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K2 Radical 90 or 100 or Other Inline Skates, Plus Wheel Size and Frame Placement Tips, Blisters, Pain, Pronation, Supination

roadskater's picture

Someone on a semi-private internet email list (is there such a thing?) asked a question I thought was well-asked, and I wanted to answer it for them, and for everyone out there who might be thinking about inline skating but doesn't know what to think about all the choices.

Here are the main points of the question, or the ones I wanted to address...

  • I skate K2 fitness skates
  • I'm considering K2 Radical 90 or 100
  • I'm not interested in low-cut speed boots
  • I get ankle blisters and part of the boot digs in to my calf on the outer side
  • I've tried various frame placements (/ \ V-in, \ / V-out, | | straight) but my left anke bends in

This person was considering K2 Radical 90 2009 and K2 Radical 100 2009 models, but this information applies to most skates.

For starters, if you want to skate, get some good skates if you can afford it. Consider what you pay for your sweetest tennis/court/running shoes and maybe you'd want to spend at least that much for shoes with wheels on them. I recommend 84mm wheel size and up for skating on the roads, mostly in a straight line and around normal street turns, but I regularly get outskated by people with smaller wheels in my park and in the cities we visit for skating festivals. That's for what I call "roadskating." If you do "street" or "vert," you probably already know to look for smaller wheels and frames and maybe a grind plate and such.

You can start roadskating on skates from 76mm and up easily, but the advantage to 90mm and 100mm and up wheel sizes is they'll roll more easily over poor street surfaces and other gunk that comes along (or is sitting there as you're skating along). Read on for more on the differences in wheel size and frame length. Here's what I wrote, edited slightly.

First, if you get K2 Radical 100s you could still put 90mm wheels on later (but not the other way around of course, unless you replace the frame later, which is not hard to do but can be expensive). The main difference you'd feel would be frame length. If you like to do twisty curvy moves, go with the 90s or models with even smaller wheels and less space between the wheels (this frame will take curves more easily without doing crossovers, and will let you carve arcs more easily on one foot).

If you want to have straight line stability, go with 100s, because of the longer frame. In general, a longer frame will feel more stable at high speeds, like going down Silver Hill during Athens to Atlanta, or going down the fast hill to the dam after climbing Stonewall Jackson at Georgia Stone Mountain Park (counterclockwise from above). I can attest that 5x84 feels more stable in the 40+mph range than 3x100+84, but I think this is due to the fact that the 5x84 is a longer frame, not due to the wheel size. 4x100 might very well feel a bit more stable than the 4x90, then, due to frame length, and might even feel a bit more stable even with the same frame length.

As for wheel size, faster or longer (or both) roadskating seems to favor bigger wheels, since they may spin up slower but once going they have more momentum. Still, indoor skaters seem to be going big wheel all around so the spinup must be a small issue.

For roadskating, if you skate over railway tracks or imperfect asphalt often, the larger wheels will go over rough spots more easily, and the longer frame will bridge over these imperfections noticeably better. On the streets of Philly or Manhattan, even DC and Miami's South Beach, bigger wheels are going to feel sweet when travelling, though smaller whells and shorter frames will be the best for dancing in the parks...but I've seen some amazing get downs on big wheels from folks with strong muscles, bones, boots and frames.

The jury is still out in my mind as to hill climbing on bigger versus smaller wheels. I think climbing is better with smaller ones, but am not sure of my positon on this. Anyone have thoughts on hill climbing and wheel size?

As for frame height, I don't know if the K2 Radical 100 frame is a higher frame than the 90 frame, but if it is, this would require some extra ankle strength to control it, too. Does anyone know about the frame lengths and heights? (The K2 site only mentioned the 100mm frame length, and for the Radical 90, their photo shows the 100 frame on the boot!) Most people like the lowest frame they can get that is the length they want and holds the size wheels they prefer.

As for blisters and bent ankles, the bad news is that lots of times (not all, by any means) it's our way of skating or putting on our skates or adjusting them that cause some problems.

Huh? Me? Yes. Me. You. Many of us. For example, when you are not pushing with your heel, but are pushing with your toes and ankles, this works OK if not the best for skating, but will tend to make your heel go up and down and up and down and so on and so on, causing a blister. This is not the only way you can get blisters, but it's one. (Another is when you have carbon fiber boots that are not yet heat molded to your feet.)

Bent ankles, or pronation and supination, can cause boots to cut in on one side or another or both, and the bent and not bent repetition can burn a blister into your skin too. [If you're used to speed boots or even low fitness boots and go back to full height rec skates for a weekend of city skating, this can rub your shins badly too.]

Fortunately, most recent recreational and fitness skates, especially those with the 90mm and 100mm and up aluminum frames, can be adjusted by loosening the mounting bolts (usually two), adjusting the frame positioning, and retightening them. As the questioner mentioned, the some advise others to V them in, V them out, or line them up straight.

Better common advice is to set the front of the frames to center on the gap between your largest and second toe, and to position the back of the frame to the middle of your heel. Sometimes you can't even feel where your foot is of course, but the key is balance.

I think the best way to set your boots and frames is so you can stand on them and be balanced on a road or on some shag carpet even (with wheels on, but on carpet you could do this without wheels on). You should be able to stand around at the Miami Great Esskate or Philly Free Skate and wait for the slower ones to come along without wanting to die from the sideways forces on your ankles and toes. If you can't stand around balanced on your skates not moving, you'll likely have some moving and bending of ankles and toes and some rubbing skin when skating.

For very short indoor races this might not be the case. I've been around guys who hate their skates except for the 45 seconds it takes to win their event, but they're happy to have the trophies! Other roadskaters who are faster and more gifted than me may have different views, but for long distance roadskating at least, I think

  • balance is the key to a more
  • direct leg-powered push (as opposed to an ankle-flick and toe-bending powered one) and an
  • efficient glide
  • spending more time on one skate instead of two
  • without all your balancing muscles in your shins and feet working overtime, and thus to
  • long happy hours of endurance.
  • [Meaningless bullets added for emphasis and for those who won't read this whole thing!]

In my case, I have to set the two boots up differently. Since i am perfect this must be a lack of symmetry in the manufacture of the boots, quite possibly the positioning of the boot's frame mounts, which are often amazingly ill made considering the loads they'll take. When I set up the boots so that I can balance easily while standing around, it makes gliding on them much easier.

So to repeat a bit, I'd

  • set the front frame position between the first (biggest) and second toe and
  • in the back in the center of the heel portion of the boot (I actually do this by feeling whether the frame located is in the middle of the heel portion of the skate to start with).
  • Stand on the skates (maybe not even buckled or laced tightly if you can do that without hurting yourself).
  • If your ankle is bending in, move the back of the skate in the direction the ankle is bending until you can stand still without it bending in. The goal is to be balanced on the back of the skate frame when standing without having to cock your ankle in or out when standing, first, then when skating.
  • If you feel extra pressure on your big toe, you might consider moving the front outward a bit, and move it the other way if your smaller toes are working overtime.
  • Ultimately you want to be able to lift your toes while keeping the ball of your foot down and still feel balanced at the front of the skate, so the balance point is really the ball of the foot, not the toes.

If you're careful and fairly stable, you could do this balancing and frame movement with the frames just loose enough to be able to move them, but of course, don't do any skating like that.

Once you get it all right, you're not finished! Another important thing is to

  • photograph your setup front and back with both boots or
  • mark the centerlines of your setup on the front and back onto your boot with a Sharpie or some other method.
  • Consider using some Loc-tite blue (not the permanant stuff) on the threads if you're worried about the bolts vibrating loose.

Ideally, I have a mark on the front of the boot that I can view while in a tuck or just goofing along. The front or back of the frame can move without me noticing without these marks, and I can really think I am just not good that day, which is often true, but sometimes it's just that my frame has moved.

Hope this helps. Skateylove, roadskater


Silver Hill Road
Stone Mountain, Georgia
United States
33° 49' 30.9576" N, 84° 9' 52.3944" W
Stonewall Jacson Drive Stone Mountain, Georgia
United States
33° 47' 43.5444" N, 84° 7' 56.4456" W
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