Thanks again, C_D
True, none us would like the feeling of that top tube hitting our tender parts. But if he opts for a medium frame, he shouldn't have to worry about that, aight?

Once again, thank you Carbon_Dude.
It's good to hear that the -057 runs true to size. Knowing this, a trip to the LBS for a demo ride on a Scott Scale 900 (it pretty close, right?) makes much more sense now. I'm pretty sure about a medium frame for myself, as you also recommended. My father is actually also leaning towards a medium frame. Since he feels like reaching a little for the handlebar on his current 26'er, which has the same ETT-length as a medium -057 frame, a larger one doesn't make much sense to him (he says). It makes even less sense to him since it's a 29'er.

So what is it with this standover height? You say it is important - but why? Why is lowering the seat height and a shorter stem a good trade of for the large frame's standover height?

Thanks 

Thank you for your reply, Carbon_Dude
You're correct - those 88cm (34.65") for my own inseam seemed like a bit much for my total hight, so I did a remeasurment. And thank God for that. This time I measured only around 80-81 cm which seems more right for my 174 cm (5'-8.5") height.

Based on this new measurment, I guess that a medium frame (17,5") makes the most sense - right?

The tougher one is my father though, since he is 56 years old and not as flexible anymore.
Right now both him and I ride old 26"-wheel bikes with ETTs of 60cm (23.622") and a 100mm stems and he feels like reaching a little for the handlebar. A large (19") CS-057 has an ETT of 62cm (24.41") som worried that this would be to large for him.
Maybe combined with a shorter stem it would be ok?

Hey guys!

This site is just wonderfull. I've been reading ALOT about chinese carbon over at MTBR.com, but those threads tend to get really long and just not easy to manage through. A dedicated forum like this is JUST perfect! So thank you for that

Anyway, I'm building two new mountainbikes - one for me and one for my dad. We have decided to go with the popular and well-know CS-057 workhorse from Peter at XMCarbonSpeed.com. The CS-057 just feels like the safer choice. We are now trying to figure out what size we need and we have done some calculations online. But we're not sure if these calculated results apply to the chinese carbon frames, like the CS-057, too (I've read somewhere that they don't).

So what are your recommendations based on your knowledge and experience?
What frame size would you think would match each of us?

Here are our data...

Me
Height: 174 cm
Inseam: 88 cm 80cm

Daddy
Height: 179 cm
Inseam: 82 cm

Thank you very much!