Bikes & Tech
Photo: Dan Cavallari | VeloNews

Tech FAQ: Crank-spider tab thickness, tire specs, IT bands

Lennard Zinn answers a variety of questions in this week's column.

Have a question for Lennard? Please email us to be included in Technical FAQ.

Drivetrain update

Dear Lennard,
I have an older road tandem with a 3×9 drivetrain that has sat idle for a long time. I would like to update the drivetrain to a 2×11 setup. The square taper arms will allow me to replace the BB to a shorter spindle to move the crank arm more inbound when the inner ring is removed to get the correct chain line. My question is regarding the spacing of the chainrings as they mount to the spider, or in other words the width of the tab that the rings mount to. Is there an issue with installing 11-speed rings on an older crankset? What is an acceptable distance that the chainrings should be spaced apart?
— Bart

Dear Bart,
I don’t know the brand of your cranks, but I would bet you are not going to have an issue.

As you may know, we machine cranks ourselves. I used to worry about tab thickness with increases in the number of rear cogs, as we started during the era of 9-speed cassettes and are now dealing with 11- and 12-speed cassettes. I measured the tab thickness of lots of cranks and was surprised to find that they don’t tend to vary between 9-speed, 10-speed, and 11-speed cranks. We settled on making the tabs on our cranks 3.55mm thick, and I know from personal experience that if your tabs are anywhere in the 3.55-3.65mm thickness range, you won’t have a problem with using it as a 2×11.
― Lennard

More on tire width and pressure

Dear Lennard,
I read the article about gravel tire width and pressure with great interest until I noticed the 140-pound weight of your test rider. [Ed. note: this was in the VeloNews print magazine; here is an earlier article from the magazine on pressure alone.] I’m 100 pounds heavier than that and wonder what you think would happen to your results with someone my size?
— Lee

Dear Lee,
The tire widths that work best on gravel roads would go up with your greater weight. And the optimal air pressures with those tires that worked best would also go up. Without doing that specific testing, I cannot quantify it any further.
― Lennard

Feedback on nagging IT band pain

Dear Lennard,
I just read the question from the guy with IT band issues. I had a severe issue with this decades ago and what fixed it, permanently, was 1 minute of a stretch called the “pretzel” every night. Seriously, in a week the condition was resolved. You lie on your back, cross your legs with knees bent, and pull your knee with both hands toward your sternum, same on both sides. Might want to suggest this to everyone. Free and it worked for me.
— Jonathan

Dear Lennard,
I suffered from debilitating ITBS for years and did innumerable sessions of stretching, painful A.R.T. [Active Release Therapy], massage, and enough rest to drive me crazy. But when a friend put me onto the research of Dr. Reed Ferber, director of the Running Injury Clinic in Calgary, Alberta, I quickly solved the issue using a very simple protocol. With relatively minimal maintenance, I have been ITB pain-free for the past half-decade.

The bottom line is hip stability. Cyclists and runners generally have terrible hip stability because of the biomechanics, and primary movements, of both sports. Now I do a series of side-to-side squats/lunges in a plyometric style of movement, and when starting out it’s brutal because of weak glutes. But it works. Some of Dr. Ferber’s research and protocol is published in this article.
— Jamie

Dear Lennard,
I was having a lot of trouble with really tight IT bands, and I found this stretch on YouTube. For me, this literally worked after 30 seconds or so, and after doing the stretch a few times a week for a couple of months I haven’t had another problem.

I also tried bands and rollers, but I don’t need to do them anymore when I use this stretch.
— Rob

Dear Lennard,
Years ago I started to have knee pain and, after some false starts, I finally narrowed it down to IT Band tension. The first two stretches in this video are the
 ones I use. They can be done anywhere — I’ve stopped in the middle of a ride and leaned against a telephone pole instead of the wall used in the video. In my case, knee pain relief is almost instant after a few rounds of stretching each side.
— Doug