I would like to replace my 7 speed HG70 cassette and chain. My problem is that it is increasingly difficult to find quality parts for 7 speed system.

My bike is a Trek 970 from 1993, originally with Deore XT / DX system.

Last time I changed I could bought a 7 speed HG70 12-28 cassette and a HG70 chain, but now these are super rare and are only possible to find on eBay for NOS prices.

What I would like to ask is that what are the exact steps and parts I need to change if I would like to upgrade for an 8 of 9 system, as mentioned by Sheldon Brown? Other than buying a 9 speed cassette, a 9 speed chain and a 9 speed rear shifter, what do I need to buy or fix?

2 Answers 2


You don't need to buy NOS. 7 speed cassettes are still manufactured, we stock them and they start at $20 all the way up to $36 for a Shimano HG50 which comes in 12-28. Go with a matching Shimano HG50 chain.

Unless you buy a new rear wheel, you cannot go above 7 speed. 7 speed freehub bodies are shorter than 8+ speed freehub bodies. An 8+ speed cassette is too wide to fit your freehub.


Nashbar has sram 7 speed cassettes under $20 their part#is SR-PG730.They aren't the best they ever made but at the price you could buy two.I would splurge and get a new chain so you won't ruin your new cassette.Take all the money you were going to spend on up grades and save it towards a new bike or a later model used bike when this cassette wears out in 2000 miles.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.