My standard road size is 54, Would I be able to ride a 57 ?

Short answer is yes you will be able to ride it...will it "fit" you, probably not.

I think it's usually a safe bet to go larger or smaller by about 2cm, but no more. Some peeps may disagree, but that's my feeling. Also, keep in mind that different bikes have different proportions. For instance, my bianchi is a 53, my Lemond is a 53, but the Lemond is too big because the top tube is much longer. Make sure you get more details on the size.

You really don't want to go so big that you have no standover clearance, especially if you are still sexually active.

Sure...why not.

Honestly, this is kind of an unanswerable question, as no one knows anything about how it was determined that your "standard" road size is 54cm, your cycling frame of reference/experience, what your measurements are, or how you ride. Some are of the opinion that, in general, riders often ride a frame that is actually too small for them to save marginal amounts of weight over a larger frame and compensate by having long seatposts and stems. Can you ride a 57? As the last poster said, "sure, why not?". You may not be happy with the fit, but if a 54 truly is a frame that generally fits you, and you need no accommodations to long/short torso or legs, a 57 is not likely to fit you well. Depending on where you started, a 57 could be the ideal size for you based on various philosophies about fit.

All sizing questions get flamed on this site. Don't bother asking; you will get the standard "can't size you over the internet" response. Usually by some jerk who thinks he is some cycling God..

PMS day? No helpful input from you... It's not like you can't get in the ballpark through the input of others, but it's like me throwing, "can I ride a 58.5 or a 60?" out there - you know nothing about me, have no clue about me physically or otherwise and would have nothing constructive or meaningful to say. Plenty of people post fit questions and there aren't many "flames" in this forum. There are usually a lot of helpful suggestions when there is something to go on - you want flames? Try some other sites. This is by far the most friendly, helpful and congenial site out there - especially for new cyclists. Guy didn't even mention if he was new or experienced. You wouldn't necessarily start at the same place depending on the questioner's frame of reference. If you can provide anything meaningful with the information provided, have at it - you're clearly better than I.

Yeah sorry guess I was kinda grouchy. Still you did agree that you can't fit him off that.

There is no such thing as a "standard" 54 or a "standard" 57. Your question is unanswerable without knowing the specifics as to how those two frames are measured - CTC or CTT? Compact or not? What size stem are you using now? How far behind the BB center do you sit now, would you be able to move a bit forward?

If you have the flexibility to ride with the reach of a 57, there are plenty of compact 57s that will meet your standover requirments. If your reach is just right on the 54 and you're using a 130 stem, well a 110 would bring you into spec.

Give some additional information if you want a serious answer.

depends. most of the standard formulas for bike size -- inseam x 0.65, or inseam x 0.667 -- calculate bike size measured from the centre of the bb to the centre of the top tube. this is the traditional way to measure bike size. the problem with this is:

1. not all bikes are measured c-c. treks measure from the centre of the bb to the top of the collar, meaning that a 56 cm trek is actually closer to a 54 cm in traditional sizing.

2. the most important metric of bike size is top tube length, assuming that you have enough standover height. that means that, if you have a long torso, you'd probably fit better on a size up in a trek [for example]. a 54 cm trek has a 54.6 cm tt, but you might be more comfortable on a 56 cm trek [remember, this would be a 54 cm bike measured c-c] with a 56.2 cm top tube. some manufacturers build with longer top tube, though; a m/l litespeed siena, for example [compact frame with a virtual 55 cm size] has a 56 cm top tube, and my 50 cm marinoni [measured c-c] has a 53.5 cm top tube.

3. compact frames have relatively more standover height than traditional geometry frames, so you could straddle a larger compact frame without sacking yourself if you need the extra top tube length.

my own experience is this... i have been riding my 50 cm marinoni for several years. according to the standard formula, my size would be about 51 cm. however, by trek's measuriung standard, it would be a 52.5 or 53 cm bike [measured to the top of the collar], and i am very comfortable [counter-intuitively] on my 52 cm kona cyclo-cross bike. however, i've always found the 53.5 cm top tube a bit short, even with a 11 cm stem.

this year, i got a litespeed teramo in size m, a virtual 53 cm compact frame. it fits absolutely perfectly with a 54 cm toptube and 10 cm stem. the headtube length is identical to my marinoni, but the headtube and seattube angles are slightly slacker. the fit is so much better -- even though i was always comfortable on the marinoni -- that most of my riding buddies have commented on how much better it is when they see me ride.

so the answer to your question really is "it depends." if you ride a 54 cm bike, measured c-c, with a relatively long top tube [say, 55.5 cm] and a long stem [say 12 cm] and feel comfortable, then there's no reason why you couldn't fit on a 57 cm frame [compact or measured centre-collar] with a 57.5m toptube and a 10 cm stem, assuming that you have sufficient standover.

the important thing is to compare apple-to-apples, lengths-to-lengths. take a tape measure to the bikes.

I've been riding a Trek 2100 in 54cm for the last thrirteen years. I just bought a 2004 model 2300 in 56cm. The bikes are almost identical in size. My LBS measured everything so that all the adjustments on the 2100 are duplicated on the 2300. The new bike feels a little different, but thats because the parts are shaped differently e.g. handlebars, brake hoods, saddle. After speding several hours on the web reading all the links suggested in this forum, I've come to the conclusion that if the bike feels comfortable, it fits, assuming that you can stand over the frame and that your position looks reasonable. If you are a racer looking for maximum performance, then all of the technical measurements may help, but for most of us, if it feels good it is good.

Why don't you try find the same brand at an LBS and get on it? We shouldn't betaking business away from LBS but somtimes if I am going to buy something (usually used), I check it out at the shop then I know what to buy online