Front wheel speed and rear wheel speeds are similar when coasting. That is a constant with every tire that we've seen. If you are watching a dyno run and you see smoke coming off the rear wheel, that is slippage and the dyno is incapable of accurate information at that power level. It's worse to have an inconsistently accurate speedo than a consistently inaccurate speedo. BC700 bicycle speedos, mounted on the front wheel, properly calibrated, are very accurate.
All japanese tachs read high.
The error is generally NOT consistent. The stock gsxr tachometer has a relatively constant error rate in comparison. It makes some difference as to how they are mounted, but there is no reliable mount for race motorcycle use. A smaller error below 6100 rpm and magically at 6200 rpm, they change to another, more optimistic error rate. Register for Factory Pro Tuning email updates 1.