Bike Fit

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.

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.

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?

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.

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.

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.

I did and felt all hunched up. That's when they started talking about more offset, longer stem etc.
BTW - I love your avatar (sp?). I rescue cats when I'm not trying to make too small bikes work.

Thanks!! That's Henry. He's 11. He has a four-month old little sister, an orange tabby named Izzy. We adopted her from our local shelter. I'm in love with both of them. I wish I could give a home to all our shelter cats. My DH wants only two, however. :(

As for the bike, I'd take a pass. Short of a few modest changes that don't otherwise make something else squirrelly, it just sounds too small. Shame on the LBS if they'd rather make a sale than put you on a bike that fits. I'm not saying that's what they're doing, but it sounds possible.

Hi again.
Went to bike shopt his afteroon and chatted. Clarified that although they didn't think the bike was a match, they could make it work. But said I had to weigh the "bargain" with the fact that it was a reach to fit. Overall I feel they were straight with me. Didn't buy the bike, but will continue to save until I can order my own. Only $2500 to go.......

Quote:

---

Originally Posted by Muirenn

The thing about the offset seatpost is bothering me. My understanding is (correct me if I'm wrong someone) that an offset seatpost is designed to be used in bikes set-up for time-trials. So to use one sounds like they are forcing a fit because the bike is the wrong size. And they know it!

Maybe that is a red-flag and you shouldn't get it. They want to sell because it was returned. Not because it's the right one for you.

I wonder why it was really returned?

---

I don't know about their use with TT bikes, but off set seat posts are common enough on most road bikes. In fact, they're more the rule than the exception. They can be helpful in dealing with the steeper seatpost angles that are coomon to smaller frames. I have a lot of setback on the seatpost that cam standard with my Bianchi.

The red flag for me--if I understood the original post--is that the LBs had suggested using a setback post to give her more room in the cockpit. That's not a good use of setback. Setback should be used to get the knee in its proper position over the pedal. Once that position is achieved, the rest of the elements of fit follow from there.

Leazerbeam, I'm glad they were straight with you about the bike. Too bad it won't work out. Getting an IF frame for a bargain would be sweet.

It's good that they were upfront about it. That means they care more about your healthy and well-being then the sale, which is great.

It will not be the last or only bike, I promise!

I waited a week to buy my commuter after I got on it and said, "I'l think about it."

I figured by the time I got there again it would be gone, but it wasn't. It was 1/3 of the price and had 50 miles on it lol.

Keep looking, it will come :)