Advice on road frame sizing, please...?

[bradh]

I was hoping that someone with more experience with skinny-tyred machines than myself might be able to help me out. I'm looking to buy a second-hand road bike, because my physio tells me I'm supposed to be riding more to aid recovery from an ankle injury, and I figured a roadie might be a bit more comfortable than my converted Giant ATX-870 commuter, which is principally set up for darting through traffic.

I'm 179cm tall, with a 78cm inseam. What size frame should I be looking for? I understand that top-tube length is probably the measurement which is of principal concern — is this correct? And, specifically, would a 57–58cm frame be too big?

Also, if it makes a difference to sizing considerations, I can't see myself heading out for 4-hour+ rides. I'm much more likely to go out for an hour or so, and push myself quite hard during that time.

Many thanks, in advance.

 

[bighitter]

you would most likely need to be on a circa 52-53cm frame (c-t)
either way a 57-58 cm frame will be way too big.

 

[jeb123]

i've got a roadie and its a large frame, i'm 190+cm tall but i have long legs commpared to most ppl, i, would go to a extra large frame size cos it would stretch me out to much, so a medium to large frame would be best

 

[bradh]

Thanks for the replies.

you would most likely need to be on a circa 52-53cm frame (c-t)
either way a 57-58 cm frame will be way too big.

52-53cm c-t sounds quite small... is there a particular formula that you use to work it out? I've googled 'road frame sizing', but have found wildly diverse information.


Also, for those who prefer imperial, 179cm = approx. 5'10" and a half.

And I know that I really need to sit on the bike(s) to check how it feels, but I'm trying to get a head start on the process.

 

[craign]

IMHO the most important thing for road frame sizing is top tube length. I'm just under 170cm and need a 53-54 cm top-tube for my build. I'm guessing from about a 55.5 to 58 cm top tube might be right but it depends on your build and flexibility. Get a good shop to help you with fit.

 

[Bodin]

I'm 185cm (6'1") and I can't remember if my frame is 57 or 58 (it's custom), but it's one of them, so if I were you, I'd be concentrating on the 55cm mark.

You may have a body shape that suits a certain geometry, though, so I wouldn't be making a purchase without test riding a few different sizes (and brands).

 

[Fatman]

Bodin speaks the truth,

I had to try quite a few 56cm roadies before one fit me, Cannondale turned out to be just right. You must get your leg over a few different models before you buy one. Any competent bike shop should be able to size you up on a new bike. I can't remember the magic formula for sizing but I know it didn't really work for me. As usual different manufacturers measure their sizes differently making it more difficult to find the right size. Make sure you do get the right size or the results can be rather painful. Good luck.

 

[bighitter]

formula for sizing is .67 x inseam = frame size c-t
.65 x inseam = frame size c-c

Ive had fittings by professionals (not lbs employees) and these formulas are very close

 

[bradh]

OK, thanks all. Sounds like doing it cheap and properly is going to be rather difficult, if not impossible. Maybe I'll get lucky, but it sounds like the particular secondhand bike I had my eye on is going to be too large.

Thanks again.

 

[Bodin]

Maybe I'll get lucky, but it sounds like the particular secondhand bike I had my eye on is going to be too large.

My first ever road bike was way too large (61cm), but I ran it with a really short stem and no seat setback and I got 2 years' comfortable use out of it. I just had to be careful not to knacker myself every time I got off the thing... For me, it was a great way to ride a full carbon frame for not much more than a thousand bucks for a couple of years.

I'm not recommending that anyone buys a frame that doesn't fit, but I will say that you can work things to your advantage when you're constricted by a budget.

 

[bradh]

My first ever road bike was way too large (61cm), but I ran it with a really short stem and no seat setback and I got 2 years' comfortable use out of it. I just had to be careful not to knacker myself every time I got off the thing... For me, it was a great way to ride a full carbon frame for not much more than a thousand bucks for a couple of years.

I'm not recommending that anyone buys a frame that doesn't fit, but I will say that you can work things to your advantage when you're constricted by a budget.

Hmmm, thanks for that. Hopefully I'll get a chance to sit on it and see how it feels.


Anyway, I could post a wanted thread, but, since I'm already typing in here does anyone have or know where I could get a cheap but decent 54-55cm (or equivalent-sized compact) frame (I have some parts) or bike?