Hi all,
So I’m doing a flat road century on my CX bike in a month. Right now my bike has a 9 speed SRAM X-9 rear derailleur, chain, cassette and knobby tires. Can I borrow a roadie friends 10 speed wheelset and have things semi-work? I figure I might not be able to use the largest ring in the back but will things play nicely?

Don’t be daft, just change the tyres

you might get 4 gears to work.

gotta be worth it?

Just do it on the knobblies. I have, and didn’t die.

Just change your tyres, why cock about?

Depends on what your top gear is up front. You will need a 50(ish) ring for the road I would of thought.

Even minor gear niggles become really annoying.
Don’t do it.

No it won’t. Do it on knobblies, or get some slicks.

Could he not just pop the 9 speed cassette onto the other wheel?

Yep. That’d work.

do this!!

Could he not just pop the 9 speed cassette onto the other wheel?

nine speed shifter WILL NOT WORK with 10 speed cassette. you can borrow the wheels and switch the cassettes though, as above.

bear in mind you may still need to tweak the gears, and there’s a good chance you’ll need to adjust the brakes too. why not just stick road tyres on? less time needed, not that expensive. depends if you’re going to do much on road.

Just borrow your friend’s tyres?

Borrow your friends bike

make your friend do it for you?

By the time you’ve faffed around making the decision you could have ridden the century.

it depends if your in a hurry/trying to keep up with someone faster.
if you’re not, dont bother changing anything, you’ll be fine.
if you are, change the tyres for some thing more road oriented.
knobbly tyres will be fine, but it will take a bit longer.
hope the weather gods smile on you.