Bike Forums - Adjusting a too small frame

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- - Adjusting a too small frame (https://www.bikeforums.net/showthread.php?t=1172885)

Theoretically my Bike friday folder is Really small

but OP was talking about just an inch 52~54.. cm and assumed to be a road bike..

/...

Quote:

Originally Posted by fietsbob (Post 20935082)

Nitto S 84 Chromoly seat post has a lot of setback
https://www.benscycle.com/nitto-s84-...84_870/product
https://www.benscycle.com/Assets/pro...ge/870-164.jpg

Interesting. A steel seatpost. With plenty of setback -- 45mm. Looks to be high quality.

Quote:

Originally Posted by BobL (Post 20934596)

I'd say the tough part about answering that is how much it depends on your individual sizes; standover for your height, arm length, where you're comfortable, all that.

Having said that, I did exactly what you're talking about years ago (2003). I had been riding a Cannondale 52cm road bike and bought a 52cm Trek 5200 carbon fiber bike from eBay, not realizing the two of them measure frames differently - center to top vs center to center. The 5200 was too small. By getting a new seatpost and then shopping for a stem, I found a combination that made it a pleasure to ride. Yes, the smaller frame is more "twitchy", if you like that word. More responsive. About that time, there were interviews in the bike magazines saying that several pros liked the combination of smaller frame and longer stem for that reason.
https://cimg2.ibsrv.net/gimg/bikefor...0bf50fda82.jpg

The stem has a positive angle instead of negative (really parallel to the top tube) and was the longest one the bike shop had. The combination lifts the bars and pushes them forward. The seatpost is just a taller version. I've seen some that have a bend in the tube to push the saddle even farther back.

Back in the day, the pros tended to go to a smaller frame size because they weighed less. As you noted, frame sizes are "different" these days. I recently bought a CAAD 12 that Cannondale calls a 52. It actually measures out as a 54 which is close to perfect for me.

Do not get hung up on the alleged manufacturer stated frame size. Measure the effective top tube length, that is the frame size c/c. Most people, of fairly average proportions can accommodate a range of fit of up to plus or minus 2cm. And some people prefer a competition fit and some a French fit or something in between. At 5-10 plus and 33 inch true cycling inseam, a 56cm c/c is my size but my current favorite bicycle is a old GT that is a stated size 54cm but measure a full 55cm on the top tube and fits me like a good glove, when adjusted out for me, it gives me a good, preferred somewhat aggressive fit and does fine for even longer rides. I have a 56cm in the same bike, it feels a little big to me, not as quick, both will ride hands off under power.

Quote:

Originally Posted by Loose Chain (Post 20935777)

Exactly. Had to look twice to see if I had written this post. BTW the "something in between" is the Eddie fit.

Quote:

Originally Posted by jppe (Post 20929032)

Has anyone using a “frame too small” experienced a shimmy on fast descents? Just wondering if that could be a factor as well. Those can be frightening!

My larger frame road bike (Centurion Ironman) felt a bit twitchy on fast descents and curves when I first swapped from the original 125mm stem to a 90mm. But I got accustomed to it quickly. The overall frame geometry is more oriented toward comfort and stability in long road races or time trials, so that offset the slight twitchy feeling.

My smaller frame bike (early '90s Trek 5900) has the original long Ibis titanium stem. I suspect the bike might feel a bit twitchy with a shorter stem. It feels a bit stretched out until my back, neck and shoulders are loosened up. But it feels very stable on fast descents and curves. The LBS owner remembers those early Trek carbon fiber bikes and said they were more oriented toward long one day and multi-day stage races and time trials, and some racers found them a bit unresponsive for crits on short courses with lots of tight turns. No big deal, I'm never riding crits again at my age. Time trials, maybe.

They are good. I have one.

I usually ride 56cm bikes. I bought a used 54cm Trek 520 and converted it successfully. I added a stem riser and a long steep stem with no other changes. Very comfortable. Note that the 520 is a drop bar touring bike and I'm happy with the bars about 1-2" higher than my seat.

Remember that saddle position is set relative to your crank position. It is not used to compensate for a short top tube. You can use a longer stem and some spacers to move the handlebar up and forward but very long stems can feel awkward when steering at lower speeds.

I started out with a 19.5" (50 cm) frame on a used bike that a salesman told me was "close enough". Setback seat post maxed out of the seat tube, seat set back on the rails, stem all the way up (old style quill stem) and a couple of changes of handlebars and eventually I got it to be what seemed fairly comfortable. Then I learned more about bike fit and got some advice from someone who knew bike fitting. Turned out that I needed a 21" or 22" (54-56 cm) frame depending on geometry. New bike of the proper size, saddle mid-rail on a neutral seat post, stem actually 1 cm shorter than stock with a slight rise and the bike fits me perfectly. It is far more comfortable and handles much better. Yes proper fit does make a difference over work-arounds for a too small frame.