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Technical Q&A with Lennard Zinn: Clement glue, seat posts for big guys, squeak theory and more on cog cleaning

What happened to Clement red glue?Dear Lennard,I have been riding tubulars my whole life, and I have always liked the Clement red glue. Now I cannot find it anymore. Do you know of a source? Also, I have been using the Tufo tubulars with good luck. I just don’t understand how they measure the number of threads per inch in the casing. They claim 420, yet Vittoria says their 290tpi is the highest density on the market. Any observations?Mark Dear Mark,I, too, loved that glue and have missed it. When Clement went bankrupt and was acquired by Pirelli, I think that the Clement red glue might have

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By Lennard Zinn

What happened to Clement red glue?
Dear Lennard,
I have been riding tubulars my whole life, and I have always liked the Clement red glue. Now I cannot find it anymore. Do you know of a source?

Also, I have been using the Tufo tubulars with good luck. I just don’t understand how they measure the number of threads per inch in the casing. They claim 420, yet Vittoria says their 290tpi is the highest density on the market. Any observations?

Dear Mark,
I, too, loved that glue and have missed it. When Clement went bankrupt and was acquired by Pirelli, I think that the Clement red glue might have continued to be available for awhile, but that probably was just old stock and dwindled.

A couple of times, the brand has reappeared in tires, but I have never seen anyone reintroduce the glue. Last year, Vittoria licensed the Clement name from Pirelli, for instance, and produced some of the classic tire models again. That contract is not continuing, so there are no Clement tires or glues on the market now. That said, I do like Vittoria red glue.

As for your second question, Vladimir Juhas of Tufo ( says: “The tpi count depends where it is measured – ours are 420tpi under the tread, 210 sidewall, (elite series).”

I would also like to weigh in here, because I find it at best confusing and at worst deceptive that tire manufacturers do not all measure the thread count of only a single ply. The 290tpi casing of Vittoria really is 290 threads per inch on a single ply. The same can be said for the 300tpi tires introduced this year by Challenge (which, speaking of Clement, are made on Clement’s old equipment in Thailand).

But Continental, for instance, has quoted some incredibly high tread counts for some of its clinchers that have thread counts around 100tpi on a single ply, and they were simply adding together the tpi of each layer of casing. Any tire has at least two plies, since the threads need to run at right angles to constrain the air. If you just add plies, then it would look like a stiff tire with lots of plies was better because of the high thread count, when we all know that a more supple tire is the one with thinner threads and fewer plies.

Skip the carbon post, big guy
Dear Lennard,
My MTB frame requires a 27.2 seat post. I was thinking about upgrading the seat post, but I became concerned after looking at a vendor website that mentioned a seat post meant for heavier riders, and specifically said 200lbs. I’m 6-foot 6, with a 36-inch inseam, and weigh 240lbs.

I was looking at both carbon and titanium seat posts. Due to my height, I require significant extension of the seat post. My current seat post is 330mm aluminum and the max extension mark is comfortably set a centimeter or two into the frame. Should I have any concerns? Are there any products I should stay away from due to my weight? Could you make any recommendations?

Dear Adam,
Yes, you should have concerns. I would shy away from carbon seatposts if I were you. You obviously seem to be into lightweight equipment, so I won’t tell you to just get a super thick post. I recommend that you look for aluminum posts with the thickened front and rear wall (sometimes called “butted”) for greater support.

An Avocet that chirps like a bird
Dear Lennard,
Some time ago a reader wrote about a creaking noise from the headset or stem when riding out of the saddle. To eliminate this, he tightened down on the headset more and reasoned that if he had to replace the bearings sooner, so be it. Well, I discovered something recently. My Avocet computer died, and not knowing when I would buy a replacement, I decided to remove the dead weight right away. On my next ride during the first climb out of the saddle, there were no creaking sounds. My theory is this: When the fork is subjected to more stress, the more the fork will flex & twist. When this happens, the nylon ties that secure the computer sensor & wiring to the fork blade start singing … much to our chagrin.

Here is some feedback on last week’s column about cleaning cogs.

I am amazed at the flood of responses I got about cleaning cogs. The majority suggested “flossing” between the cogs with a rag or a shoestring (both with and without solvent on the rag). I think you can all imagine that method and likely use it already (and for those with my maintenance books, it is illustrated in them), so I only included one of those letters. I guess I should have mentioned that method last week and saved a lot of you the trouble of writing me… I am posting a sampling here of other letters.

1. Dear Lennard,
I struggled with cleaning cogs, too, for a long time. There seemed to be no quick and safe way to get the drive train on my bike clean, and I tried many cleaners. Finally, I met another local (Charlotte, North Carolina) rider that owns a chemical manufacturing company. Their products are soaps and degreasers. Being an avid mountain bike racer, the owner has developed a soap that works very well on bikes but it’s not currently available on the market. I’ve got the process down to five minutes or less and everything comes out sparkling. No problems with it harming any other part of the bike.

Is there a way I could get him hooked up with you and/or VeloNews? I love his soaps, and I think the rest of the cycling world would too. He’s the Clif Bar of soaps.

Dear David,
Sure, send me the info.

2. Dear Lennard,
Regarding cleaning cassettes, the best and simplest thing I have come across is to use a brush and spray-on silicone waterproofing (e.g., Scotchgard or its cheapo equivalent). The spray is a great solvent and with some easy brushing, everything comes off quickly. The best thing about this is that future dirt doesn’t stick very well, so your cassette stays clean longer.

3. Dear Lennard,
Chris’ e-mail concerning cleaning cogs without removing them brought up a question I often encountered from customers. Most folks don’t want to go through the proper method, which would be removal and a bath in the solvent tank. On the other hand, what a race mechanic does with diesel fuel isn’t going to be the best choice for someone who has to pay for parts and labor.

So I say this: Find a shop rag and floss the cogs. By holding the rag at each corner (if it has corners) and inserting the edge of the rag (the finished edge of the rag, or a doubled-over rag for a thicker edge) into the spaces between cogs, you will be able to floss forward and rotate the cog backward for another dirty section, then next pass forward, etc. By holding the corners taut you can largely avoid the cogs snagging the rag on each pass. Spray the rag with a solvent if you want to, but solvents sometime smear more than they clean, especially on cogs that are not very scummy. A good deal of the dried stuff in there can be knocked off without solvent. Keep a clean edge of the rag in there or you’re just spreading the yuck.

If things are crusty after you do this, then pick out what remains with something suitable for the job. Compressed air cans like the ones you use to clean your computer keyboard will usually get the loosened bits out of there. Blow down from above and rotate the cranks backwards. The remaining dirt and grime will be on the contact surfaces of the cogs, where they meet the chain. Use a rag and your index finger to rub the stuff off each one.

Sound tedious? It’s not. Are the cogs cleaner than if they were removed and bathed? No. But they are as clean or cleaner than the other methods mentioned, without the infiltration of solvent into the bearing surfaces of the hubs, not to mention your spokes, hub, rim and frame. But the floor will be a mess.

The real issue then becomes: How clean is the chain? Chains are “cheap” relative to the replacement of major drivetrain parts. So if it is showing signs of wear, or you have kept track of your mileage and it is time, get a new one. Or take the lube manufacturers at their words and lube the chain, then pray to the god of self-cleaning. To mitigate future cog cleanings it is also a good idea to floss after you lube to remove the “wet” surfaces on the sides of each one of the cogs. Otherwise they hold on to whatever touches them, and the chain will have enough lube on it to moisten up the cogs where it contacts each one.

4. Dear Lennard,
Here in Brianza, Italy, everyone cleans cassettes with diesel (I use white gas). I have not seen problems if you wet everything down with water first, and are reasonably careful (though it may be considered improper maintenance by most manufacturers and, as such, void your hub warranty). I have seen many more problems by cyclists power-cleaning at the car wash.

Tying pieces of old inner tubes on the hub on each side of the cassette body helps to alleviate my contamination fears, and just brush on a layer of diesel, let it sit a minute, scrub real good, and rinse with a water bottle. The best bet is to remove the cassette, but we are a lazy breed. Overhaul your hubs once or twice a year, and use lots of good grease and high quality bearings.

5. Dear Lennard,
Another nice method to clean a cassette or a freewheel on the wheel involves a cheap 1-inch paintbrush, WD-40 and a shop rag. Use the paintbrush and the WD-40 to scrub the cassette, then pull the edge of the rag between the cogs so as the cassette will spin as you go back and forth. If the excess WD-40 makes a mess, use soap and water to clean it off.

WD-40 can be great solvent without hurting anything. I used it on the bench at my shop when I did not want to take something to the solvent tank.

And finally, White Lightning weighs in …

I recently read your Technical Q&A with Lennard Zinn about dirty cogs, and seeing as how one of White Lightning’s products is mentioned, Clean Streak, I thought some input direct from the horse’s mouth might be helpful. In the article, Chris has a question about cleaning his cogs. He’s currently using White Lightning CleanSafe (I think he means Clean Streak) degreaser to clean his chain, but he’s reluctant to use it on the cassette as he fears the degreaser would get into the freehub bearings. Chris is not the only person to express this concern, and I’m sure he won’t be the last person. I would like to reassure Chris that Clean Streak will cause no problems with the freehub assembly. Here’s why: The unique Clean Streak formula is not only designed to clean effectively, but evaporate very quickly. This rapid evaporation will ensure that the degreaser will not have time to penetrate into the hub assembly and cause a breakdown of the hub’s lubrication. Also, Chris mentioned that when he cleans his chain, he uses a rag to prevent the Clean Streak from getting on the frame. Again, Clean Streak will not harm the frame because of its quick-drying, no-residue design. I hope this helps to address Chris’ concerns, as well as anyone else who has similar worries. I would also like to touch on the comment made by Paul Morningstar. His recommendation that riders use a chain lube which does not attract or hold dirt as a means of keeping the cassette clean certainly hits close to home for me. Not only would I agree with this recommendation, I have a recent and personal story that relates to this issue. A few weeks ago, I was testing a number of different “wet-style” lubes. Here’s what I discovered: As my chain got progressively dirtier, the dirt worked its way into my chain’s sideplates, inner plates and rollers, causing a gritty, rough sounding noise. The over-spray from the lubes that got on and in my cassette became a magnet for grit and grime. Eventually, I decided to regroup with White Lightning Original. I cleaned my chain and cassette, applied White Lightning, went for a ride, came back and reapplied a top coat.

On my next ride, I noticed the aforementioned noise was completely gone. The top coat had fully dried and the wax component encapsulated the dirt that was hiding in my chain. As I began to ride, the product’s self-cleaning/shedding technology quickly expelled most of the dirt contaminants. After a few more rides I also noticed that grime was not building up in my cassette. All of this was no great surprise for me, but it was nonetheless reassuring to see such dramatic results. Although this anecdote is obviously self-serving, I would encourage your readers to experiment with dry wax-based lubes, like White Lightning Original, especially if they are having troubles with conventional “wet-style” lubricants.

Josh Marceau
Sales and marketing managerWhite Lightning Co.

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 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.