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Old 03-29-08, 05:45 PM   #1
Paco97
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Tailbone or Sitbone

Am I correct to assume the tailbone is different than the sitbones? The reason is that I ride a 2006 Giant Cypress with a Specialized Avatar Saddle. I realized today while riding that the part of my butt that is sore is the tailbone, when I repositioned myself to my sitbones, it felt more comfortable because they were not as sore.

Can anyone tell me what's going on here? Am I sitting wrong on the saddle? I don't think that I'm sitting to far upright, but is it normal to sit on your tailbone while riding? Sorry if this is a dumb question.
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Old 03-29-08, 06:41 PM   #2
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Your coccyx isn't meant to carry weight, so you must be doing something wrong. Can you describe your position on the bike etc? Perhaps you're not far enough back on the saddle?
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Old 03-29-08, 07:00 PM   #3
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Yes, your tailbone is definitely different from your sitbones.

Your tailbone is your coccyx. Your sitbones are your ischial tuberosities.
http://www.nervemed.com/Piriformis/PyrAnatA108.jpg

You should be sitting on your ischial tuberosities. If you are not, try sucking in your abs and curling your pelvis under a little bit when you ride. Otherwise, perhaps you need a slightly wider saddle.
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Old 03-29-08, 07:37 PM   #4
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Its kinda hard to describe my position. THe Giant Cypress is a Sport Comfort bike so I'm in a different position than a road bike, but not completely sitting straight up either. I feel like I'm leaning forward slightly to reach the handlebars.

When I got fitted for the saddle the salesmen said that I was on the borderline of sizes. I measured exactly 143mm and he said this was borderline for the 143 or the 153mm saddle, but he recommended to go with a smaller size. Makes me wonder if my saddle is too small.
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Old 03-29-08, 07:48 PM   #5
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You say you repositioned to sit on the sit bones... how did you do this? Also, in this position do you somehow fel awkward?

If you can get to where you are supported on your sit bones and it feels good, then I wouldn't jump to the conclusion that the saddle is too narrow, there may be another fit or position issue.
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Old 03-29-08, 07:50 PM   #6
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Have you just started riding it? Maybe you just need time to adjust to the novel strains and tensions riding is putting on your tailbone. Perhaps you're not actually sitting on the tailbone.

What about saddle position? Is it fairly level fore to aft? Are you sitting most of the way back on it?
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Old 03-29-08, 09:26 PM   #7
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The distance between your ischial tuberosities is very small. So I highly doubt your saddle is too narrow. I would think it is more likely that your saddle is too soft, and thus your ischial tuberosities are sinking in and pressure is being put on you coccyx.

All that being said, the Giant Cypress is a comfort hybrid bike with a very relaxed and up right seating position. I assume by the fact that you just got a new bike and that you just signed up for this forum that you have not been on a bike in awhile. The fact that your ass is not used to riding could be to blame.
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Old 03-29-08, 09:33 PM   #8
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The distance between your ischial tuberosities is very small. So I highly doubt your saddle is too narrow.
Define "very small". The distance between people's ischial tuberosities varies ... some can ride narrow saddles, others need wider saddles.
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Old 03-29-08, 09:49 PM   #9
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I'm having a hard time imaging the coccyx being in significant contact with the seat when riding just about any upright bike.
On the other hand, virtually all of my "seat" ( the body part) is in contact with the RANS Comfy Chair.


But, that's off on a tangent to the discussion.
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Old 03-30-08, 12:39 AM   #10
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It's a process of elimination. Try the wider saddle on a test ride. The shop should accommodate you on that score.

But I suspect you have other issues with tilt and position of the saddle rails on the seat post mount. The clue for me is that you say when you reposition on the saddle to sit on your sit bones, you feel more comfortable. It sounds to me that you are pedalling too far forward, with your tailbone on the nose of the saddle.And if your saddle nose points downward, you are more inclined to be riding in that position.

Does your saddle tilt downward? Do you feel inordinate pressure on your hands as you ride? If so, the saddle should be put into a level position. I always advise people that they should be able to sit upright on the saddle while pedalling with next to no pressure on the handlebars (or ride hands free) and not feel that they are sliding forwards on the saddle.

Also, does your bike feel too long for you so that you feel that you have to sit forward on the saddle to reach the handlebars? If so, that's a more fundamental problem of bike size.
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Old 03-30-08, 05:36 AM   #11
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Quote:
Originally Posted by Machka View Post
Define "very small". The distance between people's ischial tuberosities varies ... some can ride narrow saddles, others need wider saddles.
The distance between peoples ischial tuberosities does differ, but like I said that difference is very small. Less then 2cm. This is usually found in women having the larger distance. The set up of the bicycle it self and the height of the saddle in comparison to the handle bar, as well as the firmness of the saddle have a much bigger role to play in comfort.
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Old 03-30-08, 06:05 AM   #12
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I'm having a hard time imaging the coccyx being in significant contact with the seat when riding just about any upright bike...
Me too.

I would have to scootch forward on the seat and lean way back on my Townie, my most upright bike and with the widest, softest seat, for my tailbone to contact the seat.

Come to think of it I don't even have this problem on my wife's bike, and the top tube of that bike is too short for me.

Try scooting back on the seat or scoot the seat back on the bike.

At any rate, something is wrong. You should absolutely not be sitting on your tailbone. It's just not designed to carry the weight.
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Old 03-30-08, 10:25 AM   #13
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Pictures of the seat on the bike?
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Old 03-30-08, 11:45 AM   #14
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I'm having a hard time imaging the coccyx being in significant contact with the seat when riding just about any upright bike.
I'm not saying the OP is doing this, but there are some riders who sort of plop themselves down in the saddle, and slouch, as though they were sitting in their office chair or easy chair or something. You've got to think of sitting on the saddle as "perching" on the saddle (on your sitbones) ... and in order to do that, you've got to have a saddle that is wide enough, as well as some abdominal and back strength to hold the body in position. This may seem uncomfortable and awkward at first, but in the long run, it's a lot more comfortable.

And I've ridden saddles that were too narrow ... very, very painful.
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Old 03-30-08, 12:15 PM   #15
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Yes, my hands do feel a good bit of pressure while riding. Actually, I've had problems with my hands going numb. I've started to wear gloves and that helps most of the time with the numbness.

When I got the Avatar a few weeks ago, I did install it myself and tried my best to make sure it was level. I'll recheck for level.


Quote:
Originally Posted by Rowan View Post
It's a process of elimination. Try the wider saddle on a test ride. The shop should accommodate you on that score.

But I suspect you have other issues with tilt and position of the saddle rails on the seat post mount. The clue for me is that you say when you reposition on the saddle to sit on your sit bones, you feel more comfortable. It sounds to me that you are pedalling too far forward, with your tailbone on the nose of the saddle.And if your saddle nose points downward, you are more inclined to be riding in that position.

Does your saddle tilt downward? Do you feel inordinate pressure on your hands as you ride? If so, the saddle should be put into a level position. I always advise people that they should be able to sit upright on the saddle while pedalling with next to no pressure on the handlebars (or ride hands free) and not feel that they are sliding forwards on the saddle.

Also, does your bike feel too long for you so that you feel that you have to sit forward on the saddle to reach the handlebars? If so, that's a more fundamental problem of bike size.
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Old 04-01-08, 12:53 AM   #16
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Sometimes after you've made an adjustment on a saddle, it can slip. It depends on the mount and on how tight you do up the bolt(s). On my own MTB at the weekend, I had the single bolt on the seatpost mount work loose several times, and I can speak to personal experience on how a subtle change in seat level can upset the comfort levels!
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Old 04-01-08, 08:47 AM   #17
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Fit is always a matter of adjustment and compromise. If there is too much weight on your hands, you can move the seat back a bit, so more of your torso weight is centred above your feet instead of in front of them, but that can lead to you feeling too stretched. Or you can raise your handlebars a bit if you have the option, depending on how your stem is set up. As you get fitter and pedal more steadily, that also takes weight off your hands because the pedal downstroke pushes your body up...in fact during a sprint, pro riders actually have to pull on the handlebars, to keep their head down, rather than lean on them.
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Old 04-01-08, 09:12 PM   #18
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If your hands go numb, you're probably putting too much weight on them. I bet your elbows are locked when you ride, and maybe your shoulders are scrunched up. Strengthening your core will help alot with perching properly as Machka described. I've also seen saddles with V-shaped wedges cut out of the back of the saddle. Looks like that might work to relieve pressure on the tail bone for someone who might have a longer tailbone or someone whose position puts actual pressure on the tailbone.
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Old 04-02-08, 11:27 PM   #19
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Your hands shouldn't go numb on an upright comfort-type bike because most of your weight should be on your seat (as opposed to racing bikes, where your arms carry more weight). I suspect that your handlebars are too low (try raising them an inch) or your seat is tilted slightly downwards. It should be dead level; even a barely perceptible slant can have a large effect on comfort.
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Old 04-02-08, 11:59 PM   #20
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Your hands shouldn't go numb on an upright comfort-type bike because most of your weight should be on your seat (as opposed to racing bikes, where your arms carry more weight).
This is not correct. Good fit does not mean more weight on the hands on racing-style bikes.
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Old 04-03-08, 06:07 AM   #21
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This is not correct. Good fit does not mean more weight on the hands on racing-style bikes.
Very true. That's why we would do well to improve their core strength so that we can support our weight properly and reduce any leaning on the bike.
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Old 04-03-08, 01:32 PM   #22
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[QUOTE=Machka;6428219]Yes, your tailbone is definitely different from your sitbones.

Your tailbone is your coccyx. Your sitbones are your ischial tuberosities.
http://www.nervemed.com/Piriformis/PyrAnatA108.jpg

that hurts, just looking at the diagram
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Old 04-03-08, 04:28 PM   #23
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If a saddle has no cutout or depression in the coccyx area, it's very possible for someone to sit on the coccyx. And it's very painful. Ask me how I know.
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Old 04-05-08, 03:19 AM   #24
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How do you know?
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Old 04-06-08, 08:20 PM   #25
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It was a rhetorical question, Rowan!
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