burnthesheep

Different drop bars have different reach distances for the hoods mounting point also. Sometimes some millimeters hidden there.

I run what I think I remember is a 75mm on my cyclocross bike. Bike is a hair large for me, but I'm really used to it now and don't notice. Then again, with 180 slow speed turns maybe the shorter stem in a cross race works out fine.

Wider drop bars also steer "slower". So I have the wide cross/gravel style bars on that cross bike with a 75mm stem. So kind of balances out. Lots of mountain bike stems are really short, their steering input being slower due to the wide bars.

genejockey 

I'm 5' 11 1/2", with a 34.5" inseam. Mostly I ride 58cm frames, but I have a 59cm and one 61 cm. They have 58.5 cm TTs, and I use a 110mm on one and a 120mm on the other. My saddle is fairly far forward, though, because I have shortish thighs for my leg length. Bar drop on my bikes runs from 8-10.8cm. I do not get upper back pain. When I've been stretched out too far, I got LOWER back pain. I also prefer 44cm bars, because even 42s feel constricting. Are you sure it's not the 38cm bar that's causing your upper back pain?

dabac

I’ve got reduced range of motion in my lower back. On a supposedly correctly sized frame I’ve used a 40 mm stem.
IMO, horrible things related to handling entirely failed to occur. NBD

seedsbelize 

60mm

canklecat

I'm 5'11", 33" inseam, arms a bit longish out of proportion to the rest of me. Usually I'm most comfortable on 56-58cm frames.

On the road bikes with 56-58cm frames, the shortest stem I've used was 80mm or 90mm. It was comfortable while I was recovering from neck and back injuries. But a bit twitchy on fast curves with rippled pavement at around 20-30 mph. At slower speeds, and most pavement, no big deal. After the neck and back issues improved I switched my road bikes back to stems of around 110-120mm. But I also switched to compact drops with slightly shorter reach across the tops/hoods for comfort.

My largest bike is around 60cm, a bit too big for me. I switched it to Nitto albatross swept bars, so now it's comfortable with a 120mm road bike stem. The original stem was a 120mm dirt drop type stem, one of those slightly upward-angled stems, but it felt a bit too high with the swept bars. The bike fit is okay, even if the frame is a bit large for me. But I wouldn't try it with drop bars. I'd need a shorter stem, which would make the handling twitchy.

Chandne

Yeah, steering will often feel a bit "looser" or twitchier as you shorten the stem. Since I am used to short stems and slack headtube angles on mountain bikes, it does not bother me. Some may find it wierd since it will quicken up the steering. I put a bit more weight on the front a bit more on sharp/fast turns if I feel I have too much rearward bias. On really steep climbs, I do the same thing but it is all second nature now. You have to make sure the front does not get too light in certain scenarios. I'd guess that will start to happen at 90mm or under, especially if the stem has more rise than the normal 6 degrees. Ocne you make a change, it really takes 4-5 rides to get used to it. If all you have is flat land, it matters much less.

Kapusta

As someone who needs a generally high stack/short reach bike, the best results I get is to go with the frame with the reach I want (the smaller size) and use spacers and/or riser stem to get the bars where I want them.

Iride01 

I got my 70mm stem the other day and replaced my 100 mm stem. Same angle on the stem so no other differences other than I did move a 5 mm spacer from top to bottom to move my bars up.

I can't say that I noticed any difference. Certainly not like the difference I noted when going from 42cm wide bars to 38cm bars a few months prior. That really messed up my handling of the bike to keep my line on twisty downhills and surprisingly gusty conditions where it seemed like I had to use more than normal effort to control my wheel when coming into open areas where the wind changed or when next to the reservoir. But I got use to it and if I hadn't had the other, I'd be none the wiser.

Maybe if I hadn't changed the bar width earlier, then I might have felt something. Or perhaps the shorter stem and narrower bars together are a better combo together. I did feel that I had more control on those twisty downhills and in road hazard avoidance too. On a part of my ride with mottled shade and bright sun on the road, I didn't see a hog snake until I was about to run over it. But I was able to snap the bike over just enough to avoid it. And that sort of snappy steering I've been missing out on since I quit riding my Raleigh.

Laifer69

Ave Maldea in Cainta does steel custom frames at very good prices. I had one made many years ago with Deda Zero Uno tubing and the workmanship was flawless.

Maybe that’s something you can consider if you really need a custom frame?