smurf hunter

I'm entertaining the idea of upgrading my Kona Dew frame with a Soma Double Cross DC. I've upgraded most everything on the Kona over tha past 5 years: wheels, handle bars, crankset, brakes, etc. and hope to re-use most everything as I am trying to watch my wallet.

I believe my Kona frame is too small. It's a 56cm with an aggressively sloped top tube. It originally fit ok when it had MTB style flat bars. Since then I've converted to On-one Midge drop bars, changed to a lower profile saddle and cranks that are 5mm longer.

Here are my current fit issues:

1) the longer cranks compressed my knees a bit too much, so I raised the saddle
2) the raised saddle pushes me further back (and looks ridiculous nearly 3 fists of post are exposed)
3) riding in the drops stretches me out and lowers my back more than even my 57cm LeMond
4) the saddle to bar drop is too aggressive for city riding - even with a steep angled up stem (that may be too long)

I've only intermediate knowledge on geometry and it's consequences, but I do know my LeMond is very comfortable (recently did some double centuries), but my Kona is painful on my knees if I mash up hills.

Here's a google spreadsheet I made comparing the geometries. Obviously it doesn't account for seat post height or stem length/angle.

Looking at all these measurements, is there any confidence that the Soma DC would fit me better? Or any simple explanation why my LeMond is a better fit?

Thanks.

illwafer

the roadies will tell you no, the tourers will tell you yes (too small).

i think you have a few issues though.
1. i think the bike is too small for your current purpose and how you ride it.
2. your crank seems to be causing you issues, and may be leading to your knee pain. if you keep the bike, get a shorter crank and lower your seat back down.

i say get a new bike.

smurf hunter

I have 2 other bikes with 175mm crank arms (which was my logic for getting the longer arms when I replaced the old crankset). The saddle heights vary on the other bikes (one's a MTB), but I can't understand the obvious knee pain from the Dew. I think I'll measure fore/aft position relative to BB and see if something obvious comes up.

DaveSSS 

Installing longer crankarms and raising the saddle makes no sense. The longer crank extends the leg further and raising the saddle extends it even more.

Duplicating a fit from one bike to another starts with the saddle. It best to use the same saddle for all bikes, otherwise you have set the fore/aft position for each one using a plumb bob off the front of the knee and the height has to be eye-balled to be close, then fine-tuned out on the road. With the same saddle, I can set the fore/aft position with a plumb bob off the tip of the saddle to the center of the BB.

As for the frame reach, the slack STA on the Lemond shortens the reach by about 10mm per degree, with the saddle in the same position, relative to the BB.

Measuring the BB drop only requires measuring the axle height and the BB height, then taking the difference.

Once you have the same saddle fore/aft position on all bikes, the reach to measure is from the saddle tip to a point on the brake/shift lever that can be identified and repeated. This take into account difference in the handlebar reach. Of course this also requires the same saddle model, unless you've set them all with the plumb bob off the knee and then checked for differences in the saddle tip setback from the BB.

dahoyle

A few questions?

First, what sizes are the other frames that "fit" you?

Second, What do you mean you raised the saddle to compensate for longer crank arms? Did your legs grow longer? You set your saddle height based on the bottom of the stroke, not the top, and the pedals are 5mm farther away than they were before, not closer. It sounds to me like the cranks are too long, if they cause problems at the TOP of the stroke.

Also, assuming that you adjusted the seat to compensate for the longer cranks, at the top of the stroke,(which makes absolutely no sense) then it would have only required an adjustment of 5mm up, which would have only set it back 2mm or so, easily adjusted by sliding the saddle forward. How did that small of an adjustment translate into something that is ridiculous, if it wasn't ridiculous before.

I see all kinds of problems, but cant point out any particulars on fixing them. Sounds to me like you are too stretched out, which is a function of seat location, top tube length, and stem length and angle.

I would have to say that if the bike fit you ok the way it was, then restore it to that configuration. There is no point in making so called improvements that make it unridable.

smurf hunter

I like the idea of standardizing my saddle across bikes.

I think a shorter stem would be helpful, as the change from flat to drop bars effectively places my hands a few cm further away.

I'll remeasure things when I get a chance - I've got some good info you people.
Thanks for the responses.

SoreFeet

3 fists of post...Too small! Unless you have really short arms and upper body its likely you have longer arms than the top tube can provide.