I'm building up a cyclocross bike for my wife based on a Planet X Kaffenback steel frame I got off ebay. I already have 9 spd dura-ace STI shifters from another bike and I really wanted to pair these with a DA rear derailleur. The trouble is that the DA costs $115 from Performance Bike, while the 105 is only $30. I have all 105 on my Poprad and it shifts very smoothly. Is the DA really worth the extra $85??

Also - any favorite seatposts out there? Any advantage to carbon fiber?

Thanks

Rod

use ultegra, for $85 extra DA really isnt worth it, if money is an issue. ultegra imo is the best bang for buck. although theres nothing wrong with 105 either.

jeremyb

I'd stick with 105. You pretty much won't be able to tell the difference. Buy 2, and keep one for backup. I find the high end shimano deraileurs are a rip off-they shift the same as the cheaper ones, and break just as easily.

Thomson posts are nice. I have 2 and they're the best I've used. I've had them both for over a year and the seat hasn't moved on me. I'll still a little unsure about carbon posts. The term "catastrophic failure" scares me. If everything is done right they're fine, but if not the penalty can be pretty severe.

I have an Il Pompino run as an SS CX. It's pretty much the same frame as yours.

Let me know if you need any help w/ your build. I had to do some searching while trying to run cantis, finding the right seat clamp, etc.

http://www.bikeforums.net/showpost.php?p=810413&postcount=1560

I'd go for the 105 too especially if you are going to race it.

Is the DA really worth the extra $85??

Any advantage to carbon fiber?



No and No.

I'm building up a cyclocross bike for my wife based on a Planet X Kaffenback steel frame I got off ebay.

Given how heavy this frame is, you should go as cheap as possible for components. All Shimano shifts great, the only difference is weight. Its a waste of money to hang light parts on a 4.5 pound frame, and cross stuff gets broken fast anyway.

Given how heavy this frame is, you should go as cheap as possible for components. All Shimano shifts great, the only difference is weight. Its a waste of money to hang light parts on a 4.5 pound frame, and cross stuff gets broken fast anyway.

I agree. Bling out a better frame.

Honestly,
If you plan to race your bike in really nasty conditions, then you're better of with some cheaper components. DA is great but INHO it's too delicate for CX. 105 is very good choice, whereas Ultegra is great.
CX is very hard on bikes, so sooner or later your bike will get bear up no matter what.
Another option is to get some MTB components and put them on your CX bike. If you're using Shimano group, road and MTB components are often compatible. Needless to say MTB derailleurs are much togher and will take more abuse. They also work better in mud.

on a cyclo-cross bike, da is overkill. ultegra is overkill. if you go to the races, most of the guys are running 105 because it's tough and cheap. 'cross kills components, and it's easier to replace inexpensive ones. an interesting note, though... a lot of the elite and pro racers run 105 fds when they run fds at all, even if they have da. seems the 105 is way stiffer than ultegra or da, and shifts better under load.

I used 105's my first year of racing, and was disappointed by how poorly they shifted when covered with mud, ice and grit. The second year I upgraded to a DA rear derailleur with DA bar-cons. This combination has performed superbly under the worst conditions. It took a while to get accustomed to the bar-cons -- I don't shift as much during a race, but they are extremely reliable, and less susceptible to damage in a crash. I picked up the rear derailleur for $65 and the bar cons for $45 online. I think the 9-spd rear derailleurs are over a hundred bucks now, but you can still find bar cons for about $50. The DA has a much beefier return spring than the 105, which I believe is why it shifts so much better.

I luff my full Ultegra/XT setup! ^_^

Phiber -

Re: ultegra/xt...

Do "mtb" cassettes fit on 130mm spaced hubs? Are they the same spec? I want to fit an sram pg-970 9 speed on a shimano-9sp-compatible-road hub but i haven't found anything to confirm or deny this would work. I want the 11-32t gearing in the rear but I need to have road wheels.

Thanks!

Phiber -

Re: ultegra/xt...

Do "mtb" cassettes fit on 130mm spaced hubs? Are they the same spec? I want to fit an sram pg-970 9 speed on a shimano-9sp-compatible-road hub but i haven't found anything to confirm or deny this would work. I want the 11-32t gearing in the rear but I need to have road wheels.
Thanks!

Yep, it's the same. The only thing you have to watch is your rear deraileur, you may have to run a MTB or road triple.

I have SRAM PG-990 11-34 in the rear with an XT Front Deraileur and an Ultegra Rear.

Ride the best gear you can afford (don't sweat it), and replace as neccessary.

Yep, it's the same. The only thing you have to watch is your rear deraileur, you may have to run a MTB or road triple.

Thanks darkmother. I figured it was the same but I couldn't find any mm specs to make sure...

Rear derailleur is a deore xt M750 GS 9sp midcage; front derailleur will be acting as a chain watcher; the crank is a truvativ triple; the small chainring will be removed and a spot chain ring guard will be in place of the large chainring. I've been curious for a while what life would be like without front shifting while still having multiple gears. soon I'll find out.