changing the rear cassette

[Shropshire65LW]

I have some 10 speed shifters and a 10 speed Derailleur, that I want to fit to a mountain bike , which currently has a 8 speed cassette , to change this is there anything I need to be aware of , are they universal fitting …...

 

[vickster]

I have some 10 speed shifters and a 10 speed Derailleur, that I want to fit to a mountain bike , which currently has a 8 speed cassette , to change this is there anything I need to be aware of , are they universal fitting …...

You need to do both front and rear derailleurs and chain.
On the rear mech, you need to make sure it can handle the cassette.
You should replace the gear cables too
You’ll need to play with spacers on the wheel too, assuming it can take a 10 speed cassette

 

[Cycleops]

Your existing freehub may not be able to handle a 10 speeed cassette. Remove the existing cassette and measure the freehub, if it’s 35mm you’ll be okay. If you find a spacer at the back of your cassette you’ll probably also be fine. You’ll need a new wheel or freehub if you don’t have the width.
You’ll also need New chain and derailleur. FD will likely be okay.

 

[GilesM]

The Ten speed chain should work okay with the 8 speed chain rings, although it might not be perfect, and if the chain rings are worn, then it will definitely be very rough with a new chain and old worn chain rings, you could try it, but be aware you may need to change the rings as well.

 

[Ajax Bay]

You may not need to change the front mech. Try the 'new' LH shifter on it.
The current 8sp rear derailleur will work with the 'new' 10sp RH shifter. Try it.
Current cables should be fine provided the end is not frayed (and has been cut shortish). New cables cheap though.
The OP's wheel has a freehub for an 8sp cassette so a 10sp cassette will fit.
A new 10sp cassette will require a new 10sp chain.
A reasonable rule of thumb is that chainrings are fine one speed removed - 8sp > 10sp is two speeds removed. Front shifting may not be as smooth as a result.
Overall benefit: slightly shorter step between each gear and 10 speed bragging rights.

 

[Shropshire65LW]

Thank you for your replies , I’ve 2 ways to deal with this , I already have 10 spread shifters and bars ,hence thinking of going down this route, however it’s looking like it may be easier to buy new 8 speed shifters , it’s a old rear Derailleur so I may need to replace that if I can’t get shifters to match . It’s a old Integrated maybe 90s so a new Derailleur and matching 8 speed shifter maybe easier .

 

[Ajax Bay]

Second hand 8sp 'trigger' shifters (flat bar) will be inexpensive. A lot less than 10 speed complications. Derailleurs go on forever if they aren't damaged: they don't really do 'old' and all (OK very very nearly all) will operate fine with 8sp shifters of any SIS age (ie last 25 years).
Choice will depend on whether you want an integrated brake or not.

 

[Gunk]

I went from 9 to 10 on my MTB a couple of years ago (purely for vanity!) I changed the rear mech, but against the advice of my LBS I kept the original XTR front mech and it's been fine.