As many of you know, I do bike fits at Cycle Science, and one of the most tricky things to get even close to right on is saddles. Cutout or no cutout, size of cutout, pressure relief, softness etc ... very tricky, and mostly trial and error - it's slow and often a frustrating process.

One of the key variables is width - convention suggests that your weight should be mostly carried by your sit bones - your ischial tuberosities I believe is the proper name for them.  Other research suggests carrying weight on your pubic rami (stradle bones). And, everyone is, of course, different.  If a saddle is too narrow, you feel like you're sitting on a knife, too broad and your soft tissue carries too much weight and you ruin your weekend's fun. So how do you find the bones and measure them to get a reasonable first guess?  You can get a rider and poke into their backside and use a ruler to measure the width, but that's a little .. personal .. for most to want to accomodate.  You can get an X ray, but that's not something we'd usually do in a bike shop.

How else can it be done?  Trek came up with a pretty nifty idea.  We're calling it the arse-o-meter, but I think they have a proper name for  it.  It's a stool (medical practitioners can stop sniggering now please), with a deformable foam pad and a colour-coded graduation for widths. Sit on it, upright, and your sitbones leave a distinct impression in the foam.  Locate the middle of the impressions, get the colour-code, and you have the width. It takes about 30 seconds to do and requires no poking and prodding or guesswork.  When you're done, we just smooth the foam (it's like a cream, really) back so it's ready for the next bum.  It's colour coded so we can say "ahha, a 'blue'" not "a large", as some might not take too kindly to being told they have a wide set of sitbones. Some people get quite touchy about such things.  The Seat of Power .. embrace it .. that's my philosophy, but not everyone is on the same page.

My appologies for the cluttered photos, but the photos tell a better story than I can describe it.

So anyway, how does this help?  It lets us know roughly where to start with saddle widths. It doesn't solve the cutout or no, or how big a cutout question, or padding, but it does tell us, quickly and easily, how wide a rider's sit bones are.  This isn't just useful for checking against the new Bontrager InForm saddles (which are very good, I have to say, I was quite surprised), but also other manufacturers.  Hopefully we'll get one in at the shop, I think it'll be a useful tool as part of a fitting, and will take out some guesswork.