Oohthats a tricky one. Nearly all high-top mountain-bike shoes that Im aware of are winter-oriented shoes. That would include the Lake MXZ ($250; www.lakecycling.com) and the Sidi Storm 3 ($230; www.sidiusa.com). But, as you say, thats not what you want. Those shoes are awfully warm, and not suitable for summer riding. Lake also makes a sort of three-quarter-height shoe called the MX 265 ($160), which is billed as a three-season." But it has some insulation (Outlast temperature-regulating material), so if youre after a summer shoe, it might still be too warm.
In any event, even a full-height mountain-bike shoe is not going to really stabilize a severely sprained ankle. So what to do? I think the path to take is to get yourself a good ankle stabilizer. Not a stretchy ankle wrap; that wont do any good. Ankle stabilizers are made of non-stretchy material (usually something like Cordura) that wrap around the ankle, lace up, and provide nearly bomb-proof support while fitting under nearly any shoe. I know of what I speak as Ive had to add some ankle support to my right ankle for a number of years. When I wear the brace and go hiking, I eliminate roll-overs or additional sprains. When I dont wear it, well, Im usually sorry.
There are several models available. One of the better ones is the Swede-O Ankle Lok ($35; www.swedeo.com), a lace-up model with internal steel stays for extra support and an elastic back so your Achilles tendon can move a little. The Core PowerWrap ($45; www.coreproducts.com) is another good-quality wrap, with features similar to the Swede-O model. The key is that these things MUST lace up. The ones that use hook-and-loop straps just arent strong enough.
Ankle sprains are nasty. Theyre often dismissed as minor injuries and the victim told to walk it off." You might see an orthopedic doctor or sports-injury specialist. He or she can recommend exercises to help strengthen and stabilize the joint. You also can pick up a good ankle wrap from the office, and get advice on lacing and use.
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