I ran across a binary encoder at work, and noted that it has the ability to determine rotation. Like a JO counter, you could back up with this type of counter.
Disks are available that will fit a bike wheel. All that's necessary is a circuit board that powers the encoder and provides a readout. The readout could be mounted to your handlebars.
You can have anywhere from 64 to 2500 counts per revolution. I think 100 is sufficient.
Pricing for the encoder and disk is less than the Veeder-Root counters currently used. Pricing for the circuit board and display remains to be seen.
If there is sufficient interest, I will pursue this design. I plan to build a prototype regardless and put it in the hands of an experienced measurer, but it could be a while before it happens.