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Technical FAQ: SRAM front derailleurs and foot-length differences

Our technical expert offers advice about SRAM front derailleurs, and shoes for those with differing foot sizes.

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

Dear Lennard,
Is it possible to control a rear derailleur of the eTap red AXS road bike series with the eagle AXS controller from the MTB line?
— Michele

Dear Michele,
Yes, it is. This combination works fine and makes for a great flat-bar electronic-shift road bike.
― Lennard

A SRAM front derailleur. Photo: Chris Wright

Dear Lennard,
Thanks for taking the time to respond to my inquiry about the tab in a SRAM front derailleur. In between my initial email and your response, I solved the problem. This was a problem I’d dealt with for several years, and it was beyond frustrating as you can imagine. Zack at SRAM (head of NA tech support) had been helpful to a point, but he refused to say anything about the tab I mentioned. His responses in fact usually trended towards getting me to consider upgrading to the eTap AXS system and to be honest he came off at times as not very knowledgeable about the product – especially the infamous tab.

Finally, what I did was Google the Force 22 derailleur and, voilá, one of the first images I found was one looking up into the cage – there was no tab. I knew Force and Red were compatible, so I found one of the Force 22 cabled FDs and ordered it. It arrived and was put on last Thursday and at long last, I have all 22 gears.

So, I did solve it, and as it is virtually impossible to find a picture of the inside of a Red 22 yaw FD cage, I have supplied you with the picture I took after it was taken off. The tab is actually not a tab, but a wedge that runs down the length of the interior of the plate and takes up at least half of the cage – thus why I could not get it to work properly. Again, no idea why this is this way, but I got it sorted.

Dear Chris,
No wonder you were having problems making that work! I have not seen a tab like that on any SRAM front derailleur before.
― Lennard

Dear Lennard,
I have been a VeloNews reader and also followed your columns for close to 30 years. I am writing to share some information with you about the column you ran five months ago about fitting cleats to different sized cycling shoes.

I have been on a bike in one form or another for the last 40 or so years. I haven’t raced in 20 years, but I still ride as much as I can. When I was racing back in the days of friction 5- and 6-speed shifting and into the early days of clipless pedals and STI downtube levers I worked my way up to a cat 2 USCF (pre-USAC) racer, and there came a day when racing was no longer fun for me anymore, so I walked away and never looked back except to the memories.

Racing and riding for me have always presented serious challenges because of my body, which is why I found your recent column very interesting. I have a 2cm leg length discrepancy — my Left leg is shorter than my right leg.

In addition, my left hip twists rearward. Lastly, my feet have very high arches and I have a 3-size discrepancy in the size of my feet. My left foot is a US 11.5 and my right foot is a US 8.5. In spite of all of this, I did reasonably well when I was racing. And now, in my non-racing riding life, I have done it by reading a lot, talking to a lot of people, and extracting and applying the information I had and needed to my own unique situation, and I never once had to spend tens of thousands of dollars on so-called “professional” fittings which used nothing more than cookie-cutter templates.

I have always used good cycling shoes starting with Shimano, and in the later years when I was racing, Sidi Genius shoes. While I have used just about every clipless pedal out there, I always favored and kept coming back to the first generation Look “Arc” pedals. I loved the wide, stable platform and the adjustability they offered. To address my leg length discrepancy, I first tried hard rubber or leather shims placed between the cleat and sole of my cycling shoes, but after several years I had to give that up due to the extremely painful hot spots the shims created especially on the ball of my left foot. After I threw the shims away, I just trained my body and mind to remember to drop my right ankle whenever I was riding, and this worked very well and still does.

The difference in the size of my feet was another conversation altogether and I finally came up with buying two sets of shoes in the same brand and model but different sizes. The last set of high-end cycling shoes I had were the Sidi Genius 5 in size 45cm for my left foot and 43 cm for my right foot, and once I got the cleat positions set and dialed in, I had minimal problems. In fact, I am very surprised that none of the so-called “doctors” and fit “experts” that you spoke with suggested this very, VERY simple solution. It looks to me like just possibly you have a bunch of posers working for you who like to justify their existence by dreaming up overly complicated solutions when a simple and very workable solution is right there in front of them which does the entire cycling community a huge disservice, but it is what it is…

The issue of different sized feet is much more widespread than the majority of people would imagine, and I would think that ANY maker of custom cycling shoes (and any other sport-specific shoe) would offer to make up different size shoes for one price as part of the service, but that is what I would do. Companies, when they think they have a lock on a market, tend to do some very stupid and greedy things that are not in the best interests of the industry and most definitely not in their best interest, but again it is what it is…

I would hope that you would share my letter and my experience with your readers, since it addresses a highly pertinent issue in the cycling and racing world, but I am also thinking you might not because my letter does not serve to promote the “Zinn” mystique. In any event, the information is there for you to do with as you will.

Dear David,
I don’t think any of the fit experts quoted in that column addressed two different size shoes because Mike said, “I have custom road shoes.” I assumed from that statement that Mike’s custom shoes are of two wildly different sizes to fit each foot and thus deal with his 32mm foot-length difference. I am guessing that the professional bike fitters who weighed in on Mike’s issue all figured the same thing. It is such an obvious solution to get a different size shoe to fit each foot that it never occurred to me that Mike would have had anything other than a proper-fitting shoe for each foot, and I don’t think it occurred to the four fit experts, either. I read Mike’s question as being: “I am wondering what the current thinking is on cleat position [for two shoes that have a big difference in size]”.

Regarding your comments about “so-called doctors and fit experts” and “a bunch of posers,” I beg to differ. I don’t think that there is anybody in the world with more experience fitting people on bikes than Andy Pruitt. He largely pioneered the melding of video motion capture and other high-tech technologies with medical diagnoses in bike fit. He personally set up riders like Tom Boonen, Peter Sagan, Fabian Cancellara, Vincenzo Nibali, Alberto Contador, and countless other champion cyclists on their bikes through the heights of their careers, and I will always welcome and appreciate his perspective on any fit questions in this column. Todd Carver and Jason Williams learned from Pruitt and continue to innovate further on their own. I don’t know about the basis for Chris Jacobson’s training, but the fact is that all professional bike fitters in the world have been influenced by Pruitt’s work in some way.

I appreciate your expertise in your own situation, and I imagine that there are lots of other riders out there with similar issues who have come to their own accommodations with them. I’m sure you can appreciate that, when I get a question like Mike’s, I can hardly be expected to know people personally with issues as rare as his, so I will always depend on the advice of experts in the field who have worked for years addressing difficult bike-fitting issues of innumerable riders.

As for your thought that I wouldn’t run your letter because it “does not serve to promote the Zinn mystique”, I’m flattered that you think that such mystique exists, and I’m not too concerned about it. I’m more interested in answering peoples’ questions as well as I can.
― Lennard

Lennard Zinn, our longtime technical writer, joined VeloNews in 1987. He is also a custom frame builder ( and purveyor of non-custom huge bikes (, 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.

Follow @lennardzinn on Twitter.