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Technical FAQ with Lennard Zinn: Cyclometer on ’cross bike; removing sealant from tubulars; shifting on a Roubaix

  • By Lennard Zinn
  • Published Dec. 20, 2011
  • Updated Feb. 28, 2012 at 4:47 PM EST

Reader Jeff's tool for removing sealant from cyclocross tubulars at the end of the season.

Q. Dear Lennard,

Love cyclocross and have two quick questions:

Is it cool to mount a cyclometer on your cyclocross bike, especially when racing?

Is it me or does it seem that a few ’cross pros use them, but maybe about 25 percent. Why or why not?

―Scott

A. Dear Scott,

My impression is that no pros use them, and I think it’s because they change bikes, so a computer on the bike only records the laps the bike does, not necessarily all of the ones the riders do. And of course, snapping it off in a crash or tangle with another rider’s bike is always a possibility. I personally keep a Garmin in my pocket to record everything regardless of what bike I’m on, and then I don’t worry about breaking the mount off, either.

—Lennard

Q. Dear Lennard,

I was rooting through the garage looking for something approximating the small metal tube that you used in your article on removing sealant from cross tubulars. I ended up crudely duct taping a small inflation nozzle of the type that comes with floor pumps or small compressors to the hose on my shop vac. This setup turned out to be very effective and fast.

While I didn’t measure the amount of sealant recovered, there was quite a bit in the hose of the vacuum afterward, and since the nozzle is a clear red color, I could see it being sucked out of the tire. It took only about a minute or so per tire to get most of the sealant out.

—Jeff

From the mailbag

Regarding shifting problems on a 2011 Roubaix SL3, I received a lot of mail, and following are some ideas for improving shifting on them, including some ideas that would improve shifting on any bike:

Q. Dear Lennard,

I was just browsing your posts and saw the one with the guy having trouble with his Dura-Ace derailleurs and Ultegra shifters. We see lots of this sort of thing at the bike shop where I wrench, and there are several fixes, but a couple obvious ones his shop may not realize, and we have corrected another via Specialized.

He doesn’t say what chain or generation of derailleurs he’s using, which can make a big difference. Although he’s not having issues (that he knows of), he may not realize that the new 7900 front derailleur is not compatible with anything but 7900 shifters.

Also, there seems to be a slightly noticeable difference in shifting depending on which chain is used with the new generation of Shimano parts, especially with something like a KMC versus a new Ultegra chain. Shimano really does seem to work best with the appropriate Shimano part.

The bars that are coming on many of the new Specialized bikes also have such a tight bend that the housing creates excess friction unless routed around the back of the bar, creating a wider bend.

You mentioned the hanger, so I might add that the majority of the derailleur hangers we see aren’t aligned on new Specialized frames, although this is usually not visible to the naked eye. It seems to take effect after the wheel is clamped and the hanger sits against molded carbon, which isn’t perfect.

If he’s not used to the new shift-lever feel, that will take some getting used to also. as they are not (in my opinion) anything like the older Shimano feel. These are the most frequent issues with new Shimano in the large amount of assembly and repair we do.

—Leif

Q. Dear Lennard,

I work at a very reputable bike shop that sells Specialized and I work on many of their models and significantly on the SL3 Roubaix. When one of these bikes is built up with the newest generation of Shimano Dura-Ace/Ultegra (6700 and 7800) we have noticed significant friction issues, especially between the rear derailleur and the rear shifter.

Specialized has informed (we told them) us to uncross the pre-run shift cables and replace the supplied plastic ferrules with metal ones. If that doesn’t work, they said to also replace the cables with Shimano-specific cables and housing. The use of Shimano-specific cable grease is also recommended.

It seems that the internal cables routing on from the levers to the downtube entry might be too high for the cables to run smoothly (too many harsh corners to create friction).

If this had happened to one bike, I wouldn’t have thought it a big deal but this has happened to almost every model we sell with a Shimano drivetrain in virtually every size run (I know because I have done all the work to fix this issue on customers’ bikes).

Also, when Specialized is pre-running cables on the Roubaix SL3, they are running the SIS cables on the inside of the handlebar. Since Shimano now has two positions under the bar tape (inner and outer) most companies are running on the inside. Where I work we have seen that contribute to shift cable friction and improper shifting.

—Your friendly neighborhood wrench (requesting anonymity)

Q. Dear Lennard,

I have a 2011 SL3 Roubaix with the internal cable routing. At first I thought it would be great, but it’s a real PITA, and I had rear derailleur shifting issues as well.

After many frustrating hours, I finally got some consistent shifting by using a Jagwire cable set, and keeping the routing of the rear casing as short as possible.

You absolutely don’t want to use an in-line cable adjuster with it either. Of course, it’s necessary on the front.

It may be that there is just enough flex in the downtube wall where the cable stop is to make the difference.

—Paul

Q. Dear Lennard,

In your recent column on the SL3 frame, if it is indeed a Roubaix, there is a 0.5mm spacer that needs to be installed between the derailleur and its hanger. Otherwise, try as you will, it will not shift right. It ships with the Ultegra bike and we have used it with success.

—Brad

A. Dear Brad,

I asked Nic Sims, the global marketing manager for Specialized Bicycles, about this. He told me: “There was a kit that is available from the customer service department that would rectify shifting problems with Roubaixes. The shim was a small piece that was used for SRAM only, and it pushed the derailleur over so that it would shift down into the 11 better.”

But if I understand you correctly, apparently it came with both in SRAM and Shimano bikes in some cases.

Adding space between the derailleur and the hanger increases the spring tension and essentially makes a derailleur pull harder on the cable.

― Lennard

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Lennard Zinn

Lennard Zinn

Our longtime technical writer joined VeloNews in 1987. He is also a framebuilder, a former U.S. National Team rider, and author of many bicycle books, including Zinn and the Art of Mountain Bike Maintenance and Zinn and the Art of Road Bike Maintenance, as well as Zinn and the Art of Triathlon Bikes and Zinn's Cycling Primer: Maintenance Tips and Skill Building for Cyclists. He holds a Bachelor’s degree in physics from Colorado College. Readers can send brief technical questions to Ask LZ.

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