Is this allowed for SVA?

It will record accumulated milage and is back lit.

only issue i can see is that it will not work on the speedo test on the rollers!

Never mind the rollertest they don't work indoors anyway.

Fit a Halfords/Cat eye whatever bike speedo for a couple of quid. and then have the GPS to double up and confirm the higher speeds.

Andrew

I agree with Andrew, the GPS makes speedo calibration easy, but not allowed on its own.

Marcus