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Technical FAQ: Worlds clinchers, replacing rings, and more

Clinchers at the road worlds

Dear Lennard,
In this post about Tony Martin’s TT win on clinchers, they don’t mention if the tire setup was tubeless. If not, I would assume they would use a latex tube. Any idea which is true (or none of the above)?
— Steve

Dear Steve,
I have confirmed with Specialized that Martin was racing on latex inner tubes. The riders on the Etixx – Quick-Step team in the world championship team time trial were also all on Specialized Turbo Cotton with latex tubes.
― Lennard

SRAM/Shimano compatibility

Dear Lennard,
I have a simple question about SRAM and Shimano cassettes. Are they compatible? I have a 10-speed Shimano cassette that I would like to use with a SRAM 10-speed X0 derailleur and a SRAM 10-speed X0 twist shifter. Will this work or should I bite the bullet and buy a 10-speed SRAM cassette?
— Russ

Dear Russ,
Yes, they are compatible. That setup will work fine.
― Lennard

Replacing rings

Dear Lennard,
Will there be any problems if I replace the 50t ring with a 46t ring on a 50-34 Ultegra chainset, giving me a 46-34 setup?
— Adam

Dear Adam,
It should work OK. The shift ramps won’t be in the right places, since they’re not designed to be used together, but it will probably work fine.
― Lennard

Quick links for chains

Dear Lennard,
Your response to Glenn’s broken 11-speed chain episode suggested that the break might have occurred at the connecting pin. That has always been a concern of mine as it seems that the margin for error is pretty small. Consequently, I have always used a KMC Quick-Link for connecting my Campy Record 11-speed chains. I’ve never had a problem, and I’ve avoided having to buy the snazzy (and pricey) Campy chain tool. Granted, Glenn has 100 pounds on me and (I expect) a lot more power. What is your opinion of quick-links for 11-speed chains?
— Mark

Dear Mark,
I like them and use them personally. One time I broke a 10-speed master link on a road bike, so I know it can be done. That said, I suspect that the master link in general is at least as reliable for joining a narrow, 11-speed chain as is a connecting pin.
― Lennard

Removing sealant clogs

Dear Lennard,
A follow-up to this story: Technical FAQ: Disc brake dangers, broken chains, and more.

Regarding sealant buildup in the tubeless valve. I run sealant in regular tubes with removable cores (I have used non-removable but it’s messy and time consuming). Have you tried using an auto airline in your local petrol/gas station or garage with the valve core removed? The increased air volume may force a blockage out. I’ve used a spoke to unblock the stem with some positive effect. I’ve also found dropping the removed valve core (in open position) in boiling/very hot water and agitating the center pin with needle-nose pliers will free up the valve core of any blockage.
— Stephen

Dear Stephen,
No, I have not tried compressed air at a gas station, but I have an air compressor in my shop with which I inflate most of my tires. The tank pressure sits at 120psi, which I’m willing to bet is as high or higher than that of a gas station compressor tank. I have yet to blow a sealant clog out of its valve stem with compressed air.
― Lennard

Dear Lennard,
In your October 11 column, Jeff asked about removing dried latex sealant from valve cores. I recently learned of a product made by Effetto Mariposa called Caffélatex Remover. Works like a charm to clean clogged valve cores. A couple of drops is all it takes.
— Wayne

Rolling resistance follow-up

Dear Lennard,
Regarding your recent article about rolling resistance.

I find it VERY hard to believe that a tire rolling at 40kph can have 40 watts of rolling resistance. How are they removing wind resistance from the equation? From the spokes and general surface turbulence I mean. The spokes at the top would be going almost 80kph!

I would expect a linear relationship between rolling resistance and speed in a vacuum (how this test should be done?). If they tested a single tire at 5, 10, 15, 20 … 50kph, they may get an exponential curve, meaning it’s not all rolling resistance.
— Adam

Dear Adam,
They are not removing wind resistance from the equation. You’re right; it would have an effect.
― Lennard

Wheel sensor magnet placement

Dear Lennard,
A good tip regarding wheel balance is to place the wheel magnet for a wheel sensor where it will help with the balance. Basically, before installing the magnet, spin the wheel while the bike is on the work stand and put the magnet opposite of heavy side (on a spoke above the hub after the wheel stops spinning). Front wheels are easier to do this, because you don’t have to take the free hub into account as the wheel tries to come to a stop with the heavy side down.

Note, the balance can be further fine-tuned by moving the wheel magnet on the spoke — outward toward the rim or in toward the hub — if the sensor’s positioning allows this. After placing the magnet on the spoke, give the wheel a fast spin and check for bouncing of the bike in the stand. If the bouncing is reduced, you’re headed in the right direction with the magnet. (FYI, it’s good to give the wheel a fast spin before adding the magnet, to compare the pre-installation bounce against the post-installation bounce with the magnet.)

You can also move the magnet to the next spoke in either direction from the first location, and test these locations with a fast wheel spin to see if these spokes offer a better balance.
— Mark

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