Road/Race Bike Frame Size help needed PLEASE (50cm Womens)

jjbb

Hi, sorry to post this question but I have looked through what seems like a million website and shop websites with sizing charts and am still stuck.

I have bought my girlfriend a second hand race bike and think I've got the wrong size :-( It'll be her first bike so wanted something cheap to see how much use it would get before getting the perfect bike.

She is 5ft5 and I've bought her a 50cm COMPACT frame Giant racebike!
I believe a compact 50cm frame works out at circa 54cm normal! Do you think this will be alright for a first bike or have I got it way wrong and it shold be 50cm normally, not in a compact version???

(thanks in advance for any help) :-)

galaxyboy

Not sure why 50cm = 54cm but she's about the same size as me and i just got a 49cm compact ribble sportive and it's a good fit.

I'm sure if you search through Giant's web site there will be dimensions on there somewhere to help you.

keef66

Much depends on what the 50cm refers to. Top tube, virtual top tube, BB to top of seat tube? Different manufacturers use different measurements to size their frames.

If it's any help, I'm a bloke but have longer legs / shorter torso so my bike fit tends more towards womens geometry.. I'm 5'6" and ride a 51cm Kinesis racelight Tk which is compact geometry, so if Giant and Kinesis use the same sizing rules, I suspect you do have more or less the right size.

Unless your gf has arms like an orang-utan, in which case you might need an unusually long stem. And a hook to hang the bananas.

Monty Dog

The Giant you bought is probably too big - the 50cm compact / 54cm equivalent would be more suited to somebody 3 or 4 inches taller - the main probelm witll be the reach - for someone of that stature, you need something with a virtual toptube dimension of about 51-52cm whereas the 54cm Giant will be something like 56cm which would be uncomfortable and the weight distribution would compromise handling. This is not helped by the fact that proportionally woman have longer legs and therefore need shorter reach in comparison to a men's fit - in Giant sizing the 50cm is a medium, whereas you probably need a small or even extra-small.

keef66

I tried the 54 Racelight Tk and it was too much of a reach for me. Trying out various bikes I generally find I need a 50 / 51or small.

amaferanga

I'm 5'9" and I ride a medium (50cm) Giant. I think the top tube is about 55cm so unless your girlfriend has exceptionally long arms for her height then I suspect it'll be a bit on the big side. My girlfriend is about 5'5" as well and her bike has a 52.5cm top tube, but even then she needs a 60mm stem.

flybike

Pretty sure it's going to be too big. I am 5ft 7 with long arms and find my 54cm Felt Z90 with a 80mm stem to be perfect but I had to fit compact ladies bars for my small hands and that brings my reach in even further.
Looking at the Giant geometry chart the 54cm Felt and 50cm Giant frame are almost exactly the same size and geometry and I think I am at my upper limit bike frame size wise.
I am guessing ladies compact bars and a 60mm stem will make it fit, but better to have the frame the right size in the first place.
Can you swop it for the 46.5 frame size? (womens version has top tube of 52.5) should suit her much better.
Here is the link for Giant geometery (assuming I have the right model!):
http://www.giant-bicycles.com/en-ca/bik ... 553/32729/

keef66

amaferanga

Are you sure she needs a 60cm stem?? We're out of orang-utan territory and into giant squid here! Can you carry krill on a bike?

amaferanga

Dunno what you're talking about

keef66

It's not nearly so funny now you've edited it!

jjbb

Hi, thanks for all the replies. I got the below answer which seemed quite geeky on another forum, but based on your comments here, it looks like I've messed up. Thanks again

"A 50cm Giant should be OK.

Giant's dimensions are 50cm BB centre to top of seat tube.

Standover height is a tad under 31" ( the only dim specified in inches?? ).

5'5" height with a 52.5% SHR ( Sitting height ratio, norm lady ) = 31".

She won't notice 1 cm.

Reach on the Ladies frame is 5mm shorter, so take 10mm off the stem and your laughing."

amaferanga

That's some bad advice there, unless you were specifically asking about standover height. Its not the stand-over height that matters (as you obviously know) - its the top tube. There's no way someone who's 5'5" would fit a 50cm Giant with a 9cm stem.

There are a few 44cm OCR frames on ebay atthe moment if you can be bothered to swap the components over....