speed trigger shifters, new cassette and the chain is from an old 6 speed bike(hardly used). I bought a mech from Decathlon that was listed as a 6/7/8 speed mech on the packet.
I can’t get it to shift all of the gears, only 7 at a time, not the top and the bottom gears and the same mechs are now listed as 6/7 speed.
I’m looking on ebay for a replacement and theres not many 8 speed, would a 9 speed mech work ok with my 8 speed setup?
Thanks

Grae

Posted 13 years ago

andrewh
Free Member

Nine speed mech will work fine with 8/9/10 speed cassette as they are all the same width, just with narrower sprockets and gaps in between for more gears.Same goes for 6/7.
Just make sure you avoid the SRAM/Shimano compatibility issue.
Take the mech back if it was wrongly described and get them to swap it.

Posted 13 years ago

tequilagrae
Free Member

Cool thankyou
ive been running the mech for a while just using 7 of the gears so i cant take it back now, only noticed the other day its now listed as 6/7 not 6/7/8

Posted 13 years ago

crotchrocket
Free Member

You prolly just need to back off the top and bottom stop screws. You might find this gives you enough latitude to set up the mech over the spread you need

Posted 13 years ago

bassspine
Free Member

8 speed cassette, 6 speed chain, n speed shifters. the chain’s too wide for the cassette and the shifter isn’t moving it the right distance sideways to shift properly.

(Old cycle mechanics rule: if it looks like it’s the limit screws it’s almost always something else)

Posted 13 years ago

tequilagrae
Free Member

It’s definetely not the stop screws, I’ve wound them both fully out and it still doesn’t have enough movement.
After a new mech the next this im trying is a new chain.
The chains I’ve seen are usually 5-8 speed ones then 9 speed ones, which type should i try?
http://www.decathlon.co.uk/EN/mtb-leasure-bike-gearing-3888473/
Thanks
Grae

Posted 13 years ago

bassspine
Free Member

shimano hg70
SRAM pc850
kmc z82

buy your parts from a bike shop, not a supermarket!

🙂

Posted 13 years ago

njee20
Free Member

Nine speed mech will work fine with 8/9/10 speed cassette as they are all the same width,

Not quite true, 10 speed MTB systems pull a different amount of cable, so the mechs aren’t interchangeable.

As for the problem, im dubious about the mech, agree with basspine, just go to your LBS, sure they’ll diagnose and potentially save you a load of hassle and money!

Posted 13 years ago

andrewh
Free Member

Nine speed mech will work fine with 8/9/10 speed cassette as they are all the same width,

Not quite true, 10 speed MTB systems pull a different amount of cable, so the mechs aren’t interchangeable.

Whoops, yes. Forgot about 10sp MTB stuff! Been using a nine speed XTR shadow on my 10 speed road bike.

Posted 13 years ago

cynic-al
Free Member

I can’t get it to shift all of the gears, only 7 at a time, not the top and the bottom gears and the same mechs are now listed as 6/7 speed.

6/7/8/9 speed mechs are interchangeable IME, sounds like something else is at fault.

Not sure if the chain would impair shifting, but it may cause some issues, 7 & 8 are interchangeable.

Posted 13 years ago

scaredypants
Full Member

mucky cables, wrong outer length, inner cable clamped wrongly at mech ? ?

Posted 13 years ago