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Tech letters for June 19, 2003 - Answers #1

Edited by John Stevenson

Confounded by carbon fiber? Need to sound off about superlight stuff? Tech letters is the forum for your gear-related questions and opinions.

Send your emails to Cyclingnews' tech desk

Answers and reponses to questions raised last week.

This week's Questions   Answers #2

Gluing Tires
Auto degreasers
Chain slipping
Hard to find bits

Gluing Tires #1

It was my assumption in writing this article that the user would be racing, not touring or recreational riding. There are substantial forces on tubulars during competitive use, and tubulars should be bonded to the rim as strongly as possible. I did ride and race on tubulars, Clement Setas, when I could afford them, glued to Fiamme Red Label rims. I have glued tires for professional riders. I have seen riders roll tubulars in a race, and it is not a pretty sight.

Calvin Jones
Park Tool
Tuesday, June 17, 2003

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Gluing Tires #2

I do not pretend to speak for Mr. Jones. However, he and I have worked together for nearly 12 years on a variety of projects including as National Team Mechanics at the World Championships and teaching race mechanics at the US Olympic Training Center. I do know that Mr. Jones' primary axiom is: "The safety of the rider is paramount." The methodology that he recommends in his CyclingNews article is founded upon this axiom.

I feel compelled to respond to Mr. Cushing-murray. The statements put forth without support need discussion.

The 'forces' holding the tubular tire to the rim are the tire stretch, the mating surface shapes, the air pressure, the base tape to casing adhesive and the tubular adhesive bonding the base tape to the rim. If the tire and rim have concentric shapes in cross section with good contact, if the tire is inflated and if the tire has a suitable diameter relative to the rim, these forces account for nearly 30% of the total force holding the tire to the rim. The proper rim adhesive with proper installation accounts for the remaining 70% of the total possible. (The base tape adhesive fails when the rim adhesive is improper or when degreaser-like material comes in contact with this adhesive joint.) Of course, if the improper adhesive is used or if the installation of the adhesive is improper, the total force holding the tire to the rim is substantially less. No adhesive would mean that the binding 'force' is only 30% or less of what is possible. Mr. Jones recommends the method that provides the greatest total binding force. The purpose is to keep the tire on the rim under all conditions, not to make it easy to come off when there is a flat.

Let's examine each of the points espoused by Mr. Cushing-murray. I speak only for myself. I do not work for nor represent Park Tool. Experienced mechanics should always couple any recommendations put forth with their own observations.

Mr. Cushing-murray recommends 3M Fast Tack Trim Adhesive available at any US auto parts store and likely available elsewhere. This adhesive is designed to hold body side molding onto the painted surface of a car, e.g. rubber bonding to paint. This is a substantially different bonding objective than holding base tape (latex or not latex coated) to aluminum (anodized or not), resin-coated carbon fiber or wood. I have shown through extensive experimentation that Fast Tack is inferior to tubular glues, notably Continental and well-mixed Mastik'One from Vittoria. Fast Tack does not hold up to high temperature either, which may arise from braking on high-speed descents. It is inferior and is not recommended. Further, Mr. Cushing-murray is wrong regarding the implied curing time. Fast Tack is slower than most tubular glues to come to strength. Therefore, his implied recommendation that the tire can be ridden in an hour because of sound gluing methodology is incorrect.

CyclingNews editors make a good point regarding the solvent action of Fast Tack. There are two adhesive joints in tubular tires. The one is the rim to base tape joint. The other is the base tape to casing joint. The latter is generally latex (hydrocarbon-soluble polymer adhesive) based. Consequently, any material that uses a hydrocarbon like solvent will dissolve the base tape to casing adhesive joint. The base tape may stick to the rim but the tire will still roll. Migration of the adhesive plus solvent through the base tape means the solvent is coming in contact with the latex. The Fast Tack solvent (Part No. 08031) is hexane. This is a gasoline-like hydrocarbon. It is also the solvent in which most latex's are produced by the chemical industry.

We have also tested all of the recommended gluing procedures including the manufacturers' recommendations, the editor of Bicycling recommendations, the technical editor of VeloNews recommendations etc. All are inferior to Mr. Jones' recommendations, in some cases, substantially.

I have not tried Mr. Cushing-murray's recommendation of roughing up the glue surface with an automated wire brush. However, if the glue is relatively fresh, this will gum your wire brush. Remember that the tubular adhesives are contact cements. They will redissolve in their own solvents. So putting another layer of glue on the rim and allowing dissolution time will allow you to spread the old glue more evenly. Dissolution time is far shorter than curing time (evaporation of the solvent).

There are a variety of ways to make tubulars come off the rim more easily to change a flat. A gap in the Tufo tape, gaps in gluing such as 'Triathlete patterns' or inferior gluing methods will all make the tire come off more easily. Of course, what comes off more easily standing still comes off more easily during sudden loss and catch of traction while riding. 'The safety of the rider is paramount.' We should never fall into the trap that an unrolled tubular is installed to the highest level of adhesive joint integrity.

Regarding the time commitment, I don't find this onerous in the least. Tubulars can be prepped long in advance. Once cured for 24 hours, they can be properly folded and stored in a freezer lock bag keeping the base tape surface clean. Yes, the original rim prep takes two days but once properly prepped and used, the flat is removed, new glued applied and the prepped tire installed, yes, faster than replacing a clincher.

Mr. Jones references my website that has the data supporting his recommended practice and the claims that I make in this response. We, who ride tubulars, all have our methods, experiences and tales of failure. But if the gods ever came to Earth, they would ride tubulars.

Colin S. Howat
Director, Kurata Thermodynamics Laboratory
University of Kansas USA
Thursday, June 12, 2003

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Gluing Tires #3

As a mechanic, generally I agree with what Jim wrote about the reliability of tubulars and the use of Tufo's tubular tape. However, Jim's advice on using Fastack should be taken with a grain of salt. While Fastack will hold the tire on very well, it also has the propensity to soften the base tape of high-end tubulars, thus ruining the tire if you need to re-apply it or put it onto a different wheel. The park article gives the best method for high-end race tires. But if you use tubies for training than Fastack away!

Greg Abbott
Connecticut, USA
June 12, 2003
Thursday, June 12, 2003

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Gluing Tires #4

I agree that gluing does not have to be the mysterious and arduous process that many make it out to be. My only rebuttal to Mr. Cushing-Murray's letter, however, would be to his recommendation of Fastack. I have found Fastack to dry far too quickly for my tastes. On one attempt I applied a second coat of glue to the tyre and then one to the rim. By the time I was done applying the glue to the rim the tyre was completely dry and had lost all of its "stick" in a matter of ~3minutes. I'm a big guy and use a lot of glue so it was not a matter of too-thin a coat. I prefer glues such as Panacement that are of a perfect consistency to work with, in my opinion, and take slightly longer than Fastack to become tacky allowing the time to get the tyre mounted while the glue is still setting, a very important detail.

I would not think that Fastack would be appropriate for a novice tubular user as that person may mount a tyre and not have it properly adhere to the rim if the glue dried too quickly before the tyre was mounted.

Rob Coapman
USA
Saturday, June 14, 2003

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Gluing Tires #5

I too am a tub fan, especially now that the tyre sealant is available, tubs that repair themselves, wonderful. An added bonus is that for an older training bike, really good second hand wheels can be obtained really cheap. I came across a shop selling new tub rims for £1 each a couple of years ago. Decent clinchers wear out so quick they can prove very expensive and the tub rims don't wear out nearly as quickly from braking. On top of all this, the ride is more comfortable. I've ridden tubs without glue with no problem, as long as I remember to go a little easy on the corners.

Dave Moss
UK
Sunday, June 15, 2003

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Gluing Tires #6

I agree for the most part Jim. Although Fastack can affect some base tapes, as mentioned (mainly Continental), Vittoria's Mastik, and Panaracer glues both are fine. However, after 15 years of gluing tubulars, I have stopped. Why? Because the Tufo gluing tape works better than glue, is easier to change a flat (achieving a permanent repair), and takes ten minutes to put a pair of tires on when you get good. Take a well glued wheel at 100psi, and try to unbond the tire by pushing up on the side wall. Now try the same with a tire with Tufo's gluing tape, it simply has a much larger bonding area on the rim than the glue, and is also more resistant than the glue to unbonding.

I think it is pretty funny when I hear of the 4 day rituals that pro bike mechanics go through to get a tire "properly" glued, when all it takes is 5-10 minutes and this tape. The 10 or so wheels, with different tire combinations, that I have built and used this tape, have been nothing short of lovely. Best part is, that you can true the tire on the rim, in a stand, at about 40 psi, because it has taken almost full shape, but hasn't "stuck" and won't until close to full inflation. The result with a Tufo tire and gluing tape, usually looks as round and straight as a clincher.

Mike Knudsen
Monday, June 16, 2003

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Gluing Tires #7

I agree that some of the latest instructions for gluing tubs seem like they were written by liability laywers, however Fastack is well known to dissolve the glue holding the tires base tape to the casing, especially with Continental tires. Better use Continental or Vittoria amber glue (not the nasty red stuff). The most important thing about gluing tires is making sure the rim is devoid of grease or oil (common elements in a workshop). After that Jim's process of glue on rim, glue on tire and then a thin layer of glue on rim again for final mounting should be fine.

Howard Chang
Tuesday, June 17, 2003

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Auto degreasers #1

The bike shops sell a lot of things at highly inflated prices that we are meant to believe are better for our bikes. And that's great if it makes you feel better. But not so great if you don't want to throw away money. I have found that sewing machine oil (that I initially knicked from my wife), purchased from the supermarket, works just fine. I apply it in the evening then let the bike sit over night. I rub the excess off with a cloth before my morning ride. After the ride I get the cloth out again and then maybe again after the afternoon ride. I stay away from degreasers and use a dry cloth instead. Every couple of weeks I'll pull a small strip of cloth through each link to get ride of any build up of grime. I also pull the rear cassette apart and wipe it clean with a cloth. This system works very well. My bike is well lubed and stays nice and clean.

Hope this helps someone.

Ross Mackintosh
Rolleston, New Zealand
Tuesday, June 10, 2003

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Carbon wheels at the Giro #2

I'm pretty sure that the wheels that Garzelli and Pantani were riding were either ADAs or Lightweights. ADA's are the originals; they're German-made by Cees and Ada Beers. The Lightweight's are also made in Germany by Dierl and Obermayer, who I believe used to be former partners at ADA. Neither company sponsors anyone, that's why they're unmarked; the wheels are so amazing that pro's are willing to buy them with their own cash, about $3000 in fact! A lot of riders have a pair or have used them, the first being Bjarne Riis when he won the Tour in 1996. Since then I've seen them ridden by Max Sciandri, Jan Ullrich (including during the 2000 Olympics), Joseba Beloki, Richard Virenque, Laurent Jalabert (when he won the KOM in the Tour), Tyler Hamilton (he used Bjarne's old wheels in last year's Giro, including when he crashed descending), Mario Cipollini (including during last year's World's), and Lance Armstrong.

I've heard that Lance originally wanted a pair of ADA's, but since the company wouldn't give them to him for free he got a pair from Lightweight. These are the wheels he first used in 2001 in the uphill TT's in the Tour of Switzerland and the Tour de France. Last year he supposedly got into some trouble with his wheel sponsor, Bontrager, over using them.

The wheels are frighteningly light, starting at about 800 grams a pair! They're supposed to be incredibly strong, but as of yet I haven't met anyone willing to pay a bike's price for some wheels. For more info, check out:

http://www.ada.prorider.org/

http://www.lightweightwheels.com/

Jeremy Landau
Miami, Fl
Wednesday, June 11, 2003

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Carbon wheels at the Giro #3

This question has come up since 1996, when Bjarne Riis used the same wheels in his winning TdF campaign.

The wheels in question are made by either of two different companies but are quite similar. There is an ongoing dispute about who came up with the idea and who copied it, and you can read all about that online.

The wheels are produced by either ADA [Cees Beers]or Lightweight [Dierl and Obermayer] - and can be visually distinguished from the color of the aramid spokes. They are indeed light in weight, but be warned - they are very stiff.

They are very, very exotic - but not cheap. Even though I could afford them, I purchased a set of American Classic Carbon instead - at a third the price and similar weight, these wheels have performed perfectly on the rough roads of many Balkan mountains under my 175lbs for more than a year already.

For more information: Comments about the wheels, including the history, from different perspectives: www.slowtwitch.com

ADA wheels: www.ada.prorider.org

Lightweight: www.lightweightwheels.com

Hope this answers your question.

Michael Stechow
UN Mission in Kosovo
Wednesday, June 11, 2003

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Carbon wheels at the Giro #4

Rich, I can guarantee that these are not HED Alps wheels. I know, I work for them. We advocate an aluminum braking surface for almost all applications other than track. These wheels (that cost Garzelli the Giro), are all carbon, and most likely made by Lightweight (of Germany) or ADA of Holland. They are great for going up, but going down is another story. This is why when Garzelli and Pantani were caught in that awful weather in-between climbs near the end of the Giro, they had great trouble braking; just like Jan Ulrich two years ago, with the same wheels, when he hurdled into the creek. Meanwhile, Simoni had a plain pair of box section aluminum rims, that enabled him to get through just fine (along with some fine bike riding), and win the Giro. If you plan to go up AND down mountains, get wheels that can handle it!

Mike Knudsen
Monday, June 16, 2003

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Chain slipping #1

It could be a simpler fix than a new chain and cassette. I bought my new(ish) Cannondale F3000 about 6 months ago, and only one month in to riding it, I noticed the chain slipping heaps under pressure. Turns out that my large chainring was buggered. A new cannondale chainring that was too worn to hold a new chain! I put a raceface machined jobbie on there instead and voila - no chainslip. The teeth on the raceface ring are not so cut away as the ones on the cannondale ring. Shifting is a little more forceful between rings now, but the chain doesn't slip.

Moral of the story - check that it is not the chainrings first. Sometimes teeth can be so ramped that they might shift nice, but they won't hold a chain to save their life in real off road conditions.

Matthew Cobb.
Curtin University, Australia
Thursday, June 12, 2003

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Chain slipping #2

I own a Truth, as well, and had a similar problem. I agree with JS but I would first check the alignment of your derailleur hanger and make sure it is not bent. My hanger was bent ever so slightly, barely perceivable to the naked eye, and this fixed it immediately. Plus, if this fixes it you are not out any $$ for new drivetrain components.

Scott Whitaker
USA
Thursday, June 12, 2003

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Chain slipping #3

Most of the time this is because your cassette is worn. Chains stretch with use, and consequently wear into the cassette. When you replace your chain there is a good chance you will need to replace your cassette too. Usually I get one race season plus a month or two out of my MTB cassette and chain. I've tried replacing just the chain - which works as long as there is no load, but as soon as I would shift down for a climb the skipping would start. So now I just always replace them both and monitor the chain wear using a Park chain checker, I think I paid $25 for it. It lets me know how worn my chain is so I can expect when to replace the cassette and chain. Of course this is assuming your chainline, rear derailleur, etc is set up correctly. Also, I have never had worn jockey pulleys cause chain skip.

Joe Sweeney
Wednesday, June 11, 2003

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Chain slipping #4

I had the same problem. I'm running '03 XTR on my '03 Truth. Check your derailleurs carefully and make sure your cassette lockring is tightened to spec. If both of these check out you can try one or both of these fixes. Get the longer rear derailleur hanger from Speedgoat.com ($30). It has a 4mm longer hole-to-hole spacing. Or if you're running a 34 tooth rear cog switch to a 32 tooth - expensive I know, but it's worked wonders for me. I ended up doing both part switches to get mine to shift right.

Dominic
USA
Wednesday, June 11, 2003

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Hard to find bits #1

Try www.branfordbike.com for the Campagnolo part. They have an excellent shipping service. Have a look at www.campyonly.com as well. The forks you could try Cambria cycles in California. Not sure on the website but put Cambria cycles in a search engine. They have a big catalogue (or try Answer themselves).

Mark Rushton
UK
Wednesday, June 11, 2003

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Hard to find bits #2

eBay.com! of course!

David Malkin
Wednesday, June 11, 2003

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Answers #2