7 speed to 8 speed

J

john the sparky

Retro Guru
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you can call me dumb.... :roll:

but is there a shim I need, to be able to run a 7 speed cassette on an 8 speed freehub....

I assume that is the problem, as with the cassette on, there is still movement
:?
thanks
:oops:
John
 
spacerforshimanocassette3888_l.jpg


hope one from sjs

http://www.sjscycles.co.uk/product-Hope ... n-3888.htm
 
Since we're on the subject of 7 -8 speed, I might have a little thread hijack!

Can you replace the bottom two sprockets on an 8 speed cassette with the bottom two sprockets of a 7 speed cassette? The reason being that I have an 8 speed cassette that the two smallest rings are slipping on and a 7 speed cassette that is fine. Since I am no longer using the 7 speed, I would like to butcher it for parts if I can.....will it work? :?
 
The spacing must be the same or else my 7 speed thumbshifters wouldn't work with my 8 speed set up. Hang on I have a new 7 speed cassette and an 8 speed freehub body to hand....
 
BarneyRubble":vf6owk3u said:
Since we're on the subject of 7 -8 speed, I might have a little thread hijack!

Can you replace the bottom two sprockets on an 8 speed cassette with the bottom two sprockets of a 7 speed cassette? The reason being that I have an 8 speed cassette that the two smallest rings are slipping on and a 7 speed cassette that is fine. Since I am no longer using the 7 speed, I would like to butcher it for parts if I can.....will it work? :?
Click to expand...

Mmmm. That was more hassle than I thought. OK, I had a wheel with an 8 freehub on it. The 8 cassette is one of those where the top (bottom) 5 are joined and the smaller sprockets are loose. It all fits together using the relevant 7 spacers. It may be my imagination though but I think the lockring (I used the :cool: didn't need as many turns to do it up? I haven't got a decent camera but I have taken a couple of pics so you can get some other opinions. (I have included Garfield because he has been on my wheel for so many years).
 

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From sheldons site

C-to-c Spacing - Sprocket Thickness - Spacer Thickness

Shimano HG
7-speed 5.0 mm 1.85 mm 3.15 mm

Shimano IG
7-speed 5.0 mm 2.35 mm 2.65 mm

Shimano
8-speed 4.8 mm 1.8 mm 3.0 mm

Shimano
9-speed 4.34 mm 1.78 mm 2.56 mm

as seen above there is only a fifth of a mm difference between 7 and 8 speed so when carefully set up the slop in the system will allow a 8 speed shifter to correctly index on a 7 speed cassette.
 
Thanks for the speedy replies :)

prof farnsworth":32qepaon said:
From sheldons site

C-to-c Spacing - Sprocket Thickness - Spacer Thickness

Shimano HG
7-speed 5.0 mm 1.85 mm 3.15 mm

Shimano IG
7-speed 5.0 mm 2.35 mm 2.65 mm

Shimano
8-speed 4.8 mm 1.8 mm 3.0 mm

Shimano
9-speed 4.34 mm 1.78 mm 2.56 mm

as seen above there is only a fifth of a mm difference between 7 and 8 speed so when carefully set up the slop in the system will allow a 8 speed shifter to correctly index on a 7 speed cassette.
Click to expand...

Am I right in thinking that you can't mix them then? Since they are different widths? Or as the spacers are thicker on the 8-speed, will it make up for the thinner sprockets? :?
 
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