A forum for owners of Yamaha TTR250 trail and enduro bikes!

sammyttr · Senior Member

Gearing opinions

TTRfan · Super Guru

Hi Sam

If you were happy with the gearing before then you just need to go down on the rear sprocket in the ratio of 17 to 18. So if it was 44T it should now be 41T or 42T.

What this simplistic calculation doesn't take into account is the different profiles of the tyres. If you were able to measure that it would help.

If you are running 13T on the front sprocket at the moment it might be worth swapping it for a 14T and see what that does?

Brian

sammyttr · Senior Member

Cheers Brian I was running standard gearing which be 14 on front and 44 on rear, I was happy with that, so if go up 15 on front and I'll try 42T on as not too big a drop and if not happy go 41T but think it's front that makes more difference

TTRfan · Super Guru

14/44 would normally give a ratio of 3.14. Going down to 17" rear would mean that goes down to 2.96

15/42 might be a bit OTT Sam as that gives you a ratio of 2.80 on standard wheel going down to 2.64 with 17"

The nearest to 2.96 would be 14/43 which would be 2.90 if my maths is correct!

14/42 would be 2.83.

Have a play here remembering the 17/18ths multiplier.

sammyttr · Senior Member

Cheers Brian my maths is crap I'll keep 14 on and go down on rear instead want it to be able to cruise okay and not over rev too quick in sixth