changing sprockets makes speedometer invalid?

[Jo Rhett]

I have repeatedly seen comments on here about different sprockets and how the odometer is inaccurate.  I'm confused.  The sensor is on the front wheel -- how would running different sprockets change the validity of the odometer?  Or am I confusing this with changing front wheels?

Reason I'm asking is that I need to replace the sprockets & chain on my street bike.  I have a whole 520 kit with a 45 rear sprocket sitting here.  Is going from a 44 stock to a 45 rear going to affect my speedometer accuracy?  I'd rather not, as I currently live in Sunnyvale where cops are *BORED* and are known for giving tickets for 5mph over.

Yes I know the speedometer is "optimistic" at best.  I've done a lot of testing and it appears to be consistently 10% high -- so 44mph reported is 40mph, 66mph reported is 60mph, etc.  I'm very used to that.

-- 
Jo Rhett /  velociRaptor Racing
#553 WERA