In Technical FAQ, Lennard Zinn fields more inquiries on cross-compatibility and rebuffs a suggestion that electronic is cheating
We continue to receive inquiries on 10- and 11-speed compatibility and we’ll take a look at the issue from a number of different perspectives this week, including one rider’s plans to purchase a power meter before upgrading to SRAM 22 and another’s inquiry over freehub manipulations. First to a couple of unrelated questions tying back to previous columns.
Check my big-guy bike dimensions for wobble control
Thank you, thank you [for the recent column on bike design for large riders]. This August my bike went into a shimmy at 50 mph on a descent, and while I managed to cut the speed by half before I dumped it, I woke up with paramedics around me and spent a night in the hospital. Luckily, mild concussion and a right side that looked like I’d taken a cheese grater to it was the sum of my injuries.
But this isn’t the first time the bike has shimmied on me (although it’s not common). I’m 6-foot-3 and 160 pounds, so not a huge rider, but still, those are long tubes.
I had a very knowledgeable bike buddy design my frame for me and had Calfee build it (from Tetra tubing). My concern is that my average-height friend wouldn’t know as much about long-tube bikes as you do (sure wish I’d run across you earlier!) and may have designed a bike that is even more likely to shimmy due to my height than normal. Here are the specs:
Seat tube: 61cm
Top tube: 62cm
Seat tube angle: 74 degrees
Head tube angle: 73 degrees
Head tube: 26.5cm
Fork rake: 44mm
My question is, does anything about the geometry of this bike lend itself more to shimmy than usual? I understand that if you say no, you’re not saying that the bike shouldn’t shimmy. You can’t promise anything, I get that. But you’re obviously so knowledgeable, perhaps you can tell at a glance if there’s a danger sign.
The specs are fine in terms of effective dimensions. But since you don’t say it specifically, I assume it’s got a level top tube that meets near the top of the head tube. If so, that makes the seat tube and seatstays unnecessarily long and the top tube a bit longer than if it were angled up. It’s not that it’s wrong, but given the right rider and the right conditions, it’s more prone to shimmy than if it had a few changes while maintaining the same relative positions of the saddle, pedals and handlebar.
From plenty of personal experiences like this back in the early 1980s, I have been meeting the top tube lower on the head tube for over 20 years to shorten the seat tube and seatstays. You still need that head tube length to get your bars where they need to be, but if it’s reinforced, you don’t need the top tube to be up there so high to meet it at the top. Additionally, sloping the top tube adds even more rigidity by shortening the top tube as well as further shortening the seat tube and seatstays.
Without doing those things, to stiffen up such long tubes with so much separation between them, the tubes should be increased in diameter.
Isn’t electronic shifting the same as using a motor?
You have recently been suggesting that electronic shifting actually saves (rider) energy in certain cyclocross situations. If this is so, is it fair to utilize an external power source (battery) to deliver energy to the overall effort of racing, regardless of how small that is?
Since battery power doesn’t actually propel the bike, it seems that the line is clear to me. I’ll let others weigh in on the ethics if they so desire. (One place to do that is on our new Google+ page —Ed.)
I have a buddy who races with battery-powered electric gloves on extremely cold days. Certainly those reduce his effort to shift and brake on days when his hands would otherwise be numb and less functional, but I think it’s a smart choice rather than an unfair one. And I see no reason to limit battery-powered lights for night racing. If the rider is willing to lug a battery around that doesn’t drive the rear wheel, he or she ought to be able to do it.
How should I set up a Quarq/11-speed upgrade?
I’ve been saving my pennies for a Quarq crankset to add to my SRAM Force 10-speed group and am about ready to purchase. One day in the future, once I finish graduate school, I hope to upgrade to Force 22.
Will a 10-speed Quarq crank work on SRAM’s 11-speed group? Is it simply a matter of changing out rings or are there other spacing issues that would negatively affect performance?
Or can I buy a new Force 22 Quarq crank and use 10-speed rings on it with my current set up?
I’ve written at length about compatibility between 11-speed groups, and have answered reader questions about 10- and 11-speed compatibility, but I went to SRAM for this one.
Answer from SRAM/Quarq:
Ten-speed chainrings can be installed on an 11-speed crank, just as 11-speed chainrings can be installed on a 10-speed crank. The spiders are identical. However, all of our groups are designed to function as complete groups, so if a 10-speed crank is installed in an 11-speed group or vice versa, we strongly recommend changing to the appropriate chainrings. Ten- and 11-speed should not be mixed. Our 22 groups actually have the chainrings slightly farther apart than our 10-speed groups, in order to ensure that all cogs can be safely reached in the small ring, and the chain and front derailleur are specifically designed to work with that gap. Running a 10-speed chain on 11-speed rings or an 11-speed chain on 10-speed rings could cause chain jams or derailments.
So yes, purchase the power meter of your choice, knowing that it will still be usable when you go 11-speed, but make sure you have 10-speed rings on it when you run it with a 10-speed group.
Public relations specialist, road and cyclocross, SRAM/Zipp/Quarq
FSA weighs in regarding 10/11-speed chainring compatibility
I recently read your bit on 10/11-speed chainring interchangeability. We have actually revised and optimized our rings from straight N10 to N10/11, and don’t consider the N10 to be forward compatible to 11-speed. The reason we take this stance is that, while the spacing is similar, 11-speed front derailleur springs tend to have a lighter return.
Since the spacing is similar, you may have good luck running the N10 rings with 11-speed systems, but I wanted to explain our point of view as well.
Tech manager, Full Speed Ahead
Aren’t 29er wheels too big for 700C tires?
In response to your column on converting 29er wheels for cyclocross, isn’t a 29-inch mountain bike wheel a little too large for a 700C ’cross tire (the 29er tire has a slightly larger diameter bead than a 700C)? I tried it a couple years ago and seem to recall I couldn’ t get my ’cross tires to seat on a 29-inch wheel (Bontrager Race X Lite tubeless-ready) without a flat spot.
No, the bead seat diameter is identical. A 29er rim is a 700C rim. Same thing. The rim is wider, but as you know, road rims are going that way these days as well.
More compatibility information
I just got finished reading your column from Oct. 30 about converting 29er wheels for CX disc use. Quite useful this time of year, especially for the CX racer who just spent his whole budget on a new 11-speed race bike!
I do have to point out one small error in regards to your comment on DT Swiss hubs with 11-speed freehub bodies. As you point out, our J-bend QR mountain hubs are 100-percent compatible with 11-speed road drivetrains. A simple freehub body and endcap swap is usually all that is needed. However, there should be no need to re-dish a wheel that goes from SRAM/Shimano 10 to Campy 10/11 cassette compatibility. The only time you should need to re-dish is when you go from SRAM/Shimano 10-speed or Campy 10/11 speed to Shimano/SRAM 11-speed (or vise versa). In that case, you should need to pull the wheel 0.5mm back toward the driveside after swapping.
OEM sales support, DT Swiss, Inc.
Thought I would add a bit of compatibility info. I have just fitted a Shimano Ultegra 6800 rear derailleur with Campagnolo Chorus 11-speed Ergopowers, and the front derailleur is Campagnolo. So I would note the following:
1. Campagnolo and Shimano 11-speed are completely interchangeable (shifters, cassettes, etc.);
2. the Shimano 11-speed chain is just a 10-speed chain; there is no difference that I can see;
3. I am running a 10-speed double SRAM crank, and it works fine with 11-speed (I don’t think there is any real difference); and
4. I have 11-speed wheels but the Shimano 11-speed cassette fits straight onto my Mavic Aksium, which is Shimano 9/10-speed (they always needed a spacer, so no new wheels needed if you are running Mavic!).
I think as Shimano has increased the cassette width, it has allowed chain and cranks to remain nice and compatible.
I’m surprised at the Ultegra rear derailleur working with the Campy shifters. I’m interested to try that. I’ve written here about the Mavic hub compatibility as well as the 10-speed and 11-speed chainring compatibility.
As for the chains, there is a width difference between 10- and 11-speed chains. I haven’t tried it, but I can imagine that some 10-speed chains may work on 11-speed cogsets. I do have a 10-speed SRAM master link on the 11-speed Campy chain on my disc cyclocross bike, and although it is obviously wider than the chain, it never hangs up or makes any noise going through the cogs.