At present I am running stock sprockets 13/52 (4.00 ratio). I want to slow the bike down for more woods/trail putting around riding--sort of be able to lug it like a tractor for blazing trails and checking out new areas--mostly 1st and 2nd gear stuff in tight, whitetail deer woods with logs and some mud. I am thinking of going to 12/54 (4.50) or 12/54 (4.15). I would not have to legthen the chain if I go 12/52 (4.33) but would this be slow enough? Would the 12/54 or 13/54 be too "snappy" and tend to wheely too much and/or top out too soon?

I discovered when I mounted a 54 rear (13 front) I needed a longer chain but at the time I did not want to take the stock chain off and mess with another trip and order a new one. Is there an easy and inexpensive way to add additional links? Also, do I need to modify anything running a bigger, 54 tooth rear sprocket, such as the chain guide?

Anyone know the math necessary to compute what the above ratio changes would do to top speed? I chickened out at 80mph on my computer (RR bed trail) with stock gearing/sprockets. (it was still pulling!) If the bike will cruise 50-60mph comfortably (say 7000-9000 rpm) with a 4.50 ratio, I would be happy. I know the bike revs to 13000+ but I can't ride it that way! No time to enjoy the sceenery--it's just a blur!

I think what ratio works best for you is a matter of trial and error. Unfortunatly that can get expensive. I do mostly casual track riding and on groomed trails. I find the stock gearing good for the trails and switch to 12/49 or 12/50 when riding tracks (so I don't have to change the chain). I found 12/52 and 12/51 too low for my style of riding even on tight tracks. When I need a new chain I will likley go with 13/53 (same ratio as 12/49).

I don't know of a reliable way to add links. You may have to modify the chain guide for a 54 but not too much by increasing the length or depth of the rear opening and trimming the chain block. I have a carbon fiber guide so it is easy to file down. Never tried on the stock aluminum.

Here is a recent thread with a speed calculator for different gearings: Sprocket(Gearing) choice?