carbon mountain bike rim
You also need a close fitting (but not too tight) at the heel and toes together with an overall snug feeling around the whole foot. There should not be any 'wiggle room' inside the shoe as this will lead to a loss of power and inefficient foot movement, not to mention the possibility of blisters.
Triathlon Shoe Specifics
You need to be able to get your triathlon shoes on and off quickly. You also need to do this at T1 and T2 during which time you will be hot, fatigued and possibly still wet from the swim. An easy to use fastening system is essential - the normal 'three fastening' system found in road shoes has been proven to be over complicated. Therefore most triathlon shoes use a single, wide fastening Velcro strip. This is a good compromise, offering sufficient stability and security while also easy and quick to use.
