[Closed] Help with road bike sizes

I'd say 54cm sounds right.

I'm 5'11 and ride a 56, although could prob get away with a 54.

If the 54 ends up feeling a bit long, can always swap the stem for a shorter one.

I’m 5’9’ and have always ridden a 54” - however, that translates to a medium in some makes and a small in others 😩

This is one of the annoying thing about road sizing.
A 54 sounds right, but large doesn't, my mate is 6"1' and rides a large.
That's no help to you, sorry.

I’m 5’9 and ride a 54cm Cannondale Caad 12. Prior to that I had a 53cm Bordman Team carbon and I think a 54cm Caad 9.

Weird that Norco call the 54cm a large, as it really isn’t in other makes.

Cheers for all that.
The 54cm Norco would be a better choice (disc brakes and generally better bike).
The 51cm Carerra does look too small also.

Ignore the sizes, find a geo chart. Road bikes can use the number to reflect top tube, seat tube, an 'effective' length on a compact frame, or totally made up number to confuse you.

At 5'9" with 30" inside leg standard road bike position would be a reach of up to 380 and a stack of 560 or higher with a 100mm stem - pretty typical 54cm bike sizing. Given it's around town you might want an endurance position, especially if carrying a rucksack, so 370ish reach and 560+ stack (of course you can put in spacers if steerer is long enough and increase stack / reduce reach).

If pootling around town a ability to fit rack/paniers and mudguards is worth it especially if riding in normal clothes.

I would even say a hybrid might fit the bill better than a road bike, depends what town and how far he is riding.

I’m 5’ 9”, 30.5” inseam, I’ve always ridden 54cm road frames.
Except my current road and gravel bikes, which are both 56cm.
I went up a size because they are a little short.
I was also of the opinion that 54, in a road context is generally medium.

I'm 5'10 with long legs and a short body and normally go for a 54 or 55. It's mostly about reach not seat tube when it comes to sizing. It used to be more simplistic when seat tubes were typically the same as top tubes.

In my experience it's easier to size up a slightly smaller bike than size down. In theory I should be on a 56 but I end up with 90mm stems which I didn't like. Going for a 54 normally puts me in the 110-120mm range (depending on stack) which I find gives better handling.

Your lad definitely sounds like a medium though. It might help to find a fairly standard middle of the road bike and use it to compare geometry against. Someone mainstream like canyon/trek/specialised that will have well sussed out geometry and sizing charts. Problem with smaller manufacturers is that they sometimes just get it wrong or do something weird (On-one scandal?)

You want a 54cm effective top tube if he is of normal proportions. You can size down, but it is this measurement that matters most.

Blatant threat hijack - Seadog, I have a 54 Planet X carbon pro for sale if you want to drop me a message

5'9 and a bit, 30" inside leg and I'm a 52/medium in Spesh, Giant, Condor, Ribble, Pinnacle and Laverack.

54 always felt just a smidge too stretched, but I'm not that flexible.

Seat tube and effective top tube are probably key measurements.

I'm 5'10" with an inside leg of around 30".  I have a 54 Genesis CdA gravel bike and just had a M Genesis Zero road bike.  I've just replaced that with a 56 Specialized Tarmac, on which the reach is 10mm longer and other measurements are within 10mm of the M Zero (their geo chart recommends that I'm on a 56 too).  The 54 Specialized would've taken me too far the other way adn I'd have felt cramped (the Zero M must have been around 55).

Not too much help in your case I had the CdA as a starting point when I bought the Zero (ie I knew some approx measurements which I found comfortable) and ended up with an excel spreadsheet with the geometry of all bikes that I considered, which was a pretty good guide down to testing a bike I wanted but thought would be too big based on the chart, and it was.

Anyway, of the 2 you mention, I'd say the 54 has a better chance of fitting.

I'm 5'10" with a cycling inseam of ~32" (I buy 30" inseam trousers).

My 58cm Cube Attain GTC Disc has 388mm reach and 610mm stack (which breaks convention and includes all spacers under the 110mm stem).

I've been using it on the turbo over winter with all spacers under the stem, but I'll be moving 30mm above the stem ready for spring very soon, which increases the overall reach by 9mm and lowers the bars by 28mm according to http://yojimg.net/bike/web_tools/stem.php

Cube Attains have odd geo, you can usually go up a frame size over most brands, I did because I was worried about my lower back injury back then.

My 2009 Specialized Tricross Singlecross was a 56cm.

i'm 5' 9 with 32" inside leg. .I've had cross bikes in 54 and now a fairlight secan gravel bike in 54. Other road bikes i've had are 56

I think ideally i'm a 55

@nobodyofthegoat
Not just the attain, i have a cube peloton, and an allroad, both 56cm, when I usually ride a 54.

If had a few bikes and someone that size wanted a rider then I'd shove the 54 he's way.

Weirdo measurements only come into when you've been on a type of bike for a while.

I'm 5'8" and ride 56cm bikes with 120mm negative rise stems to counter the headtube height. Long arms you see!

Brands are inconsistent, I’ve got a cube 62cm and a cannondale 58cm which feels bigger. I’m 6’3”.

5.9 here and a medium in every road bike I've ever been on other than a canyon, which have silly sizing.

I don't think you can go on seat tube length as that only works for bikes with a horizontal tt.