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Ask Nick on carbon durability, carbon seatposts, KMC, mixed SRAM and Shimano

  • By Nick Legan
  • Published Jan. 5, 2012
Sanchez' ultralight, gold KMC X-SL chain. Photo: Zack Vestal © VeloNews (file)

Editor’s Note: VeloNews tech editor Nick Legan is a former ProTour mechanic who most recently wrenched for Team RadioShack at the 2010 Tour de France and elsewhere. His column appears here every Thursday. You can submit questions to Nick at asknick@competitorgroup.com, and be sure to check out Nick’s previous columns.

Q.Nick,
I am riding a red, white and blue Trek Postal road bike that I built some 14 years ago. The bike has spent its entire life in the hot and dry desert southwest. The bike has accumulated over 15,000 miles, has been well maintained and has never been crashed. I am concerned about the longevity of my carbon fiber frame and the glue used to construct it when used in this hot and dry environment. Have you ever experienced a carbon frame failure on an older bike?
Ken Almer

A.Ken,
Your OCLV frame should be good to go for many years to come, assuming you continue to avoid crashes. The lifetime of both the carbon materials and the glue used to construct your frame is longer than yours or mine. Carbon fiber has no perceptible fatigue life unless it is damaged.

I have had a carbon bike fail, but it was one of the earliest carbon bikes to hit the market. It had aluminum lugs and the bonding material failed. Since then carbon and the construction techniques used in bikes have come a long way.

So keep calm and carry on riding your Trek. But if you’re looking for an excuse to buy a new bike, I’m sure I can help with that. Just send another, more explicitly purposed email!

Q.Nick,
I have a question for you regarding titanium frames and carbon seatposts.
 
We all know that when mounting an aluminum seatpost into an aluminum or steel frame, a thin coat of grease should be used to prevent corrosion and fusion of the two materials.  When mounting a carbon seatpost into an aluminum or carbon frame, a thin layer of friction paste should be used prevent seatpost slippage.  Here, aluminum and carbon corroding together is not an issue.
 
What about carbon seatposts in titanium frames?  In theory, corrosion here should not be an issue, because both aluminum and titanium are non-corrosive.  Are carbon posts known to slip in titanium frames?
 
I have done a couple of short test rides since building up this bike and thus far no slippage.  I also noted that the inside of the seat tube of this new bike is rougher or more textured compared to an aluminum seat tube, perhaps from a milling process.
Sebastian Goerlich

A.Sebastian,
Personally I would add a bit of friction paste. I love the stuff, whether you use Finish Line, Tacx of someone else’s version. I apply it to virtually every carbon component. It allows me to use slightly lower torque settings without the component slipping. Overclamping carbon handlebars and seatposts is actually pretty easy to do. Why not, put a dab of friction paste inside your seat tube and keep yourself farther from potential over-tightening?

Q.Nick,
I ride Campy Record 11-speed components and simply love it, save for the fact the 11-speed chain has a short life span. This was also the case for their 10-speed chains. Back then, I always used 10-speed Dura Ace chains which lasted much longer. It is my understanding that in order to narrow the chain, Campy has opted to reduce the width of the rollers whereas Shimano has thinner side plates. I take great pains to keep my components, including the chain, in top condition. This includes at least twice weekly cleaning and oiling. I have resorted to using a heavier chain lube thinking this may add a few more miles. Unfortunately, there are really no other 11-speed options on the market except for KMC. I have never used the KMC and was wondering if you had any feedback on this. Is it worth the extra cost? Any other thoughts on this 11-speed dilemma?
— Curtis Reeves

A.Curtis,
Campy’s 11-speed groups do work exceptionally well. I have used KMC’s X11SL chain and I really like it. It’s currently on my Campy test bike. The quick link is fantastic as well. I experienced zero loss in shifting performance. It is spendy, but I think the KMC chain lasts longer than Campy’s. I have not had the chance to do a chain stretch test on the two, but anecdotally the KMC seems better.

What will be interesting is when Shimano launches its own 11-speed group. I look forward to trying the Japanese chain on my Campy-equipped bike.

Q.Nick,
both I and the other mechanic in my shop wanted to know if anyone has tried to mix road SRAM rear shifting with Shimano front shifting. We both believe that Shimano cranks and front derailleurs function so much better than SRAM and the integrated brake shift lever for Shimano seems to give us more leverage to make the big jump on a double. However we love double tap and the 1 to 1 ratio works better for both road and mountain. With the new Shimano directional chains mixing has become difficult. Besides having weird hand positions, we wanted to know if you think its possible to run Shimano crank and front derailleur/shifter with SRAM rear derailleur/shifter for either road or mountain?
— Drew

A.Drew,
I haven’t tried the setup you describe. But there’s no reason it wouldn’t work. SRAM is aware that its front shifting lags behind Shimano in some respects. That’s exactly why we’re looking forward to seeing the new Red group later this month. Both the crank and front derailleur are completely redesigned.

Shimano directional chains are a thing of beauty, but I’ve also used SRAM chains with good success on Shimano bikes. Compatibility issues are usually a bit exaggerated by manufacturers. I do feel that using a complete system from a given manufacturer is usually the best route to optimal performance. But in a pinch, options exist.

For many of us, tinkering is half the fun of cycling. So go for it and let me know your observations.

If you do go ahead with your experiment, I would recommend also matching brake calipers to the shifters. Cable pull is slightly different between SRAM and Shimano.

FILED UNDER: Ask Nick / Bikes and Tech TAGS: / / /

Nick Legan

Nick Legan

After graduating from Indiana University with honors and a degree in French and journalism, Nick Legan jumped straight into wrenching at Pro Peloton bike shop in Boulder for a few years. Then, he began a seven-year stint in the professional ranks, most recently serving for RadioShack at the Tour de France and the Amgen Tour of California. He also worked for Garmin-Slipstream, CSC, Toyota-United, Health Net and Ofoto. Legan served as the VeloNews tech editor 2010-2012 before sliding across the line into public relations.

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