Gear

Technical Q&A with Lennard Zinn

Dear Lennard Zinn;I am looking for a recommendation for a good chain to use with a '95 Campy Chorus 8-speed EXA-Drive system. The cassette and chainrings are previously unridden, but a new SRAM PC-58, which I believe is intended to be an 8-speed chain, runs a little rough. Any better suggestion? --Bill Veihmeyer Dear Bill;I have found that 8-speed Shimano chains always worked great on that system. --Lennard A mystery skipDear Lennard;I have Campy record 10-speed on two of my bikes, the chain started skipping on one of them, so I figured it was the cog set, I put that same wheel on the

By Lennard Zinn

Dear Lennard Zinn;
I am looking for a recommendation for a good chain to use with a ’95 Campy Chorus 8-speed EXA-Drive system. The cassette and chainrings are previously unridden, but a new SRAM PC-58, which I believe is intended to be an 8-speed chain, runs a little rough. Any better suggestion? –Bill Veihmeyer

Dear Bill;
I have found that 8-speed Shimano chains always worked great on that system. –Lennard

A mystery skip
Dear Lennard;
I have Campy record 10-speed on two of my bikes, the chain started skipping on one of them, so I figured it was the cog set, I put that same wheel on the other bike and it also skipped on that bike.

I took it in to a local shop and they replaced the chain and did a setup on it. I got it back and it still skips.

I put the other wheel set on the bike that didn’t skip before and now it skips. The third and fourth cogs from the left are the only ones skipping and they do it on either chainring.

I have a hard time believing that both sets of cogs went bad at the same time.The bikes are both Colnago. I remember this happening a few years ago on a bike and I think maybe the chain was too long.

Anyway I am at a loss and so is the bike shop.

I hate to start spending a bunch of money on parts I don’t need if the chain needs to be adjusted. I have already spent a bunch of money just on the bikes. I ride around 200-300 miles a week weather permitting. –Danny

Dear Danny;
Well, my first guess would be that one chain was worn out and hence the space between rollers had expanded, thus only contacting one tooth at a time, rather than spreading the load over a number of cog teeth (or there was a broken roller in the chain).

Either way, it would wear out the cog. Then, if you put on the other wheel and rode it awhile, that chain would wear out some cogs on that wheel as well. When you put on a new chain, it would now skip on both wheels because the cog teeth are now hook-shaped and the flanks are spaced too far apart.

But you should only replace your cogs and chains if you are certain that your derailleur adjustment is right on (your derailleur hanger could also be bent and need alignment). The chain also needs to be the proper length. With a double, this means having the jockey wheels vertically about one another when the chain is on the big ring and the smallest cog.

If it is the smaller cogs not attached to the carrier, you can replace them singly, and any bike shop can order them.

There are tools to check chain wear and cog wear–Rohloff makes some particularly easy-to-use ones.

If you run a good chain on a bad cogset, you can wreck it pretty fast, and then it won’t work on your other cogset.

Your shop should be able to advise you on chain length, if the cogs and chain are not worn out, or look in my road bike maintenance book for more tips. –Lennard

A mystery clunk
Dear Lennard;
Last year I took my relatively new Festina M4 on a tour. After I returned home and reassembled it, there’s a loud noise “clunk” coming from the handlebars or stem whenever I hit a bump. It’s not the original stem that I changed it out for a shorter one with a higher angle. My stem is a Ritchie and I’m not sure about the handlebars. They came with my bike. All the components are Campy Record (I think, the more expensive one).

I’ve taken the bike in for checks, and they found nothing. What do you think? –Noel

Dear Noel;
I think it is a loose headset because your new stem’s steering-tube clamp is not as tall as that of your old stem. When you tighten down on the top cap, it bottoms out on the steering tube before it pushes the stem down enough to preload the headset. Put one more spacer above or below the stem and try again. –Lennard

Moving up to 7-speed
Dear Lennard;
I have an old 6-speed road bike with Shimano 600 components. I put a new chain on which made it worse…so I took it in to the local bike shop for a new freewheel and cassette. They didn’t have the same configuration (12/24). They only had 14/24. Are there parts hard to come by now? I thought I saw a 7-speed freewheel with something similar…so I asked the guy if it is possible to fit one of those on to my bike. He said it would be too wide…is this true?

I thought for a 6 and 7-speed it wouldn’t matter. I am thinking I should have gone to a higher end road bike shop. –Stewart

Dear Stewart;
You are right. 6 and 7-speeds both have the same hub overlock spacing (the inside-inside measurement from one dropout face to the other) of 126mm, although the spacing between cogs will depend on make and model. You may need to move spacers from one side of the hub to the other and re-dish the wheel to get cog clearance with the 7-speed freewheel, however. –Lennard

Resurrecting an old debate
Dear Lennard;
Would you please be able to tell me the difference between Clincher and Tubular Tires? Also which do you think is better? –John

Dear John;
Give the format, it’s hard to go into great detail here, but I do go into all of this in the July 2002 issue of Inside Triathlon magazine, as well as in the VeloNews Road Season Journal from 1999, if you still have either of those. I describe how to glue them, etc. in both of those articles as well as in “Zinn and the Art of Road Bike Maintenance.”

A tubular is essentially the same as a clincher, except it has no bead and has the tube sewn inside. It is then glued onto a rim that has no bead hook, just a small curve on top for the underside of the tire to fit into. With similar quality construction, the tubular tire and rim will be lighter and will hold more pressure. It will also be more hassle to mount. You make the choice of which is “better.” –Lennard

Did Beloki have his Hed on straight?
Dear Lennard;
Just wondering about the Hed “Kona Coast” you guys identified in the VeloNews gear review. You stated that Beloki used it during the Vuelta. This is not the case, if you look closely the wheel Beloki uses with the three holes clearly has a Campy logo and is white, Olano used this same style of Campy wheel during the 1999 Vuelta except it had four holes in the front.

Hope this clears things up, otherwise awesome job, I keep an eye on your column and it helps quite a bit especially with all the info/feedback on Campy stuff. –Maurice

Dear Maurice;
As is often the case, what you see on the pro racers’ bikes is not what you get. I asked Hed about it, and here is the answer. –Lennard

Answer from Hed

Lennard;
Nope, Maurice is wrong on this one. The wheels were painted with the Campy logo to avoid hassles. The four-hole ones are Campy.
Andy Tetmeyer
wheel guru, Hed Wheels

Another case of mistaken identity… or labeling
Dear Lennard;
I was watching OLN’s coverage of the 2002 Tour de France time trials. Kind of hard to tell but the bike that Laurent Jalabert was riding looks a lot like a Cervelo. The seat and downtube looked much smaller in profile than the tubes on the “regular” Look time trial machines and the seat tube seemed to have a distinct bed in it to accommodate the rear wheel – much like the Cervelo does. Would love to know if Jalabert was in fact riding a rebadged Cervelo. –Chris

Dear Chris;
It is and he was. It is a Cervelo P3. Apparently he and the team were happy with the bikes because this year, CSC, sans Jalabert, is using Cervelo exclusively –Lennard

How about I trim my toes?
Dear Lennard;
I recently purchased a 2002 Jamis Nova cyclo-cross frame, built it up and discovered that when I turn corners and have my cranks level the front wheel hits my toes. I have never had this happen with any of my other bikes. I normally ride a 55cm frame, but was told that I need a 53cm for the cyclo-cross bike because of the higher bottom bracket. The toe rub is quite annoying, am I riding the bike wrong or is it because of the frame size? By the way my friend rides a 53cm Litespeed Arenburg and experiences the same problem. Any Solutions? –Brandon

Dear Brandon;
Independent of the frame, it is a function of your shoe size, tire size, crank length and cleat position — the latter three being things you can change. As for the frame and fork, toe overlap is dependent on the top tube length and the seat and head angles as well as the fork rake. A short top tube, shallow seat angle and steep head angle and short fork rake all bring the wheel closer to the crank. The fork is the only thing you can change without getting a new bike, and most aftermarket forks have rakes within only a few millimeter range. –Lennard

What is the one and true method, oh wise one?
Dear Lennard;
I am a young mechanic at my local shop. Last week in the shop I was asked to demonstrate the process of lacing a wheel to the owner and senior mechanic, which I did based on the instructions in the 2nd edition Mountain Bike Maintenance which I copied from the book. After receiving their comments and reviewing several other sources I have found that there are other methods to building a 3x wheel resulting with the same end product. I do not doubt your credibility nor that of the people I work with.

The question in point is, is it possible to have more than one method of lacing a 3x correctly? –Frederic

Dear Frederic;
Yes, there is more than one way to skin a 3-cross cat. You can approach it a number of different ways and come out with the same end product.

I test the methods I describe in my books constantly by having students build wheels following the instructions. As long as they follow the directions to the letter, they come out with a three-cross wheel with the pulling spokes to the outside and the valve stem between converging parallel spokes. I simply chose that method because I thought it could be described and illustrated the most clearly.

If you want to build wheels with many different crossing patterns and be able to start the same way each time, I think Gerd Schraner’s methods outlined in his book “The Art of Wheelbuilding,” are great. –Lennard

Feedback on wheelbuilding and steering geometry
Dear Lennard;
First: Last fall I started to break spokes on by road bike wheels, both the front and rear wheel. Not being willing to part with my wheel set while the shop rebuilt them, I read the section on wheel building in your book, went to my local bike shop and ordered spokes and a truing stand. Following your instructions, I rebuilt my wheels. I have ridden the wheels all summer with out any problems- I have not even had to true them. Now, I should tell you this is not the first set of wheels I have built. I built two sets before, each time with someone who knew how to build wheels looking over my shoulder, telling me what I was doing wrong. These two events were at least five years apart, it taking that long to repress the unpleasantness of process. Following your directions was a joy, and I am thinking about rebuilding my Campy 8-speed shifters this winter.

Second: I read the article on steering geometry in VeloNews and the threads in this column on it with some interest. Several years ago, I helped develop the “RowBike”. Our initial idea was to make a foot steered bike – basically, we put a rowing machine on two wheels, welded some foot pegs onto the forks and tried to ride the thing. The device was unrideable- after a few weeks of trying, I could balance the thing for a hundred yards.

After experimenting, we had to reach the conclusion that your feet are just too stupid to steer into a fall. Next, we made a RowBike with hand steering. In order to determine the proper steering geometry, we made a front end with adjustable fork rake and trail. After much messing around, we found that an 80 degree head tube angle with lots-like 5 inches- of negative offset was the most stable. I don’t know about shimmy- I would not want to go much over twenty on a bike with a sliding seat and handle bars that move back and forth, but this bike was super stable- a recumbent position you could ride no handed at very low speeds. –George


VeloNews technical writer Lennard Zinn is a frame builder, a former U.S. national team rider and author of several books on bikes and bike maintenance including the pair of successful maintenance guides “ Zinn & the Art of Mountain Bike Maintenance” and “Zinn & the Art of Road Bike Maintenance.” Zinn’s VeloNews.com 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 each Tuesday here on VeloNews.com.