teeth

[spooky]

i am going to change sprockets on my `trail` GN, front is 16 and rear 41, it seems like there isn`t a bigger rear available off the shelf (still looking though) so looks like changing front is best bet, standard is 15  so would a 13 be too extreme?

[themoudie]

Aye spooky,

If you reduce the number of teeth (diameter) of the front sprocket by that number of teeth you will enhance the wear rate of your chain and front sprocket!   

Might I suggest a return to the 'Standard' 15 tooth front spocket and a 'one off' rear sprocket with more teeth?

If you go to the 'Recommended Services' section of the site and then enter "Sprockets" into the 'Search' window in the top right hand corner of the screen, you should be directed to a posting from 2007, that gives 2 good leads for possible suppliers of 'one off' sprockets!   

I have also found this site selling a 46 tooth sprocket for a Suzuki GN 250: Suzuki_GN250_46t_rear_sprocket I don't know if they are still available, I shall leave all enquiries to you. 

I hope this helps.

My regards, Bill

[spooky]

Intearesting.. however 46t rear will probably mean a new chain as well ? as a mainly off road bike chain wear shouldn`t be a huge problem, but is something i hadn`t considered,  i  will price all of the options then go to gearing commander for a best option i think,, thanks

[SteveC#222]

If you have a manual and know the gear ratios/final drive / revs etc there are numerous online calculators to give you mph/rev/gear figures.

When I reduced my GN's rear tyre from a 5.00 to a 3.50  the standard gearing was way out - reving the nuts of it to hit 55-60 so I changed the front sprocket by one tooth which made a big difference - 3 teeth is a BIG jump on the front.

This place is a few miles down the road from me and use to make one off sprockets for specials - notb sure if they still do or how much they charge.

http://www.bandcexpress.co.uk/shop/transmission/sprockets.htm

[themoudie]

Intearesting.. however 46t rear will probably mean a new chain as well ? as a mainly off road bike chain wear shouldn`t be a huge problem, but is something i hadn`t considered,  i  will price all of the options then go to gearing commander for a best option i think,, thanks

A pleasure, spooky.

My regards, Bill

[spooky]

After a bit of playing with gearing commander i have figured out (i think ! ) that with the tyre fitted (bridgestone trail  120/90) speeds will be at 800rpm in 1st and 5600rpm in 5th with gearing as below

15/41   2,5mph/56.8mph
14/47   2.0mph/45.9mph
15/46   2.2mph/50.2mph

so i might try 13/46, bear in mind this will be for green laning and only local road use,i will try to get sprockets and new chain  from the place bill suggested above , damn the expense, has to be better than getting stuck in the clarts ..

[Ian]

 http://www.jtsprockets.com/catalogue/model/1728

Hi Spooky I have just read this and wondered if the above link will help.
Regards Ian