I would even leave out STA.

Looking at off-the-shelf or craigslist bikes, that's all you need. Seatpost height and offset, stem spacers, stem angle and handlebar specs help you get the rest of the way to fitting yourself to a bike.

I measure all of my bikes, including angles (STA and HTA), then plug the measurements into BikeCAD. Angles are easily measured to ± 0.1° with a Wixey WR300 Angle Gauge.



My 1987 Paramount as measured.



Here's the published geometry. My bike is a stock 62cm frame.



Notice the HTA is actually 73.3° instead of the 73° spec.



The STA is right on spec at 74°.

If you ride hoods majority of the time, the reach of the bar as well as the shape of the hoods have a lot impact on your riding position. There could be as much as 30mm difference depending what bar and shifters you use and how you mount the hoods. That's more than one size jump in most manufacturers' geometry sizing.

I usually just swap stem along with bars in such situations. Swapping from olde style brake levers to brifters is usually good for around a 3cm shorter stem swap.

really? you swap bar/stem among your bikes? so you have to either re-mount the shifters, re-tape and re-wrap every time or re-cable, either way, it's pretty time consuming.

Not much really. Mainly when I get a bike with bars I hate. Like my Scapin came with some godawful ergo bend bars with olde style brake levers. I wanted to put my Cinelli 66 bars on there and some Tektro RL341 brake levers, which have long slabs of hood, like brifters. So, when I did that I went from 120mm stem to 90.

I've never understood the seat tube measurement from center of BB. I measure from center of pedal spindle. Not all crank arms are equal length although, obviously, you may know if yours are.

I am pretty hypervigilant about fit but others, not so much. Two riding buddies flew into town last weekend for a charity ride. Both rented Specialized Allez bikes and each ride a carbon bike in their home town. Takeaway? They rented generically to body size...one a 56 and other a 54 and both thought their fit was better on the rented bikes than their bikes at home. Pretty comical really. Rent a bike, do a 80 mile ride and I feel better after the ride on a AL bike without a lot of fit adjustment.

I can't afford (read: unwilling at this time to pay for) a custom frame. So. i buy off the shelf starting with the usual frame size/ standover "fit".

I have had a general bike fit at the shop for 50.00 which was setting seat height and reach. I bought a stem. Months later I've fiddled with the seat enough, I'm pretty much dialed in on my dual sport.

I had a "pro" fit done on my road bike for 100.00. Measurements taken, logged, shims added, knees tracked, the whole shebang. Still had to try different stems and fiddle with the seat. I still need to go back to compact handlebars. That last one was my mistake when i bought the bike I went to a deeper drop bigger bar. Shoulda tried it first. THESE measurements are on file at the fitters.

My fat bike is technically too big as it didn't come in the correct "standover height". I set the saddle, dug through my stems, found a better one, but still not enough rise. Bought a riser bar. Pretty much dialed in now. I may need to tweak when I put clipless pedals on it.

The old rigid mtb I bought, is technically too small. Yet it didn't feel "wrong". I can't explain this. Usually I hate a too small feeling. It has a quill stem and I'm almost out of seat stem, but still safe. I raised the saddle, brought the stem up about an inch and put clipless oon it. Last night I took it for it's first serious ride. Other than too much pressure on the nethers, it was amazingly comfy. And it turned out to be a damn fast roller that I can storm a hill on.

I am in no way "limber".

To recap, I have four bikes all differing geometries. Two I fit myself, two I've had fit. One is actually on paper somewhere. I dunno.
I suppose the real litmus test is can I ride all the bikes for the same duration?

I thought it was funny that the person's hands had gloves on, like they were performing a medical procedure.

GH

Took a tape to my bikes today. BB to seat top are all exactly the same. ETT is within 3 cm of each other as is seat tube length and seat post center to grip distance. Excepting the extra reach to the hoods on the road bike.

Question: Do custom frame builders build frames down to the millimeter? Or do they have smaller increments between frame sizes than shelf mfgs?

It probably depends on the builder, but why don't you toddle over to the Framebuilder's Forum and ask there?

Hm. Having a database of those that also contained the rider's relevant measurements could be helpful for others in thinking about how to modify their bikes to fit them better (eg seat position, stem height).

April Fools! Old thread.

That's a possibility too.

So far, for me, having this information has been very valuable because it allows us to buy frames and then Rowan can build the bicycles. No test rides, etc. etc. required.



(And BTW - I linked to this thread in another thread in General yesterday ... that's why it has come up again. )