I just started racing hare scrambles recently. Try dealing with arm pump for 1 1/2 hours. It's not fun at all. I've learned that foremost I need to stay relaxed. Also the tip about holding the bike with your legs more is right on as well. I have nasty scrapes on the insides of my knees from this last weekends race. As others have said, you have to ride quite a bit to alleviate arm pump which translates into becoming more loose and comfortable on the bike. Staying hydrated is very important and I've also been told that taking potassium supplements or eating a banana helps to keep your muscles from building up lactic acids(creating arm pump). Hope this summarizes
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