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 Post subject: Cog spacings?
PostPosted: Wed Jan 30, 2019 8:08 pm 
Devout Dirtbag
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Joined: Sat Dec 22, 2012 7:49 pm
Posts: 105
Location: London UK
Is cog spacing standard for a given number of speeds? I always assumed the shifter and mech needed to be matched as the geometry differed between brands but to achieve the same lateral movement. Are rear cogs interchangeable so long as the rest of your setup is for the same number of gears?


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 Post subject: Re: Cog spacings?
PostPosted: Wed Jan 30, 2019 8:10 pm 
B.o.T.M. Winner / Feature Bike
B.o.T.M. Winner / Feature Bike
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Joined: Tue Dec 13, 2005 3:26 pm
Posts: 6377
Location: Tilting at windmills and shouting at the rain.
This is the reference page for this:

https://www.cyclinguk.org/cyclists-libr ... s/shimergo

Tells you what goes with what, along with spacing etc


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 Post subject: Re: Cog spacings?
PostPosted: Wed Jan 30, 2019 8:13 pm 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 9552
Location: New Forest, UK
Cog spacings for SRAM and Shimano:
6+7: 5.0mm (also Campag 8 speed)
8: 4.8mm
9: 4.35mm
10: 3.95mm.

Up to 9 speed cog thicknesses were the same, after that they got thinner.
So you can shuffle cogs between speeds pretty effectively. From 10 speed onwards it all gets more finicky.


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 Post subject: Re:
PostPosted: Wed Jan 30, 2019 8:22 pm 
Devout Dirtbag
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Joined: Sat Dec 22, 2012 7:49 pm
Posts: 105
Location: London UK
Brilliant. It's a 7 speed setup i'm tinkering with and i'm never more than 9 speeds so i should be good. Thanks!


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 Post subject: Re:
PostPosted: Wed Jan 30, 2019 9:51 pm 
Retro Guru

Joined: Sat Oct 10, 2009 12:31 pm
Posts: 324
Shimano rear mechs work with any indexed Hyperglide setup from 6-10 speed as long as you have the right shifter for the block or cassette. Basically, just buy a 10 speed mech if in doubt, since they are backwards compatible. (there are very few exceptions to this rule and they all involve Dura-Ace).

Then they changed it for 11 speed :evil:


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 Post subject: Re:
PostPosted: Wed Jan 30, 2019 11:23 pm 
Retro Guru
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Joined: Thu Jun 23, 2011 11:25 pm
Posts: 2220
Location: It's not easy being a dolphin.
I'm compelled to comment. I've recently arsed about with a SRAM 7 speed cassette to work on 8 speed Shimano indexing. It's
an old 1995-ish SRAM cassette for some 7 speed Gripshit lever and the cog thickness was way more than St Sheldon
described. So much so, the original spacer thickness was actually closer to normal 8 speed.

I ended up using 9 speed spacers with the 7 speed cogs for it to shift perfect with a 8 speed chain and with 8 speed
Shimano shifters. I won't even go into the faff of finding spacers so the cassette lock-ring didn't bottom out first. Arguably
it was the biggest arse and faff I've had in this domain, and I've normally done all sorts of mix and matching but this was
the cat among the pigeons that threw me off completely.

Bizarre, yes, but a vernier caliper doesn't lie. My advice would be to measure your set-up to see if it really does
fit the assumed and publicised specs. especially the overall cassette width. Good luck hacking :wink:


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 Post subject: Re: Re:
PostPosted: Thu Jan 31, 2019 2:04 am 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 9552
Location: New Forest, UK
rogerzilla wrote:
Shimano rear mechs work with any indexed Hyperglide setup from 6-10 speed as long as you have the right shifter for the block or cassette. Basically, just buy a 10 speed mech if in doubt, since they are backwards compatible. (there are very few exceptions to this rule and they all involve Dura-Ace).

Then they changed it for 11 speed :evil:


10 speed Shimano went to a different cable pull for MTB. Only road 10-speed mechs have the same ratio as 7/8/9. Even then, there is now a wierdo Tiagra which is 10 speed but runs on the 11 speed road pull ratio.


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