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Technical Q&A with Lennard Zinn: Long-valve tubies; rainy-day rubber; that rare red glue; and still more on cog-cleaning

Need a long-valve tubie? Try VittoriaDear Lennard,I have been looking around and have been unable to find a long-stem tubular tire. Almost all the tire websites don't even mention the stem length. I thought for sure with the popularity of deep carbon rims there would be at least one company that offered a model with a long valve stem. Thanks for any help.Brian Dear Brian,My tire-aficionado friend Tom Petrie assures me that at least Vittoria offers tubular tires with 51mm long valves with a removable valve core as well as 42mm-length valves without a removable valve core. Vittoria also offers

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By Lennard Zinn

And away goes trouble, down the drain

And away goes trouble, down the drain

Photo: Lennard Zinn

Need a long-valve tubie? Try Vittoria
Dear Lennard,
I have been looking around and have been unable to find a long-stem tubular tire. Almost all the tire websites don’t even mention the stem length. I thought for sure with the popularity of deep carbon rims there would be at least one company that offered a model with a long valve stem. Thanks for any help.
Brian

Dear Brian,
My tire-aficionado friend Tom Petrie assures me that at least Vittoria offers tubular tires with 51mm long valves with a removable valve core as well as 42mm-length valves without a removable valve core. Vittoria also offers really nice valve extenders that work on any tire with a removable valve core. You remove the valve core, thread in the extender, and then thread in the valve core. Effectively, it’s a long valve stem (i.e., it doesn’t leak and you don’t have all the hassles with trying to use Teflon tape to prevent leaks).
Lennard

Tread compound for rainy rides
Dear Lennard,
I have an ongoing debate with a riding friend over winter tires. He claims that the “sticky” compounds make a big difference in riding in the rain. I contend that the surface area of a 700 x 23 that actually contacts the road is so small that it doesn’t really matter and thus ride the same tires all year round. If it does make a difference I’ll gladly change, as anything that helps is welcome in rainy Portland, Oregon. P.S.: Neither one us has come down more than once or twice a winter.
Lunch Rider

Answer from Vittoria:
Generally speaking, the tread compound can make a huge difference on tire performance, even if the contact patch is small (in fact, the quality of this contact becomes crucial!). Additionally, if we talk about wet surfaces, the tread pattern can also be important. But one thing at a time . . . .

Compound: A “soft” compound isn’t necessarily good on a wet surface (or in general). A compound is like a cake: You put together all the ingredients, you bake it, and then you have different parameters to evaluate if it’s good or not. Saying “a soft compound is good on wet” is like saying “a light-brown cake is going to taste good.” It could, but if you put salt in instead of sugar, or if the eggs weren’t fresh, your good-looking cake will probably surprise you.

Assuming that the best reinforcing fillers (silica – SiO2 – is recommended for wet conditions) and the right blend of polymers were used, the wet-specific compound will be softer (its Shore A hardness measurement will be lower) than a standard compound. An important feature of this special “wet-grip” compound is its microscopic stickiness, which allows the tire to have a firm grip on the ground… once it touches it!

In fact, we should remember that water forms a thin film between the tire and asphalt, acting like a lubricant, and that the effective contact patch of our tires is reduced on a wet surface. There is grip only where asphalt and tread come in contact, with no water between them. How can we maximize the effective contact patch? With the right tread design! Tread design: On a dry road the tread pattern makes no big difference for road-racing tires (the tread compound does most of the job). But years of experience in the worst conditions (like Paris-Roubaix) taught us that a diamond-pattern or a fish-bone design (or both, together, like in our Corsa CX and KX treads) can give that extra grip needed on slippery surfaces. The reason is simple: while the total contact patch is only influenced by tire section, inflation pressure and rider weight, the effective contact patch is also influenced by the thickness of the water film and by the “surface geometry” of the tread. A more aggressive tread makes up for a more wet-condition-effective surface geometry, increasing the effective contact patch. To conclude this short overview, some tips on choosing the best tire for the worst conditions:

Get a 700x23c tire section or more, and slightly reduced inflation pressure (to increase the total contact patch).

Look for a wet-condition-specific compound (to increase the quality of the grip, once tire and road are in contact)

Find an aggressive tread (to increase the effective contact patch)

Alberto De Gioannini
Product manager, Vittoria S.p.A.

And from Tom Petrie, tire aficionado:

I believe compound does make a difference (I had some Barum Paris-Brest tubulars that wore like iron, but would slide around if it even looked like it was going to rain). Most important is the contact patch. Keeping the tires a little softer than usual will certainly make any tire hook up better in the wet. The downside is increased rolling resistance throughout the ride. Eddie B’s advice back in the day was to keep your tires pumped as hard as usual when it rains, but back off in the turns. The idea was that you’d have low rolling resistance during the major part of your ride (when you’re going straight) and that you’d only have to sacrifice a position or so in the turns. Of course, you do have to remember to back off in the turns.

This also gives me the opportunity to spout off about contact patch. People want to look at the number written on the sidewall of a tire and pump it to that number. You’ll have 110-pound girls and 240-pound guys riding the same tire pressure. Wrong. You should pump your tires so the contact patch is about 1cm wide by 5cm long. You can easily check this by inking a section of tire, putting it on a piece of paper, and sitting on the bike.

For the benefit of product liability attorneys, all of the foregoing is urban legend. No responsible cyclist should ride his bike without first getting a check-up from his doctor and having his bike serviced by a professional bicycle mechanic.

Tom Petrie
Velimpex Marketing, Inc.

More on Clement red glue:

A reader who saw the recent question about Clement red glue has some for sale on eBay. And Peter Chisholm at Vecchio’s bike shop in Boulder told me that Euro-Asia Imports (dealer sales only) still has some left (at a very high price). He had just special-ordered some for Andy Hampsten.
Lennard

More on cog-cleaning:

My posting on the cleaning cogs and mentioning the use of diesel fuel by European professional team mechanics raised the ire of many. Here are a few of those responses:

1. Dear Lennard,
I’ve been following the forum on cleaning your cogs over the last few technical Q&A’s. There has been some talk about using diesel fuel as a means of “easily” cleaning the cogs while on the bike. I’d just like to point out that there are potential environmental issues involved with this. Could you please remind your readers to properly dispose of the “spent” fuel (and any other solvent for that matter)? That stuff just goes down the drain, and a lot of it makes it into the rivers and oceans. When you look at the statistics, 383 million gallons of oil classified as “down the drain” make it into the world’s oceans every year. The next largest contributor is what is considered “routine maintenance” at 137 million gallons. Granted, cyclists, and the amount of solvent they use, are a probably very small contributor but it’s just something to think about regardless.
Todd

2. Dear Lennard,
I have just finished reading the responses to your recent column on degreasing. I am surprised at the use of diesel fuel as a cleaner. I have never tried this as a solvent, however, I am sure it works quite well given that it is simply one petroleum distillate. Again, I do not know exactly how this would be applied, but I would urge you to caution your readers as to the potential environmental damage that may occur from careless use of petroleum-based materials as solvents. It is certainly not the best idea to allow fuels to be released onto or into the ground. The idea that “just a little” won’t hurt anything is simply not true. Petroleum spills are a costly environmental hazard, and in many areas even so much as a gallon of diesel fuel (if I am not mistaken) spilled on the ground is enough to trigger an environmental response and clean up team. This material should be collected and disposed of properly, and “properly” does not include the household sink or nearest storm drain!
Trevor

3. Dear Lennard,
So maybe I’m overreacting but using diesel fuel sounds like a terrible idea. It sounds like a terrible waste of a limited resource. What do you do with the dirty diesel? Someone in Italy suggested washing it off with water – the only problem is that homeowners dump more oil down the drain every day than the Exxon Valdez spilled into Prince William Sound. Washing the diesel off with water only makes a bad idea worse. I know not everyone is an environmentalist but we are all cyclists and the dirtier we make the world the less fun cycling will be. How come no one has suggested bio-degreaser or something citrus-based? They work great! I spent 12 years working in bike shops and never had a problem using a citrus degreaser except when trying to remove wax-based-lube buildup – then nothing, not even hot solvent, helped. Just a thought or two.
Dieter

To all,
I certainly recommend against the use of diesel fuel as a solvent and have always said so in my books, recommending instead the use of biodegradable solvents. That said, once they are laden with the old grease from your bike, biodegradable solvents are a toxic disposal mess as well.

And come to think about it, I guess I can no longer say that pro team mechanics are using diesel fuel. I certainly cannot make a blanket statement about the subject. Many pro team mechanics still use the same solvent cylinders with a long, thin hose and a thin wand with which they go around squirting cogsets prior to scrubbing them, eventually following up with dish soap and a power washer. Those cylinders used to be filled with diesel fuel, and you could often smell it, but it is quite possible that they are often now filled with bio-degreasers, as many of the teams are sponsored by lube and tool companies who sell such solvents.

As for where it goes, all of that gunk, whether it is a slurry of bike grease, road grime and diesel fuel or biodegradable solvent, goes right into the parking lot and ultimately into storm drains and out into the local river. For instance, this power-washed rinse of Roberto Heras’s bike the day before the Tour’s start ended up in the Meuse River through Liege, Belgium.
Lennard

Still more on cleaning cogs:

4. Dear Lennard,
I know you have already received a number of letters on this topic, but I wouldn’t feel satisfied if I didn’t send one in myself. As a new father of twins, I am amazed at all the baby gear available and waiting to be adopted by fellow cyclists. One such gadget is a plastic baby bib that has a reservoir at the bottom to collect mistargeted food items. For cyclists wanting to spray the cog clean or spray solvent directly onto the cog, this bib makes for an easy cleanup. Fasten the neck fitting between the largest cog and the spokes, and spray away!
Otis

5. Dear Lennard,
I seldom have to clean my cogs. I lube my chain with paraffin (melt the paraffin and pour it over the chain in an old pie tin, let it cool, then break away the paraffin). It’s a pain to break the paraffin away from the chain, and from between every link, but I make it easier by having two chains and rotating them. So if I swap (i.e., lube) the chain every week I only have to make “chain pie” every two weeks. Using a Wippermann chain with a ConneX link makes it easy to remove and replace the chain. I try to swap the chain every 200 miles. I think it lubes my chain very effectively, and my drive train stays very clean, with no crud-attracting liquid lube on it. It seems to work for me – do you agree that paraffin is an effective lubricant? Personally I think the trouble of messing around with the paraffin is less hassle than having to clean a cruddy drive train all the time.
Rupert

6. Dear Lennard,
If you have a power washer, apply or spray some citrus degreaser on the cogs, put the bike in a trainer with the rear wheel not engaged on the roller, aim the power washer straight down in a vertical fashion (being careful not to go laterally into the axle) and in less than one minute you have a cogset that is clean as a whistle. When I first did this I was amazed – an old cog looked brand new. I have done this 20 times or so, and as long as you are careful where you aim it works wonders. And if you hit the chain on the cogs you also get a sparkling, shining chain. The action of the jet of water on the cogs spins the wheel and gets the whole drivetrain crystal clear.
Glenn

7. Dear Lennard,
I had the same problem cleaning cogs as everyone else until this year when our team picked up a new sponsor that provides a process called TME, Thermo Molecular Enhancement that is supposed to make metals last longer. I had them process my drivetrain at the start of the season this spring (XT cogs and crank, SRAM chain) and have had virtually no wear and have the added bonus that my cassette still looks shiny new. I only use water with dish soap to clean my bike. This process is probably available in most big cities, but here is a link to our sponsor here in Michigan, Future Technologies Inc.
Steve


Technical writer Lennard Zinn is a frame builder (www.zinncycles.com), 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.