Same problem here (old age may have something to do with my problem) however, make sure your gloves are not strapped on too tight - found that to be a problem. Also, once the numbness starts pump your arm - it will speed up the blood flow to your hand. Usually 4 or 5 pumps, while flexing your fingers, should get rid of the numbness.
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LeMond Zurich(2003), Winwood Carbon Post, Fizik Arione Saddle, Speed Play X-2 pedals, 3T More Carbon Bar & Giant Carbon Stem, FSA Super Light 53/39 Crank Set.