| Lily, never used a bike mounted lap timer but I am sure they can be useful. Always had someone stand on pit wall for hand measured lap times.
For racing, you'll need a TranX260 transponder. It will vary from club to club but DP, Bemsee, and NewEra use them. With DP, you can hire one for a tenner if you only do the odd race. For a full season you need to buy one anout £200. | 
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