How to Fit Women's Mont Blanc Carbon for Trail Racing

Quick answer

Start with your usual Altra size, then fine-tune the fit with a heel-lock lace pattern and thin, low-friction socks to prevent blisters during fast trail efforts.

Step-by-step fitting guide

1. Size up for toe splay: Start with your usual Altra size. Check for a thumb's width of space from your longest toe to the front of the shoe. Altra's FootShape™ toe box allows natural splay, but your toes should not touch the end on downhills. A too-small shoe can cause black toenails on long descents.
2. Secure the heel with a runner's knot: Use the extra lace hole near the top of the collar. Thread each lace end down through that hole to form a loop, then cross the lace through the opposite loop before tying. This locks the heel in place without overtightening the forefoot. If your heel lifts during a test jog, re-tie with the runner's knot before considering a half-size down.
3. Choose thin, low-friction socks: Wear socks that are 1–2 mm thick and made of synthetic or merino wool blends. Avoid thick cushioned socks that add bulk inside the shoe, which can cause pressure points under the carbon plate. Test the fit with the exact socks you plan to race in.
4. Walk and jog on a slight incline: Simulate a short downhill and a few strides on flat ground. Your foot should not slide forward, and the arch area should feel snug but not pinched. If you feel the plate edge under the ball of your foot, the shoe may be too long or the laces too loose. Pain under the arch or a hot spot after 2 minutes means the fit needs adjustment.

Product facts

• Women's Mont Blanc Carbon: The Mont Blanc Carbon features a full-length Carbitex™ Monoflex carbon plate for extra propulsion. A snug midfoot hold helps you transfer power efficiently through the plate, especially on climbs and accelerations.