Hi Binky!
Warning: Long post ahead.
If you change from Comfort to drop handlebars, you will likely have to change your shifters as well to accommodate the difference in handlebar grip diameter, so keep that in mind.
I'm going to reach back a ways in the archives for my past posts on a related topic. I'd urge you to read these first...
https://thorncyclesforum.co.uk/index.php?topic=4939.msg28811#msg28811...and...
https://thorncyclesforum.co.uk/index.php?topic=10737.msg77527#msg77527[Some of the related links mentioned within those links no longer connect, because we changed domains since they were posted. I'm engaged in the slow and tedious process of going back through ALL the Forum posts of that era and updating them. Until I get them all updated, the old links will work if you replace...
https://thorncycles.co.uk/forums/ ...with...
https://thorncyclesforum.co.uk/ Do a copy-paste of the updated portion and you can view them easily as they're still there. Same with photo attachments that have no thumbnails. Click on them, then download to view locally on your device]
The summary version:
While a frame with a "long" top tube is not ideal if you need shorter *and* drop handlebars, you can certainly make it "better". It just depends on how much distance you need to make up. My Nomad Mk2 was definitely not recommended for use with drop handlebars, but by choosing a Medium (rather than Long top tube version) frame size, then fitting compact drop handlebars and a stem with shorter forward extension/reach, I was able to duplicate the positioning on my other bikes with "standard" length top tubes that had longer-reach stems. YMMV may vary; "how long is a piece of string?". Some measurement and careful parts selection will be required.
As the two links above indicate, the important distance for steering leverage is not handlebar placement, but the lever arm (distance) between your hand grips (whether drop or straight or comfort 'bars) and the steering axis. Get that the same or similar, and perceived steering effort will be very much the same. So long as your hands remain at a similar distance from the steering axis -- whether forward or back or widthwise -- the steering will feel similar, rather than more twitchy. Counterintuitive, but it is a matter of leverage rather than placement. This is why my 1 liter bidons placed immediately around the steering axis have no noticeable effect on steering.
The one negative difference I have felt related to stem length came from fitting very long-reach stems on frames with short top tubes. I needed to fit narrower bars to compensate and keep the same moment arm to avoid the feeling of a "tiller". Also, with more body weight forward over the front wheel, handling suffered. This doesn't seem to be the case when weight is moved more within the wheelbase of the bicycle, rearward of the front axle centerline.
As a hobbyist framebuilder, I have made a variety of stems for the folding small-wheeled bicycles I brazed-up from raw tubes. Because the main frame spar was so much lower than the handlebars, I had freedom to empirically test the effect of long, short, and negative stem reach and this is what I concluded. Allowing for a head tube declined rearward, the stem I designed and chose for my suspension design is effectively zero-extension (Photo 1 below) and I'm happy with the handling. I can and have reversed it with no ill effect on the ride. I pair it with a bullhorn pursuit handlebar (and bar-end shifters) that can be reversed along with the stem to achieve a very upright cockpit if desired.
Wrt drop handlebars, brake lever bodies (where the hands perch when riding atop the hoods) have also become much longer over time, mostly to accommodate the internal mechanisms of brifters (brake levers-shifters combined). This was copied in standalone brake levers by Tektro and other brands so cockpit sizing would be the same with, say, bar-end shifters fitted. If you commonly ride atop the brake levers with drops and have either bar-end shifters or downtube shifters fitted, a swap to smaller brake lever bodies will also effectively shorten the cockpit. 1980s vintage Dia-Compe, Shimano, and Campagnolo brake levers of that era and earlier were all much shorter reach and work fine with cantilevers or calipers but not standard v-brakes. If you must have v-brake compatibility, then fitting a leverage-altering pulley like the Travel Agent or mini-Vs can create a cable-pull match with the older, shorter levers.
Photo 2 below shows my position on my 580M Nomad Mk2 with Medium top tube. I like the overall feel very much.
The calculations for all this are pretty straightforward and "subtractive": Simply measure where your hands are now, then progressively remove the distance to match where you want your hands to sit atop drop-bars and the brake hoods.
A helpful review of *extremely* short and zero-reach stems can be found here, along with a discussion about them...
https://theradavist.com/zero-offset-and-reduced-offset-mountain-bike-stemsMore here...
https://www.bing.com/search?q=bicycle+with+reversed+stem&cvid=270a18bdb6644449a78b88aebb55939f&gs_lcrp=EgRlZGdlKgYIABBFGDkyBggAEEUYOTIGCAEQABhAMgYIAhAAGEAyBggDEAAYQDIGCAQQABhAMgYIBRAAGEAyBggGEAAYQDIGCAcQABhAMgYICBAAGEAyBggJEAAYQNIBCDY4NjBqMGo5qAIIsAIB&FORM=ANAB01&pcmpc=PCMEDGEDP&ucpdpc=UCPD&PC=UCPDDBhttps://bicycles.stackexchange.com/questions/10236/is-reversing-the-stem-pointing-it-backwards-a-safe-way-to-reduce-reach-lengthhttps://theradavist.com/raised-reversed-mountain-bike-stem-reviewDo be warned, however: If you do fit drop handlebars to a reversed stem, the arc of travel will be around the rear of the pivot point/steerer. This means (and especially so with drop handlebars that...drop), the sides of the 'bars will be below the level of the top tube and so limit the available travel 'round the arc. This should not be a problem, as most steering is done by a combination of leaning and small corrections in arc. You'd be most at risk of 'bar-tube collision during tight turns at low speed.
One last thought: If you prefer the palm-facing orientation of riding atop drop handlebars, one way to achieve that on a too-long frame is to fit bullhorn pursuit handlebars (Photo 3) reversed and flipped with your present stem. Your hands will be oriented similarly with palms facing, but much closer to you. To get a bit more aerodynamic for headwinds and such, you can always slide forward to the cross-portion of the handlebar. You'd need to replace your present brake levers with "interrupter" levers intended as supplements for cyclocross and gravel bikes, due to the difference in grip diameter between road (23.8mm) and MTB (22.2mm) 'bars. That's how I handle braking on my Folders. The interrupter levers are available in cable-pull ratios suitable for road/canti- or v-brakes. Might have to change your shifters, too.
Whew! Good luck!
Best, Dan.
