Help with roadie sizing, please?

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Joined: Sun Feb 03, 2013 05:44 am

Help with roadie sizing, please?

Postby codemavn » Mon Feb 04, 2013 13:04 pm

Hi all,

Long time lurker, first time poster.

I'll thank everyone firstly for the mountain of info I've gathered here for quite a while. I've been a long time MTBer and am moving to roadies (MTB=just not fast enough). So after a long while of saving i've stashed some cash and am looking to splurge a little. I'm from down under, which is a place known for getting proper shafted on pricing, so I'm hoping to buy online as i can get price less than half of what I'd pay here (even after shipping taxes etc). So I'm looking at frame sizing and I've gone through and measured everything up 3 or 4 times to make sure I've got the right numbers and here's what I have:

Height: 1.71m
Inseam: 833mm
Trunk: 595mm
Forearm: 345mm
Arm: 645mm
Thigh: 624mm
Lower Leg: 542mm
Sternal Notch: 1.408m

(wow, longer legs than i would've thought... given that I'm male :))

I took the numbers as suggested in the Competitive Cyclist's Fit calculator and punched the numbers in and got the following:

Seat tube range c-c 53.9 - 54.4
Seat tube range c-t 55.6 - 56.1
Top tube length 52.6 - 53.0
Stem Length 10.8 - 11.4
BB-Saddle Position 71.3 - 73.3
Saddle-Handlebar 51.5 - 52.1
Saddle Setback 6.2 - 6.6

Now, from the geometry of the bike I'm looking at:

Seat Tube (C-C) 510mm (this is "virtual" assuming a horizontal top tube due to "compact" style)
Top Tube (C-C) 530mm (again, virtual)
Top Tube (C-C) 520mm (actual)

Seat Tube (C-C) 530mm (virtual)
Top Tube (C-C) 545mm (virtual)
Top Tube (C-C) 534mm (actual)

Seat Tube (C-C) 550mm (virtual)
Top Tube (C-C) 560mm (virtual)
Top Tube (C-C) 549mm (actual)

As you can see, depending on which measurement to use I could justify any of them. Given, however, the length of the top tube being considered most important, I did a little math.

Range of top tube, plus range of stem leads to a TT/stem combination between about 63.4cm and 64.4, which would be a small frame with a 120mm stem (which seems a bit of a long stem really) or a medium with a 100/110mm stem (which seems far more reasonable). If I went the large, it would move the headset up for a higher position (and some 6mm over the recommended c-c) but would need to drop the stem to a something around 90mm.

Which I guess, brings me to the question, What do you all recommend?

Thanks in advance!

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Re: Help with roadie sizing, please?

Postby smidsy » Mon Feb 04, 2013 16:24 pm

Nothing beats going into a shop and sitting on them.

By the time you have sat on 3 or 4 different makes you will soon see that the numbers are essentially pointless.

And WTF is all this virtual stuff - get a bike that actually has real measurments (e.g 1 where the tubes are actually the size they quote) :-)

IAH teh geometry tables etc are all totally mis leading - you need to sit on a few.
Yellow is the new Black.

Posts: 2
Joined: Sun Feb 03, 2013 05:44 am

Re: Help with roadie sizing, please?

Postby codemavn » Tue Feb 05, 2013 03:39 am


I guess I'll be heading to the LBS. The only issue is I know no-one who stocks those frames here in Sydney. I guess i'll look for alternates/similar bikes and then choose a similar size based on that.


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