It's because the tiny engine is pretty much useless except for flat courses with a sprint finish. Any mountains and the cyclist have to carry that deadweight al

It's because the tiny engine is pretty much useless except for flat courses with a sprint finish. Any mountains and the cyclist have to carry that deadweight all the way just for it to work for the last minute, and by the end of the climb the cyclist carrying this might as well be gapped because of this weight. Same reason that you see riders jettison their bidons just before a climb in the tour de france.