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Hey E.T.(8 posts)

Hey E.T.Spinchick
Sep 3, 2001 6:45 PM
A continuation of the previous thread: I do have a setback on the seatpost. And, I did have the seat all the way back while using the aerobars. The difference was I wasn't constantly pushing back further in the saddle. I rode again today with the aerobars and what a difference having another postition to go to makes! I don't know about the seat tube angle. I can't find my owner's manual or my old geometry textbook. No math wiz here...
OK; here's what you doET
Sep 4, 2001 1:23 AM
I need two measurements. Measure from center of BB vertically straight up to center of top tube. (This is an imaginary line, of course, which does not follow the path of any tube. Don't lean the tape onto top tube but try and make it go straight up from BB and eyeball it as best you can.) Also measure the seat tube from center of BB to center of intersection of seat tube and top tube. (Again, try not to lean tape onto tubes but keep it parallel with jutted out BB.) Preferably do these measurements a few times to be as accurate as possible. Report back with these two numbers and I can give you your seat tube angle.

If you have time and patience, also measure your top tube c-c, and also from BB to the front part of tt you already measured (i.e. center of intersection of tt and head tube). This will provide a double check.
OK; here's what you doSpinchick
Sep 4, 2001 6:08 AM
Center of BB vertically straight up to center of tt= 20 in.
Seat tube from BB to intersection: 22 in.
tt=20 1/4 in, BB to intersection of tt and ht = 24 3/4

I measured several times so hopefully it's accurate. I'm going to feel really stupid if I'm missing something totally obvious...
Tape Measure AccuracyKristin
Sep 4, 2001 6:29 AM
Spinchick, one thing you may want to do is measure your tape measure. For some bizzare reason, the one use at home (a seamstresses tape measure) was not accurate. Last month, my height was measured at the Dr's to be 5'7". I'd just finished buying a bike based on the fact that I was 5'6" tall. I went home and measured my tape measure. It's more than 2 inches off over all. Big difference.

If we can't trust measurment tools, what can we trust?
good idea...Spinchick
Sep 4, 2001 7:16 AM
I was using the same thing to measure. I'll check it out with a real measuring tape. Geez, two inches off?
so Kristin, why am I not surprised?ET
Sep 4, 2001 1:26 PM
And you expected us to fit you over the internet when even your height was way off? I wouldn't dare try again. OTOH, Spinchick seems to be much more with it. :-)
Wow...that was harsh!Kristin
Sep 4, 2001 1:48 PM
Nice to see your not bitter or anything. And besides...I never "expected" anything. I was just looking for help. There was no way for me to know that the measurments were off and I discovered it only through a coincidence. So will actually go on.
something's wrongET
Sep 4, 2001 1:21 PM
Using your 20 and 22 gives a seat tube angle of 65 degrees, which can't be. Using all the other numbers produces a more believable 72 degrees, which is still suspiciously slack for your size bike. Please re-measure the 20 and 22. As a check, please measure both of these center to center as described previously, and then also measure each center to top as well (as these numbers can also be used and will be a check on the first ones). That is, measure from center of BB vertically straight up to top of top tube (people have a tendency to underdo it by a bit; I did my first time. You have to try to get it to the very top tip of the tt cylinder. Also measure from center of BB along seat tube to where seat tube meets top of top tube (this is also further slanted away than one might first think). It would help if you had a cm tape, since that is broken into smaller segments, but if you're reasonably accurate, inches is OK.