My thumbs also get cold. The only relief I`ve found is being able to pop the thumbs out of gloves, and have them join the of the hand. Luckily my gloves are rather loose fitting. I only do it when I know the next strch of riding will not require any abrupt need to use them. Like a quiet stretch in a park or quiet street with no traffic, people, or need to slam on my brakes.
Maybe those smaller Toe Warmers might fit in the glove area? Or how about those rubber things that go over the thumb for for a better grip when paging papers?
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