# 54cm versus 56cm



## CarbonFrk (Jul 30, 2008)

Quick question. I recently got into this sport, and I'm currently in the market for a bike. I went to my LBS and they did a really quick fit for me on a Trek of 54cm. Now I know that there are ways to get professional fits and all, but he seemed to know what he was doing. 

This was several weeks ago, and I've been in the market for a 54cm used Trek since. I understand that different manufacturers have different fits, but I'm currently just interested in a Trek.

My quesiton is - how much of a difference will a 56cm make versus the 54cm - besides 2cm? As a amatuer in this sport, I'm wondering if there is a way to compensate the difference with the stem perhaps? Or will a 56cm just be completely uncomfortable for me? I'm a bit over 5'8" and have a 31" inseam.

Thanks!


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## Guest (Aug 15, 2008)

For the same frame going from 54 to 56 you could usually expect a taller headtube, longer top tube and of course taller seat tube. How much those things matter in a particular frame is something you would really have to find out by trying it out in both sizes with appropriate stems. There are other things that could considered such as the ease with which you could set proper seat back, larger frames are heavier and from an aesthetic point of view one might be more pleasing to the eye when set up to fit you.


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## CarbonFrk (Jul 30, 2008)

Thanks - So it looks like there are quite a few variables in this game. Looks like a trip to another LBS is in store for me to try the same model in two sizes.


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## Guest (Aug 15, 2008)

If you have the option I would try any bike you were interested in, in several sizes just to see what the differences are. You may find that neither a 54 or 56 in a certain frame (or 52 for that matter) are perfect but there may be things about the two sizes that suit you well which will help you find a different frame that suits you even better.


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## CarbonFrk (Jul 30, 2008)

Good point - I'm going to check out the same bike in a 54 and 56, along with other models. I'm hoping I fit the 56 as they seem to be a bit easier to find on the used market lately.


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## brentley (Jul 20, 2008)

Keep in mind that you are going to want to find the same model/geometry when you look for your used frame.

For example, in a 2001 5200 I was a 58, in a 2008 Madone performance (current ride) I am a 60. I might have been a 58 in the race fit. 

Just make sure you ride whatever you buy.


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## CarbonFrk (Jul 30, 2008)

Hmmm - good point. Problem is that I'm looking at the Trek 5500/5900, which of course is no longer produced. Would it be pretty safe to say I can test out a 1 series bike to check fit and it should be comparable to the 5900?

I'm also looking at older Madones - however I know the new models have different frame geometry so is there anything comparable that would be good in a test?


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## weltyed (Feb 6, 2004)

nope. 



CarbonFrk said:


> Problem is that I'm looking at the Trek 5500/5900, which of course is no longer produced. Would it be pretty safe to say I can test out a 1 series bike to check fit and it should be comparable to the 5900?


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## jsedlak (Jun 17, 2008)

Also remember you can get a bigger/smaller bike and remove/add spacers as well as flip the stem or change it all together to get different "custom" fits.


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## SkiRacer55 (Apr 29, 2005)

*Try this...*

...it's pretty interesting, because it says several important things:

- There's a range of acceptable frame sizes for a given body type and size

- There's actually 3 ranges, depending on what kind of fit you're looking for

- The frame size isn't the only measurement that matters

http://www.competitivecyclist.com/za/CCY?PAGE=FIT_CALCULATOR_INTRO

Also note, as several others have pointed out:

- Some frames are measured C-C, others C-T...so a "54" might might actually be the same size from one manufacturer to another. 

- Race frames are different than plush frames...here, I'm thinking, for example, about the difference between the Trek Pilot series and the Madone series...or the difference between Specialized Tarmac and Roubaix...or Cervelo R3 and RS.

- Once you get a frame that's within your range, you further personalize the fit with your seat height/saddle position, stem length, bar width and shape, and so forth...


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## PaulRivers (Sep 11, 2006)

While there's often 2 different sizes of bikes you can ride (56cm and 54cm, or 54cm and 52cm for example), and it's certainly true that a 54 in one frame might fit perfectly while a 56 in another frame might fit perfectly, getting a frame that's not quite your size in order to save money or because it's easier to find is...a fairly bad idea. There's only so much you can do to adjust the size. You can end up with chronic pain if you get a bike that just can't be adjusted to the right size (like my last bike).


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## dhtucker4 (Jul 7, 2004)

How tall are you? In most of the old Treks (traditional, not sloped or semi-compact), the seat tube is from the center of the bottom bracket to the top of the seat tube or the seat collar. As I remember, if you get a 54cm size - the top tube is 54 from center of the seatpost to the center of the headset or the head tube (identical). 

If you're 5'10'' or taller, you might try a 56cm size. Now, I'm 5'10" and I stepped down a size to a 54cm (I prefer a 55cm or 56cm), but I bought a longer stem and flipped it, and it's ideal. I might get a 56cm carbon frameset, because my frame is 853 steel, it weighs over 4 pounds, I want to get a carbon frame that is about 1000 grams (2.21 pounds).


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## randi_526 (Jun 12, 2008)

I'm 5'8" and have 2 bikes in different sizes. My raleigh fixed gear is a 54, and is just as comfortable as my 56 Giant road bike. Just remember that whats comfortable for one person can be a hellish ride for someone else. A friend borrowed my giant recently, and could not ride it comfortably, and he's 5"10. 

With whatever you get, be prepared to make adjustments untill it feels comfortable for YOU. When I bought my Raleigh, It was uncomfortable at first, but after some minor adjustments to the seat (and of course giving it time to break in) its great. Go for a medium paced ride, bring tools, and make adjustments along the way, and remember that any changes you make will take a little time to adjust to. I did this my 3rd day with the bike, and by mile 10, I had stopped about 4 times to play with the seat and it was comfortable.


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## PJ352 (Dec 5, 2007)

CarbonFrk said:


> I'm also looking at older Madones - however I know the new models have different frame geometry so is there anything comparable that would be good in a test?


The 5/6 series new Madones come in Pro and Performance fit. The geometry on both is the same as the older Madones, except that the Performance fits have a 3 cm longer HT. That given, you should be able to find a new Madone Pro (ideally in a 54 and 56) and once they're set up for you, know which is the better fit. Don't compromise though, because (as some posters mentioned) doing so can be a painful experience.


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## Squidward (Dec 18, 2005)

I'm almost 5' 8" and I have three road bikes. One is 51cm, one 52cm, measured center to top and both are conventional geometry steel frames. The third bike is a 53cm semi-sloping carbon bike. Since all three bikes were built by me I didn't get a chance to test ride any of them before committing to buying. Chalk it up to a learning experience. They all pretty much fit the same to me except that the carbon bike is more stretched out by about 1.5cm. I have a 90mm stem on that bike to reduce the reach from the saddle and it is flipped up to try to reduce the reach a little bit more. The 52cm bike also has a 90mm stem while the 51cm bike has a 100mm stem. The magic number for me is around 610mm from seatpost to handlebar.

My point? To me, top tube length is more important than seat tube length. The 51cm bike has a 51cm top tube, measured center-to-center. The 52cm bike is 52cm, and the 53cm is 53.5.

Also, people of the same height can ride bikes of different sizing, depending on body geometry and suppleness of the body. I guess, at 42 years old, I'm not as flexible as I used to be so I prefer a more upright riding position than I was capable of when I was half my age.

My advice to you is to try different bikes and figure out what feels good to you. Figure out what the top tube length (virtual) is and that's what you should be shooting for.

Keep in mind that there are conventional geometry, semi-sloping, sloping/compact frames out there. A 52cm conventional would fit me as would a semi-sloping with a shorter stem. A compact 52 would be too large for me as the virtual top tube would probably be around 55cm. Also, some people measure the seat tube center-to-center (c-t-c), not center-to-top (c-t-t) as is the way I've always understood as the correct way to measure a frame. The difference is about 2cm. So, that 52cm frame, measured c-t-c would be a bit too large for me.


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## CleavesF (Dec 31, 2007)

I'm 5'8" with a 30" inseam.

I have a 54cm, 18", Medium, and a 52cm

Size down bro. You will regret the 56cm.


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## idunno (Aug 7, 2008)

yep sizing down is a good way to go, making a bike bigger is a lot easier than making it smaller


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## treebound (Oct 16, 2003)

Late to the thread here but here is another thing to consider:
What accessories will you want to have on the bike?

If you go with the larger frame then your seatpost will be deeper with less extended and if you ever want to use one of those quick release racks that clamp around the seat tube you might not be able to with the larger frame because you might not have enough seat post exposed. This happened to me with one bike I used to have.

I also ran into a few issues with various seat bags not fitting well.
Just another angle to consider.


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## PJay (May 28, 2004)

*i say 54*

i am maybe 1 1/2 inches taller than you (until my muscles cramp up, then 1 inch) - with slightly shorter inseam.

i started with 54.

as you ride, i nthe first year, your body will change to where your legs can handle the reach, and your back and arms can handle the reach of a 56.

that is what ended up happening to me. when i moved to a 56, it felt funny to later get back on that 54 cuz my body had changed.

you can adjust the seat a fair amt to fine-tune. but a big deal will be the length from shoulders to handlebars - on a 56, that will be farther IN GENERAL. this is where fames will differ.

so, think of the ratio of height to length from seat to handlebars - the taller the bike, the farther away the handlebars will be. for me, with a longer torso, relative to my overall height, i prefer the 56 so the 'reach' is not too short. so, the 54 may be just right for you.

i actually lucked into a free (dumpster diving) 58 that i was able to ride OK as i spent time to clean it up in order to sell it.


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## Guest (Aug 19, 2008)

CleavesF said:


> I'm 5'8" with a 30" inseam.
> 
> I have a 54cm, 18", Medium, and a 52cm
> 
> Size down bro. You will regret the 56cm.


Yeah, but it does take allot of tweaking to get it right. It took me two seasons* to finally get my medium OCR1 dialed in right. (5' 11 1/2, 31" inseam). My position on the bike is a bit funky, but it works. 

* Partly because it wasn't till the second season that I went an got a "good" bike fit at another LBS.


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## CarbonFrk (Jul 30, 2008)

Agreed - went with the 54cm and it fits perfect. If I end up switching manufacturer, I'll go through the fitting process again.

Thanks for the feedback...


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