Hi – a long time ago I was all set to buy a Cotic Soda – but due to delays with the frame, and reading that due to the new EU standards the frame would be stiffer I didnt. Im only 9 stone 10, and thought that any give and spring wouldn't be worth the cash – 1 im too light, 2 the frames had to be made stiffer.

I ended up buying a Lapierre, great bike. But id still like a superlight XC machine. Could the more tech guys around here give any input on this. If I was 15 stone and buying a large frame im sure the flex would be noticeable – is it going to be the same for me????

I ride titanium (Van Nicholas Mam Tor) and am about 15 stone, no problems at all. It's not as flexible as some people suggest if it's built right, and a Soda's built right. the flexabilty comes in comparison to Aluminium which leaves you feeling battered after a long ride Titanium doesn't. It just soaks up a lot more vibration.

I wouldn't worry – the flex is only in a horizontal direction where it makes no difference to comfort (though if you interpret sideways flex as more comfortable it might be an issue).

I'd honesly buy a Soul (I owned a Soda, but now ride an IF steel deluxe) the Soul is only 1lb heavier and you'll have much more money to spend on lighter componenets.

Quality steel frames are more forgivving than Ti frames in my experience, and the Soul is a quality steel frame.

Seriously, buy a Soul.

No – I think I may have worded things wrong.

I'd like a springy, forgiving ride.

This may be possible for a 16stone guy on a large frame, but would a light guy on a small frame get the same result?????

If no, then the extra cash for ti may not be worth it….. Im constantly reading about how the Ti bikes feel the same as the steel and alu versions of various bikes in the mags

I'm not sure the difference in frame flex is at all noticeable once you've got some decent sized tyres on. I say that as bloke who switched from an ally giant to an on-one when I was about 15 stone.

My steel 456 feels more compliant than my 456Ti at normal speeds, but when tramping along its the other way around – 80kg for me.

When I was lighter, around 10st as opposed to 11.5 at the minute (bleurgh), I could feel the difference between a ti and alu frame.

I spent a fair amount of time on one of these and it was noticeable-

http://www.rideon.co.uk/shop/ViewProduct.aspx?productId=708

The stiffness to weight ratio of steel, aluminium, magnesium and titanium is much the same.

See page 5 of this:
http://reynoldstechnology.biz/assets/pdf/rtl_steel_alloys_extract.pdf
http://aluminium.matter.org.uk/content/html/eng/default.asp?catid=89&pageid=2144417038

Its CFRP (carbon fibre) that has a higher stiffness to weight ratio.