Rear Cog

[Teamslug]

I have read on the forum that changing the front or rear cog is a good mod and everyone seems to have done it (except me) i fancy changing the rear cog as i have read its less severe than doing the front, what i am after is info what happens if ya put on a 15 tooth on the front or a 43 tooth on the rear? how does it affect the bike does it cut the top speed? how much will the speedo be out?
I know these are simple questions and i should know the answers but i aint that good with a calculator.

My storm currently has high level ART cans, fiddled with standard suspension 15mm fork leg above top yoke and Dunlop 207RRs

[Stormin Ben]

I've changed the rear sprocket by adding another 2 teeth.
Result:-
Punchier off the throtte
Turns easier (shorter wheelbase)
Looks smart
Reduces unsprung weight on the rear

It's not affected the top end noticeably, according to calculations top speed is reduced by 4.9% (43teeth / 41teeth = 1.049 ie 4.9% change)
which equates to 7mph off the top end
Speedo OVER-READS by the same amount ie 0.5mph per 10mph
31.5 = 30
63 = 60
ie bugger all!!

Just do it, you'll not be disappointed

cheers

Ben

[Teamslug]

Cheers and thanks for the info my storm is due a chain and sprockets in the not to distant future so its a 43 tooth rear on the shopping list

Thanks

[Swifty]

On an opposing note...

If the rear sprok were a bit smaller...would that help out fuel mileage. I'm thinking about Long-distance gas mileage and it would only be a temporary job. I only get a max of 120Miles per tank, and that SOOOKS! Obviously, throttle and acceleration would be laggin then, but would this negatively affect any gear/crank. Just tryin to be safe about it before any money spent...and engine go BOOOM...and me go slidy into tree...

Whatcha say?!

[vtr-bad-boy]

i chatted to bloke from FMS who infod me that even going up to 42 on rear would help wheelie etc and not make engine too revvy at high speed. FMS are a great web site and i save £30 on getting new renthal sprokets and a new OSR-7 x-ring chain from demon tweeks prices!!!