Technical FAQ: Aging expensive tires (and more on motors)

Lennard Zinn answers questions about aging modern tires, hidden motors, and how to custom tailor your kit.

Caring for tubulars

Dear Lennard,
In the 80s when I raced, it was fairly common knowledge that proper care of a tubular tire consisted of stretching it onto a tubular rim without glue and leaving it to age (providing it was a latex-tubed, cold-vulcanized tire). The practice supposedly toughened the tire tread, making it more resistant to punctures. At the time, I couldn’t test the practice because I couldn’t afford it! Eddy Merckx could afford to do this, and did so with good results.

Now, with the release of Specialized’s Turbo Cotton clincher tires (also cold-vulcanized, with a layer of latex rubber painted on the inside of the tire), it has occurred to me that these tires may also benefit from an aging process. If so, what would be the best way to store them? They come packaged like other folding clinchers, but I’m thinking that folded up could not be the best way to store them if one were to want to take advantage of any age-hardening process. I look forward to hearing your thoughts on this.
— Bill

From Specialized:
Our tubulars should be allowed to age for at least two months after production for the glue to bond. Ideally, the tires are not folded to not stress the bond. (That is why we don’t box them up, but deliver pure and loose with a mere hangtag on it.)

There are glued interfaces between base tape and casing and between casing and tread.

After this curing or aging period, the tire is fit for use. And we recommend it for use right away, because the compounds won’t have dried out and give their best performance. [That’s] unlike a rather old-school [approach] to age tubulars for at least a year. This advice aims at drying the tread compound. The compound hardens over time and this increases puncture protection. A dried-out tire does not collect debris as much and is a harder barrier to penetrate. There is truth to this. At the same time, anti-puncture materials got much better than they were in the heyday of [tubulars] in the 70s/80s. These fabric layers are built in under the tread and prevent most debris [from] punching through. Thus, we would never sacrifice grip and speed of the modern materials for that little extra protection a dried tire might offer.

Drying the glue does apply to the Turbo Cotton clincher. Same materials. The cotton clincher is flat though — the casing is not forced into a tubular shape and the tread is not forced to bend into the sidewall. So it can be rolled up and stored in a box no problem.

Mounting on a rim stretches and spreads the casing. It doesn’t do much for a clincher, but it helps when mounting the tubular again. Makes it easier, and easy is good when dealing with rim cement too.
— Wolf Vorm Walde, tire research and development director at Specialized

More on hidden motors in race bikes

The detector that the UCI is using is most likely a magnetometer. This would work on any frame material. It detects the magnetic field of the motor, so the motor does not have to be turned on or “hot.”

This is an easy, free app you can download on the iPhone.  I have one downloaded called “Magnitude.” There are many others.

You can use it like a metal detector, and run your phone along the bike to detect batteries or motors. Try it out, it’s pretty neat!
— James

Dear Lennard,
I’m not sure if you’ve seen this clip of Ryder Hesjedal, but it pretty convincingly looks like he was using a motor. It looks a lot like what happens in motorcycle racing when you crash and the throttle sticks wide open. I’ve certainly never seen a bicycle do this.

— Rob

Dear Rob,
Yes, I’ve seen that and had a similar impression. Interesting though that the following reader saw it completely differently. Just goes to show that we can’t necessarily believe what we see.
― Lennard

Dear Lennard,
Regarding your recent article about motorized cheating. You mention Ryder Hesjedal’s bike and that the cranks kept spinning when he crashed. This is incorrect. When his bike hit the ground, the wheel kept spinning but the cranks stayed stationary. Just an FYI.
— John

Dear Lennard,
“It sure seems like all of that mechanism inside the seattube would offer some resistance…”

It is likely they run a sprag clutch, which grabs when the shaft is rotated one way but freewheels the other. A bit like a freehub but
without the (noisy) ratchets and pawls. Sprag clutches are often found in starter motors on (real) motorbikes.

Here’s an explanatory diagram someone has been kind enough to put up.
— Stan

Dear Stan,
Thanks for that. Having used classic-technique roller skis a lot, I’m familiar with the concept and that they can run smoothly with minimal backlash.

However, there is resistance of the teeth in the spiral bevel gear, which would still be engaged. I would be surprised if a rider in this day and age who thinks they have to have ceramic bearings in their bottom bracket might also consider the resistance of the sprag clutch (that would disengage the armature) and the spiral bevel gear arrangement of this motor system as an acceptable amount of drag when the motor is turned off.

I’m convinced that nobody is sensitive enough to actually feel the difference between a good steel-bearing bottom bracket and a ceramic-bearing one while pedaling down the road. But if someone actually can, then their resistance alarms would be blaring with this system.
― Lennard

Dear Lennard,
It seems like the easy part is purchasing the equipment. I found hundreds of links to purchase the motors or pre-built bikes. If I wanted to install a motor on an existing bike, that’s when my questions start.

What do the frame and component manufactures have say? I’m assuming that all warranties are out the window. Like drilling holes for your GoPro mount.

The video of the installation makes it look easy. I would imagine it’s really not and also beyond an LBS.
— John

Dear John,
I haven’t asked, but I can’t imagine that your frame would still be under warranty if you shove a motor into it. At least you no longer have to drill holes in your seat tube down near the bottom bracket like the original Gruber Assist motor required!
― Lennard

Hemming cycling gear

Dear Lennard,
I am an on the short side of the average guy (5-foot-7) with a long torso and short legs — I ride a 50cm frame.

My problem is every pair of bibs or shorts is too long in the inseam. The gripper ends of the shorts always wind up right in my “knee pit” where the hamstring tendons stretch across, and it’s annoying.

I’d like to get my shorts hemmed. I tried a few local tailors, but while the shorts come out great initially, they must not sew the right kind of seam and the seams always fail. My guess is that to sew Lycra and other elastic material, you either need a special machine or a special kind of stitch that the average dry cleaner and tailor can’t do.

Can you recommend anyone that does alterations to cycling clothing that can do a high-quality job that lasts?
— Bill

Dear Bill,
Bouré Bicycle Clothing in Durango, Colorado charges a mere $20 for the work of shortening the inseam and return shipping. I have had Bouré lengthen the inseam on some shorts of mine (I have the opposite problem you do, and I hate it when my shorts hike up as I ride), as well as lengthen the torso and change the arm length on some skinsuits for cross-country ski racing. The quality of workmanship is outstanding; I still have and use most of these items years down the road. Additionally, Bouré offers custom-fit service on any item they make in-house (shorts, tights and knickers) for a 25 percent surcharge over the regular price.
― Lennard