I have 02' VFR and went -1 on the front sprocket, so its now @ 15 teeth. I left the rear sprocket in stock form. Now that I have one less tooth upfront do I need to shorten the chain? My current chain is stretched to the max so I will be installing 15 tooth sprocket when I install new chain and new rear sprocket. Also how will my speedometer be affected by this? Will I rack up more miles on the odometer or less? or will it not really affect those to much? Thank you..