8 Speed cassettes interchangeable?

[helston90]

I ride an 8 speed setup on my commuter and the cassette/ chain are both gone and skipping around all over the shot (I knew they were going so decided to wear them into the ground),
The cassette is a SRAM PG850 8 speed, do I have to replace it with exactly this?
I have come across a Shimano CS HG 41 which is considerably cheaper on Ribble- would this be compatible with my KMC Z7 8 speed chain which is already in my garage?

 

[Ajax Bay]

No, the Shimano one will be fine and compatible.

 

[raleighnut]

SRAM and Shimano are the same spacing and fit the same freehub, all 8 speed chains are compatible.

 

[fossyant]

SRAM ones are usually a fair bit lighter, if you are a weight weenie.

 

[helston90]

SRAM ones are usually a fair bit lighter, if you are a weight weenie.

Thanks all for your advice, I'll get it ordered- I worry about weight on my best bike but this as this is my commuter I'll chalk it up as extra training.

 

[helston90]

Spent last night building this all up, quick spin around the block, all good, went to commute this morning and the chain was slip sliding everywhere at the front- I've never replaced the chain rings in 7,000 all weather miles and it only came with an FSA Tempo set up on a £500 bike, I take it this needs replacing also? How compatible are 9 speed chain rings with my 8 speed set up? 8 speed road toothed seem hard to come by at a reasonable price.

 

[Blue Hills]

Thanks all for your advice, I'll get it ordered- I worry about weight on my best bike but this as this is my commuter I'll chalk it up as extra training.

I'd relax about weight of components on your best bike as well if I were you. If this is really a concern, clip your toe nails after your pre-ride shower.

 

[Philip51]

I have had my CB Malvern for 10 months now and it's good. Not great, a bit heavy compared to my old Galaxy but very comfortable for commuting. My biggest complaint is the cassette gear spacing. It's a SRAM 8 speed 11-32. The 11 is a complete waste of time for me, coggy and rough. I also hate the big jumps at the bottom. It goes 32-26-21-18-16-14-12-11. I could probably do without the 12 as well so what is a more evenly spaced 32-13 cassette that is compatible?

 

[Nigelnaturist]

@helston90 Chainrings are compatible upto at least 10sp, its the external dimension that change on a chain.
@Philip51 cassettes starting at 13th are not common I don't recall seeing any on an 8sp, a few 7sp have them, and you could use the 7sp one as a starting point with the rest from 8sp or even 9sp cassettes with the correct 8sp spacers. Its easy to make up your own ratios, p.m. if you want to know.

 

[TheDoctor]

Chain Reactions have a 12-32 8 speed Shimano cassette. 12-14-16-18-21-24-28-32T sounds somewhat better then the 11-32T, especially with not having the massive jumps at the lower end.

 

[Philip51]

Chain Reactions have a 12-32 8 speed Shimano cassette. 12-14-16-18-21-24-28-32T sounds somewhat better then the 11-32T, especially with not having the massive jumps at the lower end.

@helston90 Chainrings are compatible upto at least 10sp, its the external dimension that change on a chain.
@Philip51 cassettes starting at 13th are not common I don't recall seeing any on an 8sp, a few 7sp have them, and you could use the 7sp one as a starting point with the rest from 8sp or even 9sp cassettes with the correct 8sp spacers. Its easy to make up your own ratios, p.m. if you want to know.

Thanks to both. I have messed about with cassettes in the past but only to replace worn rings, not change the ratios. Yes, I would like to know how to go about making up a 13 - 32.

 

[Nigelnaturist]

Thanks to both. I have messed about with cassettes in the past but only to replace worn rings, not change the ratios. Yes, I would like to know how to go about making up a 13 - 32.

Rings are usually referred to as chain rings were as cassette rings are referred to as cogs.
Anyway, on shimano 7-9sp the cassettes are held together with rivets, grind the end off the wheel side of the cassette once smooth with the first cog, use a punch to recess it, the cogs can then be removed, be careful with 9sp as the spacers are quite brittle. Use the correct space for the shifter, i.e 8sp spacer for a 8sp, then just chose the largest and work your way down to the lock ring, I found the 12th 7sp work ok with both 7,8 and 9sp set ups. SRAM I believe have a bolt that undoes.

The rivets are just for convenience they are not needed when the cassette is assembled, hope this helps.

 

[Philip51]

Rings are usually referred to as chain rings were as cassette rings are referred to as cogs.
Anyway, on shimano 7-9sp the cassettes are held together with rivets, grind the end off the wheel side of the cassette once smooth with the first cog, use a punch to recess it, the cogs can then be removed, be careful with 9sp as the spacers are quite brittle. Use the correct space for the shifter, i.e 8sp spacer for a 8sp, then just chose the largest and work your way down to the lock ring, I found the 12th 7sp work ok with both 7 and 9sp set ups. SRAM I believe have a bolt that undoes.

The rivets are just for convenience they are not needed when the cassette is assembled, hope this helps.

Brilliant., just what I needed. Thanks. Have to get the Dremel out.

 

[Nigelnaturist]

Brilliant., just what I needed. Thanks. Have to get the Dremel out.

Make up what ever ratios you want, I found a 12-13-14-15-17-19-21-24 with a 26/38/48 front worked quite well

Front rings on top cassette on left, gear inch in table, so you can see with that set up it gives a range of 29-106" 106" is about the same as a 52x13 set up, it also has a fairly close ratio, to get a 29" gear on a 50/34 front setup you would need a 34x32 which gives 28" or so, which considering you would need to start at 12th on the rear the front rear combo would be 50x12 = 110" it would start giving you big gaps in there somewhere.