Ok run down of bike 2001 883 changed from belt to chain drive. 23 front 51 rear but originally had a 55 tooth rear. Now my bike looses speed going uphill and my question is does the change in rear sprocket size going to affect it that much. Keep in mind I was fine with the 55 rear never had a problem with it uphills. Have not changed anything else on bike. Bike and engine both slow down so clutch is not a problem.

 

Smaller rear sprocket will allow the bike to turn at a slower rpm per given speed. You are not as deep in the power band as you once were so she's not making the ponies you once had going up the hill at the same speed as before. Price paid for a more relaxed rpm at cruise.

 

Well the new setup is closer to the stock ratio and I had no problems with...guess I'll have to look at getting a bigger rear sprocket.

 

Stock meaning belt drive 61/27 tooth count.