MTB or Road Components?
 

This is my first build and first CX bike. I'm wondering which components are better to use, MTB or Road? I guess I'm really just talking about the derailers. I'm going to be using it primary around town and on dirt roads with a few trails here and there. I don't intend to compete with it, at least not yet.

I have can get a good deal ($330) on some used Dura Ace stuff:

- Dura Ace 9 speed shifters, flight deck ready.
- Dura Ace 9 speed rear derailleur (RD 7700), short cage.
- Dura Ace 9 speed braze-on front derailleur (FD 7700), double.
- Dura Ace 9 speed crank set, 53-39, 175 mm crank arms.
- Dura Ace Octalink bottom bracket (BB-7700). English, 109.5 spindle.
- Ultegra 9 speed cassette: 12-25.
- New 9 speed SRAM PC 971 chain.

What do you guys think?

$330.00 on a clean Dura Ace group is a good price. It's a shame to burn it up on a cross bike. If it were me, I would build up a nice road bike with it. Your really going to trash your components in all that mud and dirt. It doesn't make sense to use expensive parts IMO. Good luck

Tim

CX bikes, in all reality, are more a derivative of raod bikes instead of MTBs, even though MTB technology in the past ten years has revolutionized cycling technology in general.

With a CX bike, the gearing not very different from that of a road bike. The gearing will be a bit lower, but the range of gears will be the same, if not, less than that of a road bike. With that in mind, short cage derailleurs and derailleurs for double cranks (or used as "chain guides" on single cranks) are the norm.

Dura-Ace will work just fine, especially the used setup you've described below. Just remember, as has been mentioned already, that components on a CX tend to take more of a beating than on the road. Otherwise, $330 bucks for everything you listed? Hell, go for it and have fun.

Your list of components sounds like the stuff I took off the used Surly Crosscheck I acquired last week. Dura Ace doubles aren't really well suited to cross bike frames, (at least the Surly) and here's why.

With a 109.5 bottom bracket, my cranks were dangerously close to my very wide chainstays. With the 118.5 bottom bracket, my chainrings were so far out that using anything but the smalles cogs gave me some really wierd chainlines. And with the 53/39 setup, I needed the big cogs.

I could have gone to a triple, but that would have meant new derraileurs and a lot more money.

I ended up getting a square taper bottom bracket and taking the old Suntour cranks off my fixed gear and using them with the Surly. They were 110 bcd, so I had some options as far as chainring sizes. I went with a 48/36 setup. This gives me more use of the smaller cogs.

And the Dura Ace cranks are much more at home now on my fixie.

BTW, I put on new Dura Ace bar end shifters. They are AWESOME!

My experience with a D/A crank is very different, but so's my frame. I'm running an old Conquest and the Dura Ace fits and runs perfectly. The chainline is fine. The one thing that needs changed in the OP's component group, I'd pull that 53t ring and replace it with a 46 or 48, depending on how fast you ride on the road. Otherwise all that should work very nicely. As others have said, maybe too nice to beat up off road, but for the money that's not a bad deal. You wouldn't pay much less for new Mirage.

Ron

DA derailleurs will work just fine on your bike. I've been racing with the same short-cage DA rear derailleur for the past three seasons. It's never given me any problems regardless of the course conditions. I am, however, running a single 38t ring up front, instead of a double. I'm also using a DA bar end shifter, which is superbly reliable. My bike originally came with 105's, which crapped out completely after one season.

clean used DA derailleurs go for less than XTR on ebay and personally I'll never buy used MTB components (again). DA is tough stuff, crank issues are going to be specific to the frame you have. I run a single ring front and DA bar-end/rear Derailleur and its the most reliable solidly shifting set-up I've had on any bike.

I'm running pretty much full XTR 'just cause.' Road stuff works but doesn't seem to have quite the sealing that mtn parts do. If you ride in the dry, it isn't as big a deal.

Either way, maintain your stuff and you'll be OK.

HTH,

M