There are: Classic, Sprint and Keep Stuff Out (KSO). (OK, there is also Flow but I don't think it is for runners). Classic are minimal. There is a rubber string you can tighten in the back. My experience with them is that the string can cut into Achilles tendon. I've heard of people cutting and pulling it out. I did and still the way the back was profiled did not agree with my foot. For many people that does not seem to be a problem. Sprint have a strap in the back and on top of the foot. I like those a lot (but also I ordered them a size larger than my Classics that my son now enjoys). I wear them with socks (Injinji) because I've heard that sometimes sand can get under the top strap and makes it feel uncomfortable. Also my feet seem to be prone to blisters. KSO have mesh on top and strap in the back, like Sprints. I would think these would be great for trails but not as cool for your feet as the other models. If you have a store in your area you could try any of those on I would advise doing that. I feel most comfortable in FF one size larger than the Vibram website recommends. Especially when my feet swell that seems to matter a lot.

I hated the Sprints (too tight on my achilles and no amount of fiddling with the straps helped) but love the Classics. I really wish I could have just gone to a store and tried different things on before going through online orders and returning. Look at the Vibram website and you'll see all of the different kinds.

Thanks for the info!  I'm planning to shop the stores next week, but don't expect to find any here...

Do you have REI in your area? Ours carries FF. One can also order them for store pickup with no shipping charges. If they don't fit you just don't pay for them.

FYI:

If you have a City Sports near you they carry the different varieties and will order your size.

 

Not that this is a great deal, but if you sign up on their web site you get 15% off you're first purchase.  This weekend they have a 20% off sale.  Both discounts are for web and in person purchases.  If you go in person be sure to print out the coupon.

 

I bought a pair of KSO w/ the 15% off coupon last month.

I found that after a full summer of barefoot running, my balance was so much better that I didn't have to worry too much about ice.  Of course if you have lots of steep hills, you'll still need the traction.

 Heh, I live in Maine and in the Winter I train on the trails at Bradbury Mountain. 

are those the KSO or the Flow? Be sure to let us know how they work out for you.

I'm wearing my "running" KSOs right now to work - I figure that way I didn't need to bring a separate pair of running shoes tonight.