Technical FAQ: 12-speed gearing options; cassette compatibility; anticoagulants
With my age and market basket of chronic conditions, I have gravitated to longer and longer gearing on my road bike. For now, it’s a Force 1, 42 x 11-36 11-speed. I can get an insignificantly easier gear with a 46 x 11-40 11-speed. Otherwise, they are virtually identical. That pretty much maxes out the long cage derailleur. I’d have to go electronic to go back to 2x, so I don’t consider that an option.
So, I’m curious if there is any reason to favor the larger chainring? I understand that larger rings have less friction, but I wonder if the longer, wide/narrow teeth change that at all.
In the 2019 VeloNews Gear Issue, I wrote up the results of a test we recently did of exactly this — the frictional drag of 2x vs. 1x drivetrains. The article is well worth a read, and I recommend picking up a copy.
One result is that the bigger the chainring, the lower the drivetrain frictional losses due to reduced link articulation (folding). There is no question that you will go faster for the same pedaling output (or use less energy to go the same speed) with the 46 x 11-40 than with your current 42 x 11-36. If you interpolate from the graphs I ran in that article, you can even get an idea of the magnitude of the friction reduction.
The article, in general, goes through the data showing that the frictional drag is greater on a 1x drivetrain than on a 2x one. This is primarily due to cross-chaining, but it is also due to the discussion above — smaller cog and chainring sizes to achieve a given gear ratio.
Your switching to the bigger chainring does nothing to reduce the cross-chaining losses, and the narrow-wide (NW) teeth don’t save you any drag, either. Previous testing by Friction Facts shows that NW teeth create no more friction when cross-chaining than do standard, uniform-thickness (i.e., 2x or 3x) chainring teeth. This is because every single tooth on a narrow/wide-tooth chainring pulls the chain over the same amount; it moves narrow and wide chain links laterally the same distance. With a standard chainring working at the same cross-chain angle, the teeth don’t pull over the wide chain links, but every other tooth pulls the narrow chain links over twice as far as each tooth on an NW pulls a chain. It ends up being a wash, friction-wise.
I’m considering the new SRAM AXS, but my Bontrager wheelset is not XDR compatible (but a Campy freehub body is available). Any idea on whether a Campy 12 cassette will work with the new SRAM group? I know the range will be different — no 10T, obviously.
I know SRAM wants to push its expanded range philosophy with the 10T cog, but I can’t help to think that plenty of other folks would love the wireless setup but with more typical cassette choices. If Campy 12 isn’t good, I’ll be curious to see if an aftermarket company offers a conversion cassette. Or I am just being a curmudgeon who doesn’t want to buy new wheels.
Here at Zinn Cycles, we have yet to get any 12-speed Campagnolo cassettes, so I have not tried mixing any SRAM and Campagnolo 12-speed components.
That said, I expect a SRAM 12-speed chain would work on a 12-speed Campagnolo cassette. This is based on my experience with 11-speed cassettes and chains. I have found that interchanging 11-speed cassettes between SRAM, Shimano and Campagnolo creates no shifting problems on 11-speed drivetrains from any of those companies. Furthermore, 11-speed chains from Wippermann and FSA also work fine on SRAM, Shimano, and Campagnolo 11-speed cassettes.
Given that the space between cogs tightened up so much in going from 10-speed to 11-speed that the spacing differences between manufacturers disappeared, I don’t expect any new spacing differences between manufacturers with 12-speed. There simply is not enough room in there to do anything but minimize the space, thus all ending up with the same spacing.
Some feedback from doctors regarding blood anticoagulants
I am concerned about some of the opinions voiced in the recent discussion about blood thinners. In particular, Phil opined that blood dopers were all anticoagulated, but we don’t know what was in those bags, and heparin does not have a very prolonged effect. His argument that blood doping may prevent DVT and that the racers were all “loaded with blood thinners” is likely wrong.
Regarding vitamin K concentrate, that approach may be helpful, but oral vitamin K does NOT work right away. So, the idea that you “swig, and your blood will clot” is incorrect and potentially dangerous. If there is a serious injury that may cause bleeding, a faster-acting agent (that must be administered in a medical facility) may be needed, and oral vitamin K should not be assumed to be sufficient in all cases. Giving too much vitamin K orally may also make it difficult to restart anticoagulation afterward because it antagonizes the effect of warfarin for several days or longer.
The statement, “I would think compression socks make the chances of getting DVT worse, not better” is speculation, and the available evidence suggests that compression stockings are either helpful or harmless, but do not increase the risk of DVT.
Calling oral contraceptives a “massive risk” for DVT is an overstatement. They increase the risk, but it is still low, especially compared with the medical risks (including DVT) of pregnancy. That said, there are multiple options for contraception, and women should discuss the merits and risks of alternatives with their gynecologist.
— Jonathan Blum, M.D.
Dear Dr. Blum,
Thanks for your letter. As I am not a doctor, and this column is not vetted by doctors prior to publication, we depend on people like you with the knowledge to help us separate the wheat from the chaff. Thank you for doing that.
I read the great emails from the readers; I did not know so many [people] ride on anticoagulants, a.k.a. blood thinners.
I would like everyone to know there is a procedure called the Watchman. This is an implantable cardiac device for patients with atrial fibrillation who require blood thinners but who are not good candidates for anticoagulation, i.e., cyclists and the elderly. It is not for people with DVT or pulmonary embolism.
It is a plug inserted into a part of the left atrium called the left atrial appendage. This appendage is where most of the blood clots form, as there is inadequate blood flow during atrial fibrillation leading to clotting in that appendage. The goal is to thin the blood so that clots will not form in the appendage and hence won’t break off and travel to the brain or any other organ.
Usually, an Interventional Cardiologist or a Cardiac Electrophysiologist can implant a Watchman device via the femoral vein. Of course, there are procedural risks, but we always have to consider the risk of a head injury on any anticoagulant, reversible or not.
If the readers are worried about [an anticoagulant with] a reversible agent, Pradaxa has a widely available and immediate acting antidote called Praxbind. I have seen it in action, it works quite quickly, and it is widely available. Some of my patients on Pradaxa have required urgent surgery, and there was no bleeding at all when Praxbind was given. The reversal agents for Eliquis and Xarelto are not as widely available as of yet. More information and options that we all have, the better decisions we can make for our own health.
— Dr. James Connelly
Dear Dr. Connelly,
That is new information to me about the Watchman and much appreciated. Thanks.