Tech & Wearables

Technical FAQ: 12-speed chain compatibility, internal cable routing, and carbon fork replacement schedule

Tips for mixing Campy and SRAM drivetrains, internal cable routing, and how frequently to replace a carbon fork.

Have a question for Lennard? Please email him at veloqna@comcast.net to be included in Technical FAQ.

Dear Lennard,
I’m about to start a bike build, perhaps my last one on a bike with rim brakes. I’m planning on using a Campagnolo Record 12-speed drivetrain along with a crank-based power meter. In your opinion, will the Quarq SRAM RED/Force Power Meter (with its AXS 35/48 chainrings) can reasonably work/shift with the 12-speed Campagnolo chain, or would I have better luck using SRAM’s 12-speed Flattop chain with the Campagnolo rear derailleur? (My guess is the former and not the latter.)
— Eric

Dear Eric,
I wouldn’t do either. The SRAM Flattop chain has larger rollers (also narrower inner width) than any other chain on the market. So, there is no way it would work with the rear derailleur and cassette. Since we were able to get a SRAM Eagle 12-speed chain to work on this bike with a Wolf Tooth AXS-Flattop-chain-compatible 1X fat/thin-tooth chainring (and an Eagle cassette), there is some reason to think that the 12-speed Campy chain might work on that AXS crank. Since the tooth valleys are meant for larger rollers, it won’t be an ideal fit, but it might be workable.
― Lennard

Regarding internal cable routing:

Dear Lennard,
The method I have found useful to fit internally routed cables on Kleins (mountain and road) is to run a length of stiff wire (I use a thin brazing rod) through the frame. It usually takes a couple of minutes of poking around and may require a slight bend in the end of the rod to get an angle so it finds the opposite brake cable opening. Once the rod is through and through, slip a piece of cable liner over the rod and pull it completely through the frame. Then with the liner in place, the brake cable can easily fit through, and the liner can be pulled out once the cable is through. I also use this method more frequently on modern frames than pulling out the Park IR1.2.
— Mike Varley, Black Mountain Cycles

Internal routing tips and tricks may all come down to patience when performing an installation—and a little savvy with a vacuum cleaner. Photo: Lennard Zinn | VeloNews.com

Dear Mike,
Thanks. Your letter reminds me that the cable housing liner is small enough to fit through those tiny holes on those Klein frames. So that’s actually a better way to use the vacuum method I described last week.

Just vacuum the string through with gravity’s assistance as I described, but don’t bother crimping it to the end of the cable (with a cable end cap with the end cut off). Instead, slide the plastic housing liner over the string (the vacuum may help getting the string through the liner as well). Slide the liner in one hole and out the other, with the string guiding it. Then slide the new cable into the liner. Once the cable is through and the incoming housing is in place as well, you can then pull the liner out and install the outgoing housing onto the other end of the cable.
― Lennard

Dear Lennard,
Reading the comments on the difficulty of threading internally routed cables which we have probably all suffered with (not aided by the fact that every frame is different!), I can’t help wondering how the bike manufacturers deal with this. Most bikes are now sold complete and assembled, unlike when I raced, so the manufacturers clearly have an effective method of dealing with this.

Any insight into this?
— Nigel

Dear Nigel,
I have seen carbon frames laid up with a plastic cable liner in place connecting the entry and exit holes for the cable. This is not possible with metal frames, since the heat of brazing or welding the housing stop that inserts into the frame would melt it.

When we used to do this kind of housing-stopping internal-cable inserts into steel frames back in the late 1980s and early 1990s, we usually silver-soldered a stainless-steel tube, end-to-end, to each of the steel ferrules that would be silver-soldered into the frame. We would then slip that entire, soldered-together assembly onto a piece of cable that we had run, by trial and error, through the frame from one of the big, angled holes we had drilled at an angle into the frame tube to the other. Then the consumer could easily slide a new cable in because it ran through the frame via that stainless-steel tube. However, cable friction was an option with that method.

Abandoning that method due to friction, in our revised version, we ran a piece of steel welding rod along the cable path, connecting the two ferrule-like housing-stop inserts while we silver-soldered them in at an angle into the frame tube. After the frame cooled, we slid the cable housing liner onto that welding rod and through the frame. Then we pulled the welding rod out and left the housing liner in place during frame painting so that the customer could easily slide their cable through the liner and hence through the frame. Once the cable and housing were in place, whoever built up the bike could pull out the liner and then install the exiting cable housing into the inserted ferrule.
― Lennard

Regarding replacing carbon forks:

Dear Lennard,
In the March 30 column, a reader mentioned a recommendation to replace carbon forks every five years. This generated a “SAY-WHAT?!” reaction and an unsuccessful search for this recommendation.

Please point me to the article or elaborate as I’m currently riding bikes from 2005 and 2013 with the original forks.
— Colan

Dear Colan,
I don’t know where Christian got that recommendation to replace a carbon fork every five years. That would be a very conservative recommendation. Because the fatigue characteristics of carbon fiber are so different from metals, I’m not sure how or why anyone would make such a blanket recommendation.

In this column from nine years ago, I address exactly that question with carbon fork makers. As you can see, none of them say anything like suggesting replacement after five years. Far from it, in fact.
― Lennard

Dear Lennard,
I note in the latest Tech Q&A a question about 1 1/8th carbon forks. Ritchey also still makes a fork in this category, the WCS Carbon 1-1/8th.

Although the rake is not what the reader is looking for, it is an alternative.
Tire clearance is 30mm depending on tire/rim combination. It’s the same fork we use on our Road Logic frameset.
— Simon Beatson, US & Asia Pacific Sales, Ritchey Design, Inc.

Dear Simon,
Thanks. The 46cm rake is indeed considerably shorter than the 50mm that Christian was seeking.

Although tire clearance for 30mm tires is advertised, in practice that may not be achievable, as the brake may be the limiting factor; often road rim brakes will not fit any taller than 28mm tires under them without dragging.
― Lennard


Lennard Zinn, our longtime technical writer, joined VeloNews in 1987. He is also a custom frame builder (www.zinncycles.com) and purveyor of non-custom huge bikes (bikeclydesdale.com), a former U.S. national team rider, co-author of The Haywire Heart,” and author of many bicycle books including Zinn and the Art of Road Bike Maintenance,”DVD, as well as Zinn and the Art of Triathlon Bikesand Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.” He holds a bachelor’s in physics from Colorado College.

Follow @lennardzinn on Twitter.