Code Monkey

i'm considering getting a bike with a sloping top tube... the bike that it's replacing is a regular frame road bike... i was comfortable with that bike and i'm trying to get a bike that is not terribly different from that one (in terms of the position i am in when on the bike)... i test rode the sloping frame and didn't really notice the difference... i only test rode it for 20 minutes and i'm worrying if it would be a different case on a 3 hour ride... i concentrated more on looking at the effective top tube spec... the bike i'm considering is only 0.6cm shorter at the effective top tube than my previous bike... so in theory, i'm gonna be in almost the same position except more seat post is exposed... i also read Cannondales little write up against sloping top tubes ( https://www.cannondale.com/bikes/innovation/sloping.html ), but their arguement applies little to me because they emphasized more on weight rather than geometry...

any advice...?

jchet

I recently went from a 62CM Bianchi with a straight top tube to a 60 CM sloping Orbea. I have about two weeks of training on the Orbea and seemed to have adjusted. My weeks have been about 8 hour weeks with one ride at about 3 hours. Other then adjusting seat post length it seems to be OK. My stem length stayed the same but I increased my crank length. So far I like the new set up. I found at 6'2" a lot of high end frames were not available in a 62CM size. This bike seems to be awesome and I'm pleased with the design.

ImprezaDrvr

I went from a 60c Cannondale to a 60c sloping Orbea as well. While the geometry is noticeably different, the fit is fantastic. I'm using the same stem and crank length, and all's well. It handles differently, but that was expected. I think you can definately pull it off, and I was a huge skeptic before I got this bike. That said, some compact frames are more compact than others, and some offer more size options than others. I'm still not sure about the companies like Giant that offer only three or four frame sizes in a compact frame. Orbea offered as many compact sizes as regular sizes.

Code Monkey

hey ImprezaDrvr, what do you mean that it handles differently...? is it more twitchy...? that's what i noticed when test riding, especially when rocking the bike back and forth during out of the saddle climbs...

ImprezaDrvr

Not twitchy, not necessarily worse. Every company builds bikes with different geometries. A Trek rides differently than a Lemond, and they're both owned by the same folks. It's not just the compact frame that lends itself to a different feel. You can't really talk about geometry in terms of the frame style alone; it's the manufacturer.

Some of the twitch you noticed could be the stiffness of the smaller frame under you. My bike is steel, but the one it replaced was aluminum. The new bike feels like it's stiffer in the bottom bracket. There are countless variables that make this the case, but the smaller triangles in the frame figure in.

All of that out there, it is true that a compact frame is going to have to have different angles in the frame to end up with a smaller frame that still fits taller riders. Now, we're getting in over my head. I won't talk out of my ass; someone more knowledgeable about geometries needs to chime in to speak to whether or not compact bikes are inherently different than regular bikes in terms of effective geometry.