I've always struggled to get a long enough cockpit. My legs are short and my torso long. Normally I have the bare minimum of top tube to crotch clearance (on traditional roadbikes with horizontal top tubes) and have to push my saddle all the way backwards, to get not quite enough distance from saddle to bars.

So today I installed a longer stem on one bike. It had a 120 mm quill stem, now it has a 140 mm quill stem. Bike is 58.5 cm (CTC) seat tube, with deep drop bars. My 32" inseam can just barely straddle the top tube, in bike shoes.

Gosh - this new stem looks weirdly long. I have it slammed as low as it will go, which makes it look even more disproportionately long.

No real riding impressions yet. I rode about 10 lazy miles, with unwrapped bars, just trying to get everything adjusted right. I do like finally having lots of room to stretch out.

Has anyone used a really long stem? 140 mm or even longer? Any comments or surprises?

You might want to try a frame with a numerically smaller seat tube angle or a seatpost with a larger setback. Both of these increase the effective top tube, if you measure it from a reference point on the saddle to the 'bars or head tube.

It would also probably get your center of gravity closer to being centered over the BB axis.

Got it. Here is a picture of the bike w/ the 140 mm stem. I'm a bit limited by my desire to stay "period correct" on this particular bike. Campagnolo Record seatposts from the 1970s only had so much setback. I think (but should measure it) that the seat tube is 75 degrees.

When I Had a chance to Build my own frame I chose a longer top tube and so a shorter stem ..

(& gained : no Toe clip Overlap with Mudguards )