Road Cycling - Measuring your sit bones?

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View Full Version : Measuring your sit bones?


zanq
04-18-05, 10:01 PM
I did a search or two and while it is mentioned, there really isn't any talk of how to measure the width between one's sit bones. Does anyone have any input, as ridiculous or awkward as it may be?

I just got a road bike, and while I don't want this to become another thread about numbness, discomfort, what do I do, what saddle, etc., I've taken 2 short rides and this saddle is pretty uncomfortable, though I'm not ruling out position and adjustment just yet. I did my own quick and dirty measurement and if this is correct, this saddle may not work for me. I felt around while sitting and found the 2 most prominent points in my butt (ischial tuberosities; aka "sit bones") and measured them twice. My distance is between 100 and 120 mm. Then I measured the widest part of my seat and it is 125 mm, and that includes the wings that taper off. I would say 80 mm is the flat "base" of the saddle.

It doesn't seem right that this saddle is able to press so hard into my soft tissue, but I'm also new to road riding. I have a couple mtn. bikes with saddles that are 145 mm wide and I have no comfort issues at all. If my crude measuring is close to being right, maybe I'll take a look into the Specialized BG saddles.

Thanks!


JimJim
04-18-05, 10:06 PM
Sit bone spacing and shape. Specialized has a fit kit. You can also plop your bottom down in damp sand a few times and measure the sit bone distance and observe the pressure area shape. At home a clear plastic bag filled with a couple cups of flour spread about 1" thick and placed on a hard floor next to a wall can be a sand box substitute. The wall allows you some plop control to mimic "upright" and "bent-over" positions. I made several measurements to get a good average and sketched the basic pressure shapes.

With the multitude of saddles available, why would anyone take even a modest risk on long term sexual problems when a saddle with a male perinal center cut out area can be found that is likely just as comfortable as an old school design.

I cannot tell how comfortable a saddle will be without using it on several long rides while making minor adjustments. I was taught that the saddle height and front-rear slide adjustments should only be made for pedaling biomechanics. The handlebar shape, height, stem, and brake handle positions can be adjusted for comfort, aerodynamics, pressure points, joint pain, etc. Never move the saddle to adjust the upper body position.

Some science and common sense can be used to narrow down the candidates. I currently find the Specialized Avatar the most comfortable. I only considered saddles with perinal cut outs.

Dchiefransom
04-18-05, 11:32 PM
I'm using the Specialized BG Avatar also. It's the best saddle I've had. They use a memory foam that you sit on, on a hard surface, then measure the distance from center-to-center of the depressions. It definitely worked for me.


zanq
04-19-05, 06:12 AM
I cannot tell how comfortable a saddle will be without using it on several long rides while making minor adjustments. I was taught that the saddle height and front-rear slide adjustments should only be made for pedaling biomechanics. The handlebar shape, height, stem, and brake handle positions can be adjusted for comfort, aerodynamics, pressure points, joint pain, etc. Never move the saddle to adjust the upper body position.

From a common sense standpoint, with a saddle that is narrow enough to get in between my sit bones and work it's way toward my colon, I don't think any amount of handlebar/stem adjustments can stop that from happening. My mtb saddles have the cutout (WTB saddles) as well and find them to be very comfy.

I'll try the flour idea! Thanks

Grasschopper
04-19-05, 06:39 AM
When you sit on the Specialized pad they have you sit on it on a chair and then raise your feet onto a box (or similar). This number is NOT the width of the saddle you should get. They take this info and then cross reference it to their chart which takes into account your riding position, a deeper aero position yields a thinner saddle recomendation, more upright is wider.

I did this and got their Avatar saddle in 143mm width and it has been great. Even before I got that saddle I knew the suggestion was going to be pretty close because I had been on a 133mm Selle Italia SLK which hurt and my commuter has a WTB Speed V which is 147mm and is super comfortable for me. I say get a Specialized fitting done (takes 5 min and is free) and then use that info to get your next saddle, be it Specialized or other.

velocipedio
04-19-05, 06:47 AM
get one of those tempra foam mats and sit on it.

zanq
04-19-05, 08:03 AM
When you sit on the Specialized pad they have you sit on it on a chair and then raise your feet onto a box (or similar). This number is NOT the width of the saddle you should get. They take this info and then cross reference it to their chart which takes into account your riding position, a deeper aero position yields a thinner saddle recomendation, more upright is wider.

I did this and got their Avatar saddle in 143mm width and it has been great. Even before I got that saddle I knew the suggestion was going to be pretty close because I had been on a 133mm Selle Italia SLK which hurt and my commuter has a WTB Speed V which is 147mm and is super comfortable for me. I say get a Specialized fitting done (takes 5 min and is free) and then use that info to get your next saddle, be it Specialized or other.

On the Specialized site, they have a chart showing what seat width "fits" the range of sit bone measurements, and takes into account riding position (upright vs. aero). I also looked for dealers with the BG system and there is nothing close (nearest is 220 mi. away) so I'm hoping that info isn't accurate and my LBS can help me.

Grasschopper
04-19-05, 08:08 AM
On the Specialized site, they have a chart showing what seat width "fits" the range of sit bone measurements, and takes into account riding position (upright vs. aero). I also looked for dealers with the BG system and there is nothing close (nearest is 220 mi. away) so I'm hoping that info isn't accurate and my LBS can help me.

Wow you don't have a Specialized dealer within 220 mi of you? As others have suggested I would say you can replicate the test I just didn't want you or anyone else to mistakenly think the number you get when you do it is the saddle width you should get.

smoke
04-19-05, 08:12 AM
i agree with everything said about the specialized sizing, but i'll throw in my two cents for koobi. it's a tad wider than a lot of racing saddles, and it has the anatomical cutout all the way to the front of the nose. i need a wider saddle and also the cutout, and i swear by this thing. you can only buy 'em online at koobi.com, but you get a thirty day free trial, which is more than enough to decide if you like it or not. they are made for koobi by selle italia, i believe, and the build quality is as good as you would expect from a selle italia saddle. after you come up with a good width, go to their website and see if they have a saddle that fits you. if so, i recommend them highly. and no, i don't work for them, but their product sure works for me. i have another one in the mail right now; should arrive today

zanq
04-19-05, 09:39 AM
Wow you don't have a Specialized dealer within 220 mi of you? As others have suggested I would say you can replicate the test I just didn't want you or anyone else to mistakenly think the number you get when you do it is the saddle width you should get.

I had done a search for dealers with the BG system and that's what it said, but I just called my LBS and they do have it, so I'm all set. A buddy of mine said to give it a little more time, so I will in the interest of saving money but honestly I'm not hopeful. What I feel and what I've measured seem to be pointing me toward a wider saddle.