Jump bike components

OllieTheWelder

Hi, I have got myself an old mountain bike that I am halfway through converting into a jump bike. I don't know what I will need to do this though. I am struggling on rear cassette and sprocket? Also are sprockets universal and does it matter what sprocket I use? Lastly, what rear cassette do I need?

Thanks, Ollie.

cooldad

Depends on the crankset and back wheel/what speed it was originally.

OllieTheWelder

I'm planning on buying buying new sprockets for both the cranks and the back wheel. I ideally want something like a 25t front sprocket so would something like a 12t rear be good or would you recommend something else? The wheels are 26".

Ollie.

cooldad

Still depends on the crankset (ie what chainwheel will fit the spider) and rear wheel (freehub, screw on)
But if you want 50% ratio, I would go for bigger (17/34 or something).