On my 2015 Streetbob replacing the speedmeter. I know the new one will pull the mileage up from the ecm. If I decide to revert for whatever reason will my original speedo catch up on the new mileage? I ask my Dyna brothers first before really digging into this sight.

 

I’m no expert and really can’t say for sure but since the speedo draws info from the ECM I would say yes it will.
That’s my opinion, so that and a couple dollars will buy you a shitty cup of coffee. 🙂

 

Yes, on the electronic speedo's the milage is pulled from the ECM. Where that one was already married to your VIN it will simply update. I did this on my '14 SGS. I "upgraded" to a set of Dakota gauges, hated them and couldn't get used to them, reverted back and the milage updated. If I recall correctly, it was on a key cycle after the 1st ride.