sizing mystery
 

I am riding a 54 cm aluminum trek that I purchased 3 years ago for my 16th birthday. I am still riding it but I have gotten some comments that its small for me since I have grown.
this sucks.
I am 5'10" with 32" inseam.
is a 54 cm too small? I am using a 100 mm stem and I feel like my brain has just gotten used to the fit.
Thanks

dokterd1... i'm sort like you and i left 54 when i was like 14 y/o... well the difference we have is that im talking about a 54x54 cms steel frame, versus the trek that who know how is doing to consider the frame sizing.

Eventually and probably people will tell you differently because everybody has different opinions, but as a top size you should be in a 56 right now. Now i have to translate this into modern frames ok? Now a days the measurements are so wacky that u have to buy a frame looking at the length of the bike, doesnt matter if the brand calls the bike medium, small or whatever size, always look at the VIRTUAL Length or effective length of the frame (if it is a compact or sloping geometry) with regular geometries u have to do the same, forget the seat tube size and go for the length of the frame. Frames nowadays tend to have short seat tubes and long top tubes on in other words modern bikes are longer.

Regarding stem probably the 10 cms one is too small, 11 cms might fit fine but who knows, I would start with an 11cms anyways.

Another advice, if you are looking for a new frame and u like one with sloping geometry, as i said before look for the effective length of the bike but if there is nothing in 56 for example go for the closest in the lower tear like for example 55 or 55.5. If you go over like 56.6 or 57 the frames tend to be too long in my opinion. If you are expecting to grow a few more cms i would bet to the next size if i was you. Lucky me and lucky my dad Ii stopped growing at 16 y/o.

By "effective length," ultraman is referring to the effective top-tube length, e.g. the center-to-center distance between the head tube and the seat tube measured level with the ground from the headtube. You probably want that measure to be around 52-54cm. As frame size increases, the two "fixed" measures that increase are 1) the headtube length, and 2) the effective top tube length. The other dimensions can be adjusted away using different length stems, seaposts, crankarms, etc.

Lots of folks out there who are 5'10" riding 54 cm (c-c) bikes and getting along just fine. If you are happy with the fit, why change? If you need to adjust the fit, you can get longer crank arms and a higher angled (or less down angled) stem. Or, you can get yourself a nice steel bike 55-56cm and enjoy true bliss.

Thanks for all the input,
currently the Trek im riding does not have any sloping geometry.
Ive also had some problems with the stem gashing my knee while climbing but I have a theory it only happens when I get sloppy from being tired.
The knee problems are just another factor in my sizing questions

do a search - proper frame size is not just related to height. Take the bike to a knowledgeable bike shop (where you bought it, perhaps?) and get re-fit. Maybe you just need an adjustment and stem change. 54 is a reasonable starting point for the average 5'10" person.

dmp if you pay the guy doing the sizing he will figure it out even how to fit u in a 5y y/o trike and that doesnt mean that you are in the right sizing... i have notice tall guys riding small bikes and small guys riding big frames, the curious thing is that they say they feel ok :) Other factor are styles and the MODE? Back in the day because lemond said that as back the saddle the better and still a lot of old freds are riding with that style only just because that worked for lemond. A few years ago came the mode of using super small frames and long ars seatposts. Other guys use the stand over height that really didnt work before and does not work today as a rule for right frame sizing, but some guys are still using it and still cant figure it out that different bikes have diferent BB heights and TT heights so the rule of thumb of using stand over gets out of any question right away.

Even CC sizing web program u end up with sizes a little bit off for some reason.

Sadly frame sizing is so subjective that is really hard to know or tell you that you are wrong or right w/o seeing you.

Whats the model of the bike and do you have a picture of yourself riding it?

Stem length and angle can be changed to move the bars further from the saddle and higher, if needed. A 100mm stem is on the short side.

Cycling inseam is quite different than pant inseam and some people fail to post a properly measured cycling inseam (floor to saddle-like crotch contact in bare feet). What moe important is saddle height (center of BB to top of saddle, along the seat tube centerline). If you've raised your saddle over the years, it increases the saddle to bar drop. Saddle to bar drop can vary a lot. Some people think that 5cm is normal, but even as a small rider, I use 9-11cm and the pros often use a lot more.