Just wondering...

Now I know understand that bikes have a good deal of adjustments and about any bike can be adjusted to be "right" for a given person. But I have to ask if they are measured diffently by different makers.

I have been riding Cannondale road bikes for a lot of years. So when I went shopping for a hybrid, I would tell the lbs "I am very comfortable on a 56 can road bike, do you have a 24 speed hybrid that you would recommend to me that I can test ride. Frankly I started at the trek store because years ago they spend a good deal of time fitting my son to a bike. They had a couple of bikes that should be " right for me". I took each bike for about a 2 mile test ride. Both felt "loose" to me and frankly I felt cramped. Next I did about the same thing at a different store, this time trying a Giant and a Schwinn. Again they felt cramped to me. (I'm 6'1" with a 32" inseam by the way). Next I tried Specialized which had me leaning too far forward (if I'm going to have to bend over that much, why give up the ability of having 3 hand positions?)

Finally I took my old road bike in to the Cannondale dealer and explained what I wanted to test ride when I came back for my road bike. The Cannondale felt like I had lots of room and just felt "right" to me. I asked the salesperson why the difference and she said " I think measure their frames different from us..."

Is that true? Or is it that they have a problem converting "56cm" into "medium, large, Xl"???

Or is it because I have a ton of miles on Cannondale road bikes so the hybrids just feel better? My guess is that they actually measure them differently. I say that because my son's "54cm" trek was almost un-rideable for me, much more so then th 2cm difference in size should be.

Craig

All the frames are different. A frame has many measurements, and they do not have to be proportional. Usually the manufacturers' sites have a detailed geometry chart. For example, here is a link for the Quick 8 hybrid: Quick 8 Cannondale Bicycles
If you click on "view geometry," it will show all the measurements. The "size" is just one of the measurements, typically the top tube length. To make things even more complicated, the top tubes of the modern bikes are not horizontal, so the same geometry can be achieved by different brands with different seat tube sizes/head tube slopes (compensated for by the the seatpost length). A good starting point is probably the effective (horizontal) top tube length and (even better) reach. Those will be different between road and MTB. Also, head tube angles will be different.

Consult the geometry charts and test some bikes. Good luck with the new bike search!

Frame sizing and frame measuring are really two different things. Generally, a frame measurement is the distance from the center of the bottom bracket to the top of the seat tube. This used to work well when all bikes had the same shape: a standard two-triangle concept. Aluminum and carbon fiber have made various tube shapes possible so that top tubes often slope down towards the rear axle now. Imagine your Cannondale frame and just moving the back of the top tube down two inches, but lengthening it so that your "effective top tube" measurement is the same. Your 56cm frame is now a 54cm frame, even though your saddle height wouldn't change (it'd just stick out of the seat tube more) and your effective top tube wouldn't change (at least not much).

I have two Treks that I ride. One is a 1997 750 with a steel frame and a straight top tube. It does angle down SLIGHTLY, but it's more or less a straight top tube. It is classified by Trek as a 21" frame, and the center of the bottom bracket to the top of the seat tube (TUBE, not POST) measurement is exactly 21". This is often called the C-to-T measurement, or Center-to-Top measurement. My other Trek is a 2015 Verve with an aluminum frame and a sloped top tube. The whole frame has a different geometry because of the suspension fork (so the head tube is much farther from the wheel hub). It's listed as a 20" frame, and the C-to-T measurement is, indeed, exactly 20". However, it's a larger frame than my 750, despite the smaller nominal number. The effective top tube on the Verve is a little bit longer than on the 750. And if you took the Verve's top tube and imagined it to be straight back from the head tube (or nearly so), the C-to-T measurement would actually be a number of inches LONGER than what it really is.

So, although frame measuring itself often uses the C-to-T method, frame SIZING doesn't necessarily correlate with that number. That is, two 20" frames might fit you very differently, depending on various other measurements of the frame.

I get Giant's idea of just calling them "M", "L", etc, because a single number doesn't always tell you what you need to know. By the same token, though, a single letter doesn't, either.

Thus, the oft-repeated advice on this forum: folks need to actually go test-ride a bike to check fit. Because of various reasons, Cannondales and Specializeds and Giants and Treks and Raleighs all will tend to fit and feel just a little different.

As in much of life, the differences within can be as greatas those between. Bike geometries can be as great within as between manufacturers, and this is intentional and calculated to ensure your tall, skinny self, and your short, heavy neighbor will both find a bike and not haveto go to a rival across the street. These days, most huge manufacturers havevarying geometries even within categories and within specific lines. Somedifferences are quite subtle, but they are important especially to customers paying the most ridiculous prices. Yes, manufacturers A and B and i may nothave a short top tube or chain stay in a line you want, but the next time youmay have to re-examine the charts and adjust/expand your thinking.

As csport summarizes it nicely, ride the bikes and reviewand study the geometry charts to understand the (less) "loose" andthe (less) "cramped" fits. Again, as in much of life, you can also understand the compromises you'll likely have to make in arriving at what is"right for you".

Final notes: the availability and quality of geometry charts varies significantly,- again- even within manufacturers, thus limiting understanding. Good charts can now help me screen out 60-70 percent of offerings. Color helps with another 10-20.

+3.14

I was out trying a lot of bikes, and I ended up getting a Cannondale CX 4. I love it and as of today have about600 miles on it. The only major change I made was the tires as in 25c. I was still looking for a bike for my adult son. I told him I was going to get him a reasonable uned bike. He doesn't live here yet, but he will be getting out soon and will come and live with me.

So I love the 'Dale and I take it in for its first checkup, and I ask about a bike for my Son. I honestly ment like if they had a used bike. Well they gave me such a deal on the same day that a new credit card came in the mail... so I bought him a Dale Quick 4. Now I figure I told him I was going to give him a used bike, so I have been riding "his" bike a lot. In the end, I'll figure out which "used " biked is his andvwhich is mine. The best part of this is that my son is thinking I'm going to get him some used wall mart bike off Craig's list. I think he will be surprised!

Stack and reach seem to be the most important dimensions to me. I can pick a bike out without trying it if I know know those 2 numbers.