Don't they! ;)

You'll hear all kinds of stories. In reality, both will likely help your cycling (and PC's your running) when used as a training tool, since they will cause your muscles to work differently. But whether or not you can/should race on them and how much of a gain you will realize, there is no hard and fast answer.

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"Non est ad astra mollis e terris via." - Seneca | rappstar.com | FB - Rappstar Racing | IG - @jordanrapp