Between sizes?!
 

I've been riding size small bikes forever, and they're okay, if a bit cramped; I always assumed that was normal. I test rode this 48cm Kona Dew Plus and it fit like it was custom made for me; I didn't want to take it back to the shop! Unfortunately, the top tube hits bone. I also rode a women's Specialized Sirrus in medium, and ran into the same issue. What do I do with this knowledge? The only thing I can think of is to put on smaller wheels, but that would lower the bottom bracket, never a good idea. Stick with the smaller size and do what I can to make it fit? ...?

Any advice would be greatly appreciated.TIA.

Look up the geo chart of that 48cm Kona. Take note of the stack, reach, and standover.

Hunt around online for a flatbar with similar stack and reach, but a lower standover.

You actually don't need standover height. You need to be able to reach the ground with one toe, and that's it. However if you don't have that, it's a problem.

The usual thing for a too-short reach is a longer stem. How does your current bike feel cramped?

How about the Kona Coco, size=Med? It's of similar frame material, components spec, and the geometry is pretty close to the Kona Dew 48cm bike.

But the Coco has a step-through frame design. And the minor differences in reach/stack should easily be dealt with via simple changes in stem/bar/saddle.


Dew v Coco:

TT: 556mm / 550mm
ST: 480mm / 470mm
HT: 140mm / 130mm
stack: 573mm / 566mm
reach: 392mm / 388mm
standover: 745mm / 547mm
frame: 6061 butted aluminum
fork: Kona Project II aluminum
brakes: disc
derailleurs: Altus & Acera / Alivio & Acera
MSRP: $700 / $750

It feels like the top tube is too short; I can't stretch my back out quite as much as I'd like. Also, when I stand, I'm right up against the stem. My stem is stock; the specs just say 'Giant Sport' with no indication of the length, but it's pretty long. I thought standover was about emergency stops? A top tube touching bone could do considerable damage.

While that Coco is a rather cool-looking bike, I have an unreasonable dislike of step-through frames. Maybe I'll look at it some more. Thanks for doing the research!

I'm saying, "try a much longer stem." The stem on the bike to which you link looks short to me. I'm a roadie though and don't know what's normal for MTB bikes. On a road bike, 120mm would not be excessive. It's a cheap thing to try anyway.

I've never made an emergency stop which required me to put both feet on the ground. I for sure don't have the reflexes to unclip both feet while bringing the rear wheel off the ground with the front brake. In that case one would drop the butt off the back of the saddle anyway. The one thing you couldn't do would be to drag both feet on the ground in event of a complete brake failure.

Have you tried the 46 cm frame size? It has smaller wheels, and lower bottom bracket, and therefore lower top tube and lower standover height. With the lower BB it may also have shorter crank arms (which is a good thing, in my opinion). If the shorter reach makes it feels cramped, you can always use a longer stem.

Another vote here for trying a longer stem :)

IMO, going with compact geometry is also on the right track. I'm no geometry expert, but I wonder if there might be similar bikes with an even more dramatic slope in the top tube (*not* a step through).

I'm quite a bit bigger than the OP, but personally, I've had good luck going with larger sizes and compact geometry; with a horizontal top tube, I usually have to size way down and then put on some kind of crazy long stem to be comfortable. My significant other's 56cm vintage Centurion is delightful once I'm on it- but there is no way to get a foot on the ground without injury.

Looking at the geometry here, there's no sizes listed for the crank arms, so they're all likely 170. Bottom bracket height is the same for all sizes, and the wheels are listed as 650 x 47. Looks like the difference is in the head tube and seat tube lengths. The top tube is quite a bit shorter, which is one of the big issues for me. A longer stem can only do so much.