Bike Fit

[Leazerbeam]

Hello. Although this is my first post, I have been reading and learning for awhile. What a valuable source of information this forum is!

I am considering purchasing a bike that was returned by another customer at my bike shop. It's beautiful, hardly been ridden, and has good components.

I can't determine if the bike frame is too small. Bike shop said they can make it work but are not advising one way or the other. Have already lengthened stem and have an offset seat post. I need to be back further because I feel like I'm scrunched up. They have suggested a seatpost with more offset might work.

I guess my question basically is: how do you know if a frame is too small and how bad it is to extend both the seatpost and stem to inordinate lengths to make it fit?

The top tube is 1'1/2 inches shorter than my current bike which fits well and I've never had any physical problems riding this bike.

Thanks to whomever might offer advice.

[indysteel]

Based on what you've shared, I'd say the bike sounds two small. One and one half inches is a BIG difference in terms of bike fit.

Let's start with your seat post set back. Your saddle should ideally be set up so that your knee is roughly over your pedal spindle when your pedal is at three o'clock. I say roughly because some people like to be a little behind (I'm one of those) or a little forward of this position. But it's a good starting point. From there, the fitter should tinker with your saddle height and may have to fiddle with fore/aft position again before you lower body is set up correctly.

At this point, you can begin to play around with your upper body position by doing one of several things: Playing with stem length and rise, changing the spacers below or above your handlebars, adjusting the handlebars themselves. There is some limit to the changes you can make on the front end of the bike before the handling gets weird or you feel off balance. Even if you make certain changes, i.e., lengthening the stem, the bike could still feel too cramped for you.

YOU SHOULD NOT adjust your saddle in order to effectively lengthen or shorten your reach. So, when you go to the LBS to get fit on this bike again, tell them in no uncertain terms that you want your saddle adjusted with respect to your knees, not your reach. From there, play with the stem to see if a modest change helps. I'm guessing, however, that the bike is too small for you and that you're just going to feel cramped.

I have a bike that's too small for me. Notwithstanding a number of tweaks and multiple professional fittings, it's just not comfortable. I bear way too much weight in my hands and even a short ride kills me.

[Leazerbeam]

Thank you - quick question. You said that 1 1/2 " was a pretty big difference in the top tube. My current bike has a traditional straight top tube and this one has a sloped tube. Does that add to the problem?

[indysteel]

It doesn't add to the problem, so long as the measurement's you're using for the compact (sloping) frame is the "effective" top tube. Imagine a horizontal line parallel to the ground that goes from the center of the seat tube to the center of the head tube.

What two bikes are you comparing and in what sizes? Most bike manufacturers post their geometry specs, for current and past models.

[Leazerbeam]

Mine is an older Trek 5000 and this one is a Independent Frame - hence my excitement about a bargain. But I guess a bargain isn't a bargain if it doesn't feel right.
When I measure the effective slope it is 2 " shorter. Maybe I'll just keep saving for my own custom frame.

[indysteel]

You might be right.

Can you take the IF frame out for a test ride? That might tell you all that you need to know.