Technical FAQ: Chain optimization for recreational riders; pressurizing tires; denatured alcohol in California
In this week's Technical FAQ, Lennard Zinn answers questions on tire pressure and chain optimization.
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This report filed June 14, 2022
I have been reading with interest the thread re: chain cleaning, friction, etc. https://velo.outsideonline.com/gear/road-gear/technical-qa-with-lennard-zinn-cleaning-solvents-prior-to-chain-waxing/ . My question is this: does it really matter for the vast majority of us? I love drilling into the details as much as anyone, but after a 120-mile ride yesterday (which I started with an immaculately clean and well-lubed chain), the chain was coated in the dirt and grime typical of any ride. Surely, after even a few miles, this real-world dirt will obviate any incremental gains realized by obsessively cleaning the chain (which I do) and obsessively coating it with special, expensive lubricants (which I also do)? I’m not suggesting we all use WD-40, but, my OCD tendencies notwithstanding, does following complicated protocols result in appreciable gains in efficiency by the average recreational cyclist (which I very much am)?
This is an entirely earnest, sincere question, by the way: I am genuinely curious, and not trolling in the least.
Also read: 30 chain lubes lab tested for efficiency
On a 120-mile ride, it could make a measurable difference in time and possibly one in fatigue as well.
The cleaned and hot-waxed chain will not pick up that dirt that will slow your chain down. It will start out by saving you on the order of a watt at the beginning of the ride. By the end of the ride, the hot-waxed chain won’t have slowed down, since it won’t pick up any dirt. On the other hand, the conventionally-lubed chain will have slowed down, so you could be saving 2-3 watts by the end with a cleaned and hot-waxed chain.
Riding at around 20mph with 200-watt power output will result in about 0.1mph speed reduction if power output decreases by 2 watts. That’s about two minutes slower over 120 miles.
If you’re riding with a group, having to put out an extra watt or two might not break the bank, and you might then finish with the same group, at the same time you otherwise would have. In that case, going to all that trouble would net you nothing. On the other hand, if you are barely hanging onto that group, having to put out an extra watt or two might make the difference between being dropped or not, and if you get dropped, you could expect a large time loss and much higher fatigue at the end.
Also read: The Who, What, Why of Chain Lubes
A likely simple one for you that has had me curious for a while. Many hookless wheels specify a max PSI of say 72.5 PSI or so usually.When mounting some new tires last week I wondered how using a charge pump and shooting 160PSI into the rim doesn’t damage the wheel or cause other issues? Is it because it’s only a very short acute burst until the bead is seated, or is there some other wizardry I’m unaware of here? Evan
Even though the air in the charged pump may be at 160psi, when it blows into the tire, it is no longer at that pressure. The volume of the tire may actually be similar to the volume of the charge cylinder on the pump. If the volume of the tire is equal to that of the cylinder (which is at 160psi), when the air is released from the cylinder and it rushes into the tire, the pressure in the charge cylinder and in the tire would equalize at 80psi.
Also read: Technical FAQ: Minimum tire pressure and more
Regarding this column: I live in California and just purchased denatured alcohol a couple of weeks ago. Anyone looking for denatured alcohol just needs to visit a marine store and purchase fuel for an alcohol stove.
I spoke with Shimano USA regarding using a Shimano 50/36 Chainring combo, which they were dead set against, won’t shift correctly etc… and told to only use the stock 50/34 combo and not to deviate from the official combos. I don’t like the large gap between the 50/34 and much prefer the 50/36 gearing and in fact it shifts just as good if not better and faster than the stock set up. So here’s my questions How do pro teams set up the unusual combos they run? I’ve seen mention of 54 or even 55. Does Shimano produce matched Chain rings for these combos? Are there special race only E-TUBE programs for these mismatched set ups? Thank you for all the tech information you share. Scott
I haven’t been to the Tour or other major European race in a long time, so my information may be a bit out of date. Back when I was going to those races, however, mechanics were on their own to make the gear combinations the riders requested. I doubt that has changed. I’m willing to bet that those team mechanics have to use non-Shimano chainrings and will have to adjust the Di2 shifting themselves.
Lennard Zinn (https://velo.outsideonline.com/byline/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 Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.”
He holds a bachelor’s in physics from Colorado College.