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Technical Q&A with Lennard Zinn: Electric shifting and eclectic componentry

By Lennard Zinn

The Dura-Ace electric drivetrain

The Dura-Ace electric drivetrain

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Electric D-A: Why not a little step instead of a big leap?
Dear Lennard,
Great review of the new electronic Dura-Ace in this month’s VeloNews. I have to say there have been a lot of comments about the “why?” of electric and it was nice to finally read an article that included a good reason — shifting under load that can’t be done with cable.

My question is this: Since the system is “smart,” in that it knows where the chain is on both the front chainring and rear cassette, how come the system doesn’t shift you into the next larger gear (in terms of gear inches) — so up to the big ring in front and down a couple of gears on the cassette — to make for a smoother application of power? It sounds like the system can put the chain where it wants. It would be cool if instead of the big jump you get when going between the chainrings, it would make it a step like any other on the cassette.
Jon

Dear Jon,
The Shimano folks answered this in Kona by saying that they did not want to make an automatic transmission; they simply wanted to make shifting easier and faster. I think that they felt that high-end consumers would resist not being in complete control of which gear the bike is in.
Lennard

Zipp crank with D-A 7900 drivetrain
Dear Lennard,
I am riding a Zipp Vuma Quad crankset (53/39) in conjunction with Shimano Dura-Ace 7800 series derailleurs and cassette on my Litespeed Ghisallo; performance is satisfactory. I am considering upgrading the shifters, front and rear derailleurs and cassette to Dura-Ace’s 7900 series. My question is one of compatibility. Do you know of anyone presently running this collection of parts? If so, have there been any problems or issues? I want to investigate the compatibility thing before investing money in the new parts, as I am very happy with the Zipp crank and want to leave that in the mix.
Michael

Dear Michael,
It will work fine. Spacings have not changed, and while the new hollow Dura-Ace 7900 chainring is stiffer (definitely a benefit with the super-powerful front shifting of the electronic group), I actually can notice very little shifting difference when I run mine with Ultegra or SRAM Red chainrings on it.
Lennard

Ultegra drivetrain with SRAM cassette
Dear Lennard,
I am setting up my road bike for a series of Audax-style endurance rides that involve some serious climbing. I use an Ultegra SL compact 50×34 crankset with an Ultegra SL 10 speed shortcage rear derailleur on the back. The chain is also Shimano Ultegra 10 speed.

I am investigating whether I can change the rear cassette to an SRAM OG 1070 11-28 to give some reasonable top end speed for the descents and have a supreme granny gear available for the big climbs after a very long day in the saddle.

Are the two brands compatible in this situation? And if so, is the Ultegra SL rear derailleur capable of taking the 28-tooth large cog?
Richard

Dear Richard,
Yes, the brands are compatible. And while the rear derailleur is not intended to handle 28 teeth, if you crank the b-screw in (against the tab on the dropout derailleur hanger), you can probably rotate the derailleur back enough to make it work without bumping along on the big cog.
Lennard

Protecting stored bikes
Dear Lennard,
I am storing two of my three high end bikes for the winter months (a ?2008 Cervelo SLC-SL and a Specialized Tarmac SL). The third I ?will be letting the Northeastern winter weather take its toll on ?while continuing to ride in the elements.

Is it prudent to apply a light ?sheen/coat of some type of oil or wax to the bikes — saddle, tires, chain, the carbon, the works — before storing them? My main ?goal is to preserve their bright color and shine, prevent ?rust and oxidation, and keep the tires from cracking and/or dry rot. Also, these bikes are stored hanging from the wall by their saddles.?Neither is over 15 pounds; both hang with their front ends maybe one and a half feet lower than the rear. Does?this put any undue strain on the frames?
Maurice

Dear Maurice,
If I had your concerns, I would cover the frame, fork, saddle, tires and bar tape with 303 Protectant That will protect the leather, rubber and clear coat. For the metal parts, I guess you could put oil all over them, but it seems like it will be gummy with dust next spring. I’d be more inclined to use soft car wax. And don’t worry about hanging the bike by the wheels; it won’t hurt your frame.
Lennard

Cleaning sealant out of tires, rims
Dear Lennard,
What’s the best way to clean old sealant out of tires and rims?
Bill

Dear Bill,
With Slime and other chopped-fiber sealants, use water. With latex sealants, peel it out with your fingers.
Lennard

Dear Lennard,
Not more than four miles after mounting up a new set of Hutchinson Python CX tires (tubeless-ready, although I am running tubes), I managed to get a small, sharp chunk of beer bottle jammed all the way through the tire, puncturing the tube. Upon removing the glass, I was left with a brand-new rear tire that had a 5mm cut just to the side of the center tread section. As it was mid-commute, I replaced the tube and hastily glued a patch on the inside of the tire. With the tire inflated, the hole pulls open a bit, and I can pull it open further with my finger. Is there any good way to salvage this tire and help it last as long as it should have in the first place?
Reid

Dear Reid,
Not really. You can patch it from the inside, which will help, but the glue and friction of the patch on the tire casing and tube are nowhere near as strong as intact casing cords.
Lennard

Feedback:
Here’s an easier method to obtain a TruVativ drive-side bearing to fit a SRAM crank in a Trek Madone with a Shimano crank on it.

Hi, Lennard,
Just wanted to send a note regarding the post on fitting a SRAM Red crank into a Trek Madone frame. We have received SRAM BB kits, but they sell so fast we have been consistently out of stock (we’re working to correct that). I will throw out another solution. In early development, we just pulled the non-drive bearing from a GXP cup. Rather than placing a heavy side load, the guys cut a couple of slots in the cup and the bearing can be easily pressed out and then used in the Madone. It still does require the special metal dust seal on the non-drive side, but tech services can provide that.
Tyler Pilger
Product Manager
Trek Bicycle Corporation

More feedback:
Don’t use a 10-speed crank with an 11-speed chain!

I read Lennard Zinn’s article [on running a 10-speed Record crank with Campy’s 11-speed chain] and thought that it was informative up until the point that I crashed on a ride just yesterday because of a chain-suck issue. In shifting from upper chain ring to lower the chain dropped in between the rings and stuck so hard that I lost control. My bike was professionally built and even my mechanic warned against using the 10-speed crank. How could someone that is so knowledgeable even think to tell people that this is okay? I spoke with my mechanic yesterday afternoon and he has informed me that any components that are damaged are not covered under warranty since I didn’t use the 11-speed cranks. I knew I should have waited the extra two weeks for my shop to get the crank I wanted in stock. Now besides buying the crank I need to buy a new chain and possibly a rear derailleur. Not to mention the road rash (ouch). I have lost faith in VeloNews and its staff.
Frank

Dear readers,
With this feedback, I have to officially recommend against using an 11-speed chain with 10-speed chainrings, at least Campagnolo (and Fulcrum) ones. And Campagnolo is very clear in its warranty policy that nothing is covered unless the entire 11-speed group is used together — no substitutions.

However, I’ve been riding for months on 10-speed cranks with the 11-speed Super Record group, and I’ve never had any problem. I’ve used it with both SRAM Red chainrings and Shimano Ultegra SL chainrings without a hint of shifting hesitation, much less getting stuck. And as you may have read in my article on Shimano Di2 electronic in the current print edition of VeloNews, I shifted this combination under extreme loads repeatedly, trying to duplicate the performance of the electronic front derailleur with a cable-actuated one.

As I feel is my duty, I will continue to try cross-compatibility issues, since lots of readers ask me about them. They expect an answer other than the one the manufacturer would give, which is of course always to the effect that all of the parts need to be used together as a system.

I avoid advising people on setups I have not tried, but I’ve tried this one pretty thoroughly, albeit not with Campy 10-speed chainrings. Similarly, when the change from 9-speed to 10 came, I used 9-sped cranks on 10-speed groups interchangeably for years and never had a problem.

As I have switched Campy, SRAM, and Shimano 10-speed cranks all around on each other’s 10-speed groups for years without problems, I would not have expected that it would have mattered which brand of 10-speed cranks you used with the 11-speed chain, but perhaps it does. I have to say that I’m very surprised. The chain is 0.5mm narrower than the Campy 10-speed chain. That’s not much.

I remember hearing once about a chain jamming between chainrings when I was racing —I think it was at the 1981 U.S. nationals time trial in Bear Mountain, New York. Somebody told me that a top rider, whom I had expected to do very well in the TT, had jammed his chain between his chainrings; he had been using a 7-speed chain on a 6-speed Dura-Ace Dyna-Drive crank.

I was also on a Shimano-sponsored team, racing on Dura-Ace EX and AX, but I was still using the same 180mm Campy Super Record crank that I’d used for 5-speed and 6-speed (because Shimano did not offer a crank longer than 175mm back then). Those were some big differences in chain widths as the widths started coming down back then, but nobody thought twice about mixing cranks from different generations with them, and that’s the only incident I remember of somebody jamming a chain.

Shimano’s spacing between cogs has narrowed from 3.70mm for 5- and 6-speed, to 3.10mm for 7-speed, 3.00mm for 8-speed, 2.56mm for 9-speed, and 2.35mm for 10-speed. When SunTour introduced narrow Ultra-7 freewheels in the early 1980s, Shimano countered with wider freehub bodies that fit seven widely spaced cogs (at 3.70mm apart) and the wide 6-speed Shimano chain. But at the time, we all started using Sedis Sport chains, because they were cheap (four bucks!), they worked well, and, most importantly, they were narrow and worked with any of the new 7-speed narrow systems. And it never occurred to any of us at the time to switch cranks because we were using that chain. Sedis merged with Maillard, which was acquired by Sachs, which was purchased by SRAM, and so the Sedis chain lives on!

Campagnolo’s 5.9mm-wide 10-speed chain (its first-generation 10-speed chains were 6.1mm wide) allows 10 cogs to fit in the same space that used to only accept nine with the wider 9-speed chain and cogset, and now the even narrower 5.4mm wide 11-speed chain allows 11 cogs to fit in that same space. The thickness of the spacers on either side of each cog has come down as far as 2.2mm with 11-speed, whereas the width of each chain roller and thickness of each cog has stayed the same. The tooth-to-tooth distance on Campagnolo 9-speed is 4.55mm, 4.15mm on Campagnolo 10-speed, and 3.9mm on Campagnolo 11-speed. Chainring tooth spacing is hard to measure, because of the height difference between the two rings, but the spacing between cogs is only 0.25mm less on 11-speed than on 10-speed! That’s not much.

One final note: When I told Dave Batka, the president of Wheels Manufacturing, about this jammed chain, he said: “I hate to say it, Lennard, but I can’t believe this at all. I’ve got 600 miles on my new 11-speed chain with 10-speed chainrings and it has never even come close to jamming in between the chainrings. You may quote me, if you wish.”

So there you have it, from both sides of the debate. Forewarned is forearmed.
Lennard


Technical writer Lennard Zinn is a frame builder (www.zinncycles.com), a former U.S. national team rider and author of numerous books on bikes and bike maintenance including the pair of successful maintenance guides “Zinn and the Art of Mountain Bike Maintenance” – now available also on DVD, and “Zinn and the Art of Road Bike Maintenance,” as well as “Zinn and the Art of Triathlon Bikes” and “Zinn’s Cycling Primer: Maintenance Tips and Skill Building for Cyclists.”

Zinn’s regular column is devoted to addressing readers’ technical questions about bikes, their care and feeding and how we as riders can use them as comfortably and efficiently as possible. Readers can send brief technical questions directly to Zinn. Zinn’s column appears here each Tuesday.

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