's Forum Archives - General

Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )

An Efficient Fitting(3 posts)

An Efficient Fittingwerdna
Jan 23, 2002 12:09 PM
Yesterday I raised my seatpost and I pushed my seat back a little on the post. I had the seat all the way to the front because when I got my road bike I was unused to the stretch of road biking. (I started out mountain biking. I also thought that the top tube was too long.) The top tube may still be too long. My fore-arms are relatively short - I have a 43.5 (9 and a half) size shoe. Before raising the seat height I though my leg was too bent when I was on the downstroke, so I raised it some. So anyway, after changing the setup I realized it was uncomfortable. I slid forward the seat but I kept the same seat height. It feels different. My leg is less bent on the downstroke now. Anyways, here is my question: How can you find the most efficient fit? It seems that there are multiple ways to achieve KOPS (sliding seat forward/back, raising seat) so I am unsure about what to do.

Thank you,
re: An Efficient FittingRayBan
Jan 23, 2002 1:01 PM
Hi Andrew,
a very tried and true method of establishing your seat height/position is
multiply your inseam measurement(in centimeters) x .883 and set the low point of the saddle measured from the center of the bottom bracket to this. When on the bike drop a plumb line from the bony bump underneath the soft space below the knee cap and the string should intersect the pedal spindle with the bike level and the cranks in the 3-9 oclock position. This is a nuetral starting position. And seat height will vary within 1 cm of that. Setting the seat back is popular for gear mashers and its set forward for spinners.
The neutral position is a great place to start.
Agree that finding neutral position and then experimenting (inbill
Jan 23, 2002 2:22 PM
SMALL increments) with different positions is the way to go. I have a thing about the ".883" method, though.
The measurement of your inseam is a flawed exercise. You have different length legs, for starters, and I defy anyone to measure within a cm or .5 cm tops. If the maximum accuracy is +/- .5 cm, then you're talking about getting to the closest cm, really (or the closest two cm if you accept that your accuracy is no more than about a cm, which is what I think). Then you want to multiply by a three digit number. The result is a falsely precise number. Add to that the uncertainty of your shoe sole/cleat height, your precise normal toeing up or down position, and you have all sorts of ambiguity in your result.
I won't tell say you're crazy for using it. It probably gives a fair approximation (I've never tried it myself) of a starting position. I just want to emphasize that there is no magic and a good bit of devilry in the method. Don't worry too much about the number you get and certainly don't worry about why you may be uncomfortable there, if you are. You just have to experiment.
I myself just sort of eyeball my knee extension and/or raise the saddle until it feels uncomfortably high, with my hips rocking, and then back off a little. Very scientific.
I also agree with those who think that KOPS is overrated, if nothing else, for the simple reason that you move around on your saddle all the time, and the angle of your body on the bike in relationship to how your knees move as you pedal changes all the time, depending on whether you're up high, in the drops, climbing, sprinting, descending, whatever. I remember a link to a site that described in great detail how the center of gravity is really the critical dimension, which changes, and you just have to do the best you can. KOPS in that one place on your saddle just doesn't to me seem to be a very critical dimension (unlike, for example, total TT length, saddle height, or, the most stupidly critical of all, where very minute differences can feel huge, saddle pitch (you know, angle) and saddle axis (square with the bike)).