Originally Posted by
Andy_K
Yes but
-All cheap bikes tend to be heavy
Nope. My used Lava Dome cost me more than my used Sirrus, but the Lava Dome weighed a ton more. This is utterly predictible - MTBs are made a lot stronger than hybrids, especially sports hybrids. The MTB has to be good to take repeated 4 foot drops, the hybrid doesn't. Strength costs weight.
, and many old MTB have easily trimmed excess weight in the wheels and handlebars. I think 25 pounds is easily in reach with the right frame (e.g. Rockhopper or Stumpjumper rather than Hardrock in the Speciailized line).
Yes, you can lighten an MTB. But why bother when a hybrid starts out perhaps 4lbs lighter for the same price used on ebay? Why pay extra money (and to lighten a hard-tail MTB by 4lbs costs a lot) and do extra work (to get 4lbs off the weight you'll have to change the cranks and forks and maybe the BB) when sports hybrids that can take 32mm tyres like the Sirrus are easy to find?
-26 inch wheels accelerate better, which is obviously good for CX
I have a physics degree: don't provoke me into doing the maths! Trust me when I say that you're wrong. (The reduction in rotational energy is trivial as a part of total kinetic energy requirements - which mostly consist of rider KE - and the work that has to be done against rolling resistance during acceleration is increased - this matters enormously on rough ground.) Really, if you were right then pro racers would race crossers with narrow 26er wheels.
, and wide tires where allowed (i.e. almost all amatuer races) aren't such a bad thing and on many courses are a distinct advantage.
This may be true. But it hardly helps if the young lady wants to learn to how to handle a cross bike with a view to racing at a higher level as an adult, which she probably does. She should be learning the feel of handling a crosser, not an MTB.
No, I thought about suggesting that the OP look for a Kona Explosif frame myself, but for this use it would be wrong. His idea is the best one.