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-   -   Seat height/width question (http://www.bikeforums.net/general-cycling-discussion/87914-seat-height-width-question.html)

 chris hansen 02-12-05 05:59 PM

Seat height/width question

Hello,

I'm trying to decide if my seat is the right height. At the bottom of the stroke my knee is just a little bent but I can straighten it and lock it with very little movement, it doesn't feel like my hips are rocking. Does this sound too high? Another thing is that it feels like my legs are rubbing against the side of the seat but I'm trying to decide if the seat is high and I'm reaching or if the saddle is too wide. The bike I'm riding is an old Gary Fisher mountain bike with the handlebars about an inch lower than the seat. I got the seat from my old bike which had the handlebars about an inch higher than the seat. The seat is also an inch or two wider than the one on my road bike so I suspect it's a little wide.

Another thing I'm wondering is a seat height calculation I saw. It said to take your inseam (about 35) and multiply it by .885 which gave me a recommended seat height of about 31 inches. When I measured my current seat height it was around 37 inches already and I was going to raise it more because it felt too low! I had my wife watch me pedal and she said my feet are about parallel to the ground. Am I just doing something wrong? I measured my inseam by pulling a book up to my crotch and making a mark on the wall, then measured it with a tape measure. I tried it several times and always came close to the same number.

Thanks.

 alanbikehouston 02-12-05 09:08 PM

If your leg length from the floor to the pubic bone is 35 inches, most formulas yield about 31 inches. That 31 inches is measured from the center of the bolt that attaches your crank arms to the bottom bracket, on up to the top surface of the saddle near the widest portion of the saddle.

The published "formulas" was designed to obtain maximum power efficiency for a young, athletic Pro rider. It is NOT designed for "Joe Average", not does it factor in "comfort" for your knees or comfort for your crotch. Pros are paid to suffer.

I also have a leg length of about 35 inches. A 31 inch setting forced me to rock a bit on the saddle, and left me with a numb crotch and sore knees. Through "trial and error", I brought my road saddles down to about 29 1/2 inches.

Eddie Borysewicz reviewed some of the original rider's data that led to the "formula". He noticed that for SOME Pro riders, lowering the saddle an inch INCREASED their efficiency. So, the "formula" does not even work for all Pro riders.

For example, Pro rider, Alexi Grewal was most effective at 93% of the height set by the formula. Eddie B. also suggests lowering the saddle a touch under the following conditions:

- cold weather, when wearing heavy clothing

- long daily distances

- sore knees when using the "formula height

So, I would suggest you set your saddle at about 30 inches, and try that for a week or two. As you experiment with different heights, try to change only about 1/4th inch at a time, and give your legs a week or two to get used to the new position.

Eventually, you are likely to find a setting somewhere between 29 1/2 inches and 31 inches that works well for you. Then, set all of your road bikes at the same measurement, to avoid problems switching bikes.

 PWRDbyTRD 02-12-05 09:23 PM

I ride a bit lower than the way you describe your ride. I am about to lower it a bit more since I start bouncing @ high cadences. As far as your seat rubbing, is it a wide saddle? maybe you're riding too far back on the saddle...I was riding too far forward on mine and had a sore region for a good while. might wanna go to the LBS and get fitted.

 phantomcow2 02-12-05 09:42 PM

Well i dont know if this is incorrect or anything but i sit on my seat, extend a leg almost so its straight and my heel is on the bottom of the pedal. I like this, its a comfortable position i feel like i can generate a lot of power.

 operator 02-12-05 10:57 PM

Quote:
 Originally Posted by PWRDbyTRD I ride a bit lower than the way you describe your ride. I am about to lower it a bit more since I start bouncing @ high cadences. As far as your seat rubbing, is it a wide saddle? maybe you're riding too far back on the saddle...I was riding too far forward on mine and had a sore region for a good while. might wanna go to the LBS and get fitted.
Bouncing is not related to your seat height.

 chris hansen 02-12-05 11:44 PM

Quote:
 Originally Posted by alanbikehouston Eventually, you are likely to find a setting somewhere between 29 1/2 inches and 31 inches that works well for you. Then, set all of your road bikes at the same measurement, to avoid problems switching bikes.
The interesting thing is that 31 inches would be way too low. I had mine set at 37 inches and raised it up even higher because it felt low. No matter how I measure and re-measure my inseam always looks about 35 inches. It doesn't make sense.

 chris hansen 02-12-05 11:47 PM

Quote:
 Originally Posted by PWRDbyTRD As far as your seat rubbing, is it a wide saddle? maybe you're riding too far back on the saddle...
It's actually the widest saddle I own. If I look, I can see a butt print and it looks like I sit a little towards the front.

I'm going to switch saddles with another bike tomorrow and see if it makes a difference.

 alanbikehouston 02-13-05 12:03 AM

Quote:
 Originally Posted by chris hansen The interesting thing is that 31 inches would be way too low. I had mine set at 37 inches and raised it up even higher because it felt low. No matter how I measure and re-measure my inseam always looks about 35 inches. It doesn't make sense.
Measure your leg from the floor to the pubic bone. Your "seat height" is measured from the center of the bolt that attaches the crank to the bottom bracket up to the top of the saddle. (Not the middle of the saddle..."top" is the "seam" between the side panel of the saddle and the top panel of the saddle).

For a leg length of 35 inches, the "seat height" is about 30 inches. Also, when the crank exactly "in line" with the seat tube, the distance from the top of the pedal bolt (from where it meets th the crank) to the top of the saddle will be about 36 inches (depending on the length of the crank).

 chris hansen 02-13-05 01:55 PM

Quote:
I measured my inseam by pulling a book up to my crotch and making a mark on the wall and then measuring the distance from the floor to the mark. It's always about 35 inches.

Quote:
 Measure the distance from the center of the bolt on the bottom bracket (where the crank arm is bolted into the bottom bracket) to the top of the saddle. (Not the middle of the top of the saddle...to the "seam" between the side panel of the saddle and the top panel of the saddle).
With the pedals in the bottom position, inline with the seat tube, I measured from the top of the pedal to the top of the seat. Maybe I'll go measure from the bottom bracket to the seat and see what it looks like.

 chris hansen 02-14-05 06:00 AM

I measured from the bottom bracket to the seat and it was about 31 inches. I guess it helps to know where to take the measurements from. Actually it was about 31.5 inches so I lowered it 1/4 inch and that seems like the right height.

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