Three Bikes with the same frame, but different comps

I posted this elsewhere, but thought it more appropriate for here. I'm looking to pick up a new hartail, and there are three bikes with the same frame but different components. They are as follows:

Full XTR carbon crank ( Sid race) (discs): 19.1lbs @ +300$
XTR/ XT(discs)(sid race): [email protected]$
XT/LX (no discs)(sid race) 21.5lbs @-300 (-600)$




My question is this: Yeah, it would be nice to have full XTR and a carbon crank. Hell, you're riding a 19lb hardtail. However, I was originally going to get the 21lber xt xtr, because it's a step up in components from my stumpjumper. However, for 300 less I can have a 21.5 lb hardtail anyway. Sure, it's only going to be xt lx components, but it still has a sid race and is only slightly ( in my opinion) heavier than the more expensive bikes. I want to be to keep this bike for at least 5 years with potential to race it at all levels. So, my question is this, ulitmately:

Full XTR carbon crank (discs): 19.1lbs @ +300
XTR/ XT(discs): [email protected]
XT/LX (no discs) 21.5lbs @-300 (-600)

I'm a firm believer that its the rider and not the bike, to a certain extent. So, let's say my fitness level is high enough to race with guys who all have very light bikes. If I do get the xt/lx which will likely come in at over just 22lbs with pedals, will I be at a disadvantage? I could afford the full xtr bike, but I feel as if it isn't too necessary. Does XTR really offer suprior performance, or is it simply weight? Likewise, is XT that much better than lx? I'm only saying this because if I get the least expensive bike, I can also afford a 29er. On the other hand, i don't want to sacrifice performance, because I plan on racing seriously in the future. thanks for your time. i appreciate it.
Thanks!

 

I would go with the XT/XTR bike. Things like LX cassets and chains wear out really quick.

Are you sure about those weights.

My race bike is pimped to moon. Sram X0, Truvative Noirs, Avid ulimates, Stans Olympic rims, Hugi hugs, Corsa fork, Crank brothers 4ti pedals, 2.7 pound frame and it comes in at 22.

 

It would be easier to give advice if you listed the full bike spec for each of the 3 options and the overall price. e.g. what is the frameset/ wheelset? It is generally better to spend your money away from the drivetrain as that will wear and tear, and instead focus on forks, wheels etc. e.g. instead of spending an extra £300 on an xtr crank, you might be able to get a lighter wheelset which will give a better overall benefit.

Also, what rubber are you planning to use and are you a good enough rider to get the benefit of a really lightweight tyre (i.e racing on a semi-slick)? This is not meant to be patronising, I am not good enough to race on a 400g tyre as there is simply not enough grip for me and I am faster on a slightly heavier tyre that offers more grip.

Another thing is how heavy are you? Super lightweight components might not be suitable if you are not a featherweight yourself.

One last thing is have you considered a full squidger? For most courses I am quicker on my full suss than my hardtail simply because the back wheel has far superior traction.

Very finally, to the ebst of my knowledge, shimano xtr cranks are not carbon (at least not over here in the UK).