I ran my CRF250x on the lanes around me over Easter for further than I normally do. I know its geared for off road but as I use it for mostly off with a bit of on road I am thinking of changing the rear sprocket. I am right in thinking, it's been a while and the old grey matter isn't what it used to be, that for every tooth down on the rear sprocket it will reduce torque by about 2% and increase speed by the same amount. ? It's running a 53 tooth at the moment and whilst it is great for popping the front with every gear change its far to low for more then a mile or two on Tarmac. Thank you in advance.
Unfortunately its not that easy to work out as you have to take into consideration the gear box ratios, size of wheels etc. As a rule: bigger on the rear = faster acceleration and lower top end smaller on the rear = slower acceleration and higher top end Smaller on the front = faster acceleration and lower top end bigger on the front = slower acceleration and higher top end so to work out the ratio divide the rear teeth by the front teeth (assuming a 15t front): 53/15= 3.53 if you want slower acceleration/higher top end then: 52/15= 3.46 https://woodgears.ca/gear/ratio.html
Thanks pal. I will have to whiz the front cover off and have a look, then do the maths. I don't want to lose all the manic fun but on the tarmac its revving it tits off by about 65mph. Not that I want or need a high top speed but lower engine speeds at 40/50 mph would be more relaxing and help anyone within ear shot from developing tinnitus, me included. The Yoshi system sounds great especially on the over run but it's a loud son of bitch.
A lot of guys here run crossers on the moto X track, beach, hill climbs and sprints. They have an extra set of motard wheels for hard surface use with appropriate rear sprocket and tyres. I think you could use a split link chain to make changes easier (you'd need less links for smaller sprocket). Don't know whether this is any help to you, but at least it gives you options.
