Only just read the op about double brakes. No chance for me on my track bike - are any of the downhills worse than, say the north/south downs?
If you are fixed, you have effectively two brakes. Give yourself plenty of room fore and aft, stay alert, control the speed, and it will be fine.
@Bernie started
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If you are fixed, you have effectively two brakes. Give yourself plenty of room fore and aft, stay alert, control the speed, and it will be fine.