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[Thack]

Simon: OK, that sounds like it did the job. The reason for tweaking the length of the spiral hairspring is that it can remove that effect where it's fast at one end and slow at the other. Or at least it will help you approach that. Whether it's worth bothering is another question, of course!



zippy: "the sign said "Give way" Then the speedo needle fell off ......." LOL! I've never driven a Ural, but I bet they are immensely characterful. My front tyre only has 1000 miles on it, like the rest of the bike, so it's probably OK.

[MartinB]

I have no scientific proof but my gut feeling after 40 years of riding tells me my Electra was and my EFI Bullet speedos are definitely optimistic by at least 10% quite possibly even more.

[simon]

Yes no question that hairspring adjustment would be a useful method of calibration but the thing is these magnetic speedos aren't really designed to be touched and so the hairspring is in the case of the Veglias anyway spot welded in place. Also there is no way they are very going to be really accurate right across the range as the temperature and the humidity will have an affect as with every other variable including as mentioned the state of tyre wear. However the accuracy can be set within reasonable tolerances and certainly be closer that 10 mph particularly at normal road speeds.