New casette, or cogs?

[GoatBeard]

A wheel upgrade has been forced upon me. New one comes with an 8 speed freehub, whereas the old wheel was 7 speed. So rather than buy a whole new casette would it be practical instead to just buy an individual cog to take it up to 8 speed? Not sure if that's possible...

 

[Sharky]

What gear levers do you have? Are they indexed or friction? If 7 speed indexed levers, then probably won't work with an 8 speed or would be restricted to just 7.

 

[Darius_Jedburgh]

Are your seat stays sprung to take 8 speed?

 

[Cycleops]

Only £13 at Decathlon:
https://www.decathlon.co.uk/12x32-8-speed-bike-cassette-id_8328485.html

 

[GoatBeard]

8 speed shifter is like £7-8, casette hardly anything more. My god this becomes a cheap hobby if you can DIY it....might as well. What would I be looking at from a shop?

New wheel, remove and refit
New shifters, remove and refit
Casette removal and fitting
Tyre refitting

Parts + Labor + VAT...

 

[Sharky]

Might need a new chain, to go with the new cassette. Also new inner/outer gear cable.

The only tools I can think of would be tyre levers, which you should have and Allen keys + a chain splitter to cut the chain to the same size as the old one.

Will need to reindex the gears, but plenty of videos available on utube.

So go for the DIY.

Good luck

 

[andrew_s]

Just put a spacer on the new wheel before the existing cassette goes on.

View: https://www.amazon.co.uk/Cassette-Spacer-using-Cassettes-Freewheels/dp/B00GJMSLTK

 

[Ajax Bay]

New one comes with an 8 speed freehub, whereas the old wheel was 7 speed. So rather than buy a whole new casette would it be practical instead to just buy an individual cog to take it up to 8 speed?

Share a link to the wheel you've bought, please. Answer to Q2 is 'no'.
Option 1: Use the 7sp cassette with a spacer.
Option 2: Fit an 8sp cassette and replace your RH shifter with an 8sp one. Also new chain for the new cassette (though the old one may be fine if it's had little use - measure it to check elongation: <0.5% should be fine to use).

Are your seat stays sprung to take 8 speed?

Can you elaborate, Darius? What do you think the likely OLN is of the OP's bike rear dropouts (think Carrera Subway): it has a 7sp cassette fitted? Is it likely that an 8sp freehubbed wheel wil have a different OLN? I think the chainstays might have a say in the geometry too.

 

[fossyant]

It's never a cheap hobby. You'll be getting another bike soon

 

[GoatBeard]

Share a link to the wheel you've bought, please. Answer to Q2 is 'no'.
Option 1: Use the 7sp cassette with a spacer.
Option 2: Fit an 8sp cassette and replace your RH shifter with an 8sp one. Also new chain for the new cassette (though the old one may be fine if it's had little use - measure it to check elongation: <0.5% should be fine to use).

Can you elaborate, Darius? What do you think the likely OLN is of the OP's bike rear dropouts (think Carrera Subway): it has a 7sp cassette fitted? Is it likely that an 8sp freehubbed wheel wil have a different OLN? I think the chainstays might have a say in the geometry too.

The wheel in question

https://www.tredz.co.uk/.Tru-Build-...e-Wall-Rim-36H-8-9-Speed-Freehub-QR_19156.htm

Yeah I'll pop a 8 speed RH shifter on. My god I wonder why people bother with bike shops I can change that part faster than I can shave my own....The chain on the other hand is utterly worn, however....it shifts just fine. Still, no point grabbing a new casette and putting an old nasty chain on it. I can't imagine the chain stay geometry would have any bearing on this?

 

[Ajax Bay]

The chain may be "utterly worn" but it's happily mated with the current cassette. Put it on a new cassette and it will skate like Robin Cousins.
My 'chainstay' comment was (merely) in respect to @darius's comment on seatstay 'springing' - but good to be sure that the wheel will fit into your frame which I assume will both be 135mm OLN (MTB entry-level (7/8 speed) norm).

 

[Darius_Jedburgh]

Can you elaborate, Darius? What do you think the likely OLN is of the OP's bike rear dropouts (think Carrera Subway): it has a 7sp cassette fitted? Is it likely that an 8sp freehubbed wheel wil have a different OLN? I think the chainstays might have a say in the geometry too.

Sorry, I don't have an answer. It's just that I thought it might possibly be an issue to check before spending money. It's probably OK but better to be safe than sorry!!!