Frankencross
 

Hi new here, this place is great, i learned a lot here. Anyways after browsing through the forum, I've seem some CX bike with MTB frame, "Frankencross," is what some called it. So i was wondering if i can build one of my own too, since i have a magnesium MTB frame that is not in used. Comments?

I'd love to do this too... I think the smaller wheels on MTB might not work as well, but I'm really curious to see if this'll work well... I've got the perfect cantidate with a great shimano exage (I think) drive train but I'm not sure if I can use it with drops and new levers... but then, what road levers would work with an older MTB 21 speed (I think :rolleyes: ) Drive train? Does anyone have experience with this?

The derailer cage needs to match the cogset\ring size, road or mtb. Speeds are in the shifter function.

If you mean to run 700 wheels, the brake caliper mounts mtb become useless. The front brake mount if you have a crown drilled (rigid) fork should be correct for mounting a road\XC caliper brake. (Mine is)
Rear brake needs the seatstay brace to be in the correct position also (mine is) though, my strut is tapped only one side lower, facing the tire, I would have to drill the brace through the side facing out and back to mount the road caliper.
Then unscrew the canti-boss anchor tubes.

Putting drops and such you'll have to be creative for levers, barcons would be cool, index shifters though?
Since mtb don't have downtube shifters, the barcons sound best to me.

Gearing...well a larger cluster =different drailer cage.
Some mtb F-derailer cages accept a few more teeth.
A triple to double switch will need the bb\axle to be swapped to run the double\chain line to the cluster centered.....I believe?

If your front was 24\34\42 you can enlarge the middle ring no problem (other than a big chain drop) as it is the sm\lrg that the cage measures.
If the derailer can take a 26\36\46 or something like that, you can start hauling @$$. also the 12-28\30\32, just pull the 12 cog off the cluster and put an 11 on for topspeed.

11 to 46 would take a real he-man to run for any time XC. I can just run 38 by 11 offroad, constant flatland it's o.k.
The reason I'm probably not going to run 700 is my 11 by 38 gearing max at 80 rpm, the speed difference between 26 and 700 was 1.1 mph. Big deal. and I lose my near indestructable 26 rims for skinnies that restrict my ability to really take advantage of offroad.

I might try keeping the 26 wheel and using a reversed mustache and road lever, barcon setup soon if i can find some nice road brake levers -more as an advanced 'flat bar\bar extension\bull. Having a smooth curved bar would give me more positions. Might need dual brake levers? The brake lever position is what I cannot decide on. V-brakes for the 26 wheel dictate the levers will be on the top\flats, not the ends.

Also, the handlebar collars for mtn brakes are not the same size as road bar collars, road bars are wider.
So there are compatibility issues for brakes in using different lever types.

It can be done..not easily..or at least not without some planning.

Well that's my musings on it, sorry its not well edited, written.

Wow! Its gonna take me a while to digest all that. And next time, do you think you could use a little more technical info? :D my brain is awash in gear ratios! I seem to remember reading that STI shifters might be compatible with some MTB drivetrains, but I can't find that info again. Has anyone done that or used those kelly barcon adapters? This is just the project I need right now!

You're kidding right? Last thing anybody needs is me attempting to 'help' them.

If you want to run 700c's on a 26" wheeled frame, its very possible. You either need Paul's Motolite (expensive) brakes or Avid Tri-aligns (rare) to do it though. If you want to use a road bar, get a road stem. Brake levers, Diacompe or someone like that makes a set of drop bar levers that are V-brake compatible if you want a little snappier feel, or they make a regular canti version as well. Make sure you get a brake lever with a return spring... cheap ones won't have it. Gearing, I would run a MTB front gearset with like a 12-25/8 rear cassette, or whatever you can find for 7spd thats close. I think it would work, and give you a decent gear ratio for CX. I've raced CX on my XC bike with a 11-34 (terrible stock cassette) and placed 19th in B's for my first race, so don't worry about gearing being too easy. Shifters, barcons are your best bet, if you can find any for 7spd.

I'm actually piecing together a similar bike for commuting/CX (shh, its supposed to be a secret) and planning on basically the same setup I just outlined. Going with the Avid Trialigns if my deal pulls through on them, but they are hard to find these days it seems.

You can use 8 speed barcons with with 7 speed clusters, no problem, you just have an extra click at one end

I can get a set of Shimano 105 Shifters really cheap right now... will these work with my 21 speed exage MTB drivetrain, and my Brakes? If not, wht would I need to do to make them compatible? It seems like the brakes should be that same... Pull lever, retract cable, brakes sqeeze wheel. I feel like I must be missing something. And thanks for all your help so far guys.