SCR2 - frame sizing reassurance please

[beanzontoast]

I'm 5'8 and have just tried a Giant SCR2 'Large'. I know some compact frames are intended to give a more upright position. I expected it to be too big, but it felt ok, my leg extension felt fine and when I asked the LBS guy, who I've bought from before, he confirmed my position on the drops looked right.

Am I better going by feel than size?

 

[coldash]

This a Giant SCR sizing guide

5’2” - 5’4” = XS
5’4” - 5’7” =S
5’7” - 5’10”=M
5’10” - 6’0”=M/L
6’0” - 6’3”=L
6’3” - 6’6”=XL

http://cyclestore.co.uk/productDetails.asp?productID=12117&categoryID=49

but on Giant SCRs that I've tried, I've always felt better one size up from that suggested by the table.

The most recent bike that I bought was also one size up, so maybe it's just me. I've got a long back for my height and feel too cramped on the smaller frames.

 

[beanzontoast]

This a Giant SCR sizing guide

5’2” - 5’4” = XS
5’4” - 5’7” =S
5’7” - 5’10”=M
5’10” - 6’0”=M/L
6’0” - 6’3”=L
6’3” - 6’6”=XL

http://cyclestore.co.uk/productDetails.asp?productID=12117&categoryID=49

but on Giant SCRs that I've tried, I've always felt better one size up from that suggested by the table.

The most recent bike that I bought was also one size up, so maybe it's just me. I've got a long back for my height and feel too cramped on the smaller frames.

Yes - that was the table I was expecting to go by.

This is really interesting. Your body shape sounds like mine. The guy in the bike shop said he always looks at body shape when sizing people up for bikes. Maybe he was taking this into account?

 

[RedBike]

The SCR has a short top tube and high handlebars. - I sold mine because I hated the upright riding position.

I would just look for a bike with a longer top tube. Without seeing you on the bike it's hard to tell; but I find it hard to belive that a bike thats designed for someone thats at least 4" taller is a good fit.

 

[beanzontoast]

RedBike - I was surprised, but not having experienced a compact frame before, I was expecting to feel more 'forced' into the upright position. Instead, it felt very much like when I'm on the drops of my Galaxy.

 

[RedBike]

Just because it's a compact frame doesn't mean it will have an upright riding position. If you were to try say Giants TCR (still a compact) you'd find it a completely different fit.
I believe the SCR should have a relatively upright riding position though. I think Giant call this something daft like all day positioning.



The M/L SCR is the equivalent of a 58cm traditional bike!
You need to look at where the saddle would be if it wasn't a compact frame. Imagine the bike had a level cross bar. How far above this imaginary cross bar is the saddle? Compact frames should have loads of seatpost showing.

 

[beanzontoast]

I see what you're saying Red. I'd quite like to get to the bottom of this. Take a look here -

http://www.cyclestore.co.uk/contentPages.asp?pageID=61

Following their guide for SCR-specific sizing in the table down the page, with my bare-feet inside leg to floor measurement of 32" (minus 1", minus 10" as they suggest), I come out at 53.3cm. On the table they give, M is for those with a 50cm result, L for those with 55.5cm. So on that basis, I'm closer to the L than the M.

The top tube length between the M and the L is 55cm and 57.5cm respectively - that's 25mm or about an inch different.

I have 2 Galaxies, acquired second-hand (one 1970's, one 1990's). Both have top tube lengths of 57.5cm. I acquired the first having test-ridden it and bought the second a few years later based on my experience with the first. The older bike has a much more upright riding position, due to the bar styling and stem length (smaller bars were common in those days) - otherwise, the frames are very similar. I don't ride with much seatpost showing on either.

So, based on all this, maybe it's my body shape, maybe (based on more accurate calculation) I'm actually nearer a L in the SCR, or maybe I'm used to a certain riding position. Or perhaps it's a combination of the three?

 

[RedBike]

Following their guide for SCR-specific sizing in the table down the page, with my bare-feet inside leg to floor measurement of 32" (minus 1", minus 10" as they suggest), I come out at 53.3cm.

54cm sounds spot on for a traditional flat top tubed bike.
I'm 5-10" and normally ride a 55cm frame.

On the table they give, M is for those with a 50cm result,

I don't think it does.
The size you've just calculated is for a conventional horizontal top tubed bike. The sizes listed in that tables are the sizes of compact frames, which are normally 4/5cm smaller. (54cm -4cm = the 50cm model, medium!) Which agrees with their recommendation of 5-6 to 5-11

As a very rough (and rather inaccurate) guide you can assume that the length of the top tube on a compact frame is roughtly what the seat-tube would be if the bike had a traditional horizontal top tube.

If you're looking at compact frames then i would forget all about the confussing seat tube measurements and try and find one with a 55cm top tube. (At 5-8 you'd normally want a 54cmTT, so 55cm with a long stem should be spot on).

btw, I think they're also the wrong sizes for the SCR listed in that table. There isn't even a mention of the medium large.

 

[RedBike]

I've just noticed that you're in Derby.

I would have a trip out to Brian Rourkes at Hanley. (phone up first and see if Brian is in). He has all the equipment, jigs (and years of experiance) to sort you out the right sized bike.

btw, if you're feeling flush his frames are excellent, if a little expensive.
His sites down at the minute (not the best anyway).
http://www.brianrourke.co.uk/

 

[coldash]

beanzontoast I've dug out my Giant catalogue from last year and here is some more Medium versus Large data for you to ponder

Size M = 50.0, L = 55.5
Top Tube Length M = 54.9, L = 57.5
Wheel Base M = 99.1, L = 101.7
Standover Height M = 77.7, L = 80.7
Head Tube Length M = 16.5, L = 19.0

I've had a proper bike fitting done (not for a Giant) and to the surprise of the shop, but not me, it recommended one size larger than my height suggested. Anyway, the only way to be sure is to try them out because all of these tables and sizing systems are only guidelines.

 

[beanzontoast]

Thanks for all this help, guys. Much appreciated.