Slowtwitch Forums: Triathlon Forum: Tubular Question

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Slowtwitch Forums: Triathlon Forum:
Tubular Question

shulessjoe

Aug 25, 08 9:28

Post #1 of 17 (524 views)

Tubular Question	Can't Post

All, I recently purchased a set of new wheels (808) and put on Zipp Tangente tubulars. I noticed on the front wheel/tire it seemed to be out of balance and out of round. If you held the wheel up in front of you by holding
the skewer and would spin the wheel you could both feel and see that the setup wasn't "true". I took the tire off and reexamined the wheel and it looked to be true (brand new gear). I took the wheel and another new
Tangente to the LBS and had them glue on the new tire. Same exact results as before. They had a truing stand and we took a look at it there and you could see a good 1/4 inch out of true when measuring the outside
of the tire surface. The bike mechanic told me this was perfectly normal for these tubulars since they are hand made. I am struggling to accept this and was hoping to get some comments from the experts. It seems there
is so much research and testing done on many aspects of racing bikes, and it just doesn't jibe to have a tire out of round? Thanks,

paul@hellovelo

Aug 25, 08 9:33

Post #2 of 17 (514 views)

Re: Tubular Question [shulessjoe] [In reply to]	Can't Post

That's a tubular tire for you. Glue bumps, doubled up tufo tape and off centre tires all contribute to a poor ride.

Are you looking at "true" with the tire is pumped up to proper riding pressure or only with a low pressure. The imperfections often disappear or are significantly minimized once they are ready to ride.

p.
------------------------

Padyak Pinoy in 2009?

hellovelo.ca

JamieJ

Aug 25, 08 9:37

Post #3 of 17 (508 views)

Re: Tubular Question [shulessjoe] [In reply to]	Can't Post

I had the exact same problem and did the exact same experiments as you with new Hed Stingers a couple of years ago. I called up Hed and they said that the wheel was probably the culprit. I sent it back, they sent me a new one...problem solved.

2009 Races:
TTT, Muncie Endurathon, IMoo

Ti T'war

Aug 25, 08 9:48

Post #4 of 17 (497 views)

Re: Tubular Question [shulessjoe] [In reply to]	Can't Post

Is it a 'Bulge' in the tire, or is it not glued straight on the rim? If it is a bulge then I don't know what to tell you, but if it is just not straight on the rim, it is easy enough to fix. Was the rim true? that 404 should true up pretty well if not.

I'm assuming that you are talking about being off to one side and not out of 'round' which implies that the wheel is oval or has a 'bump' or 'flat spot'.

Oh and deep wheels often feel like they have a 'hop' in them because the long valve extenders throw the balance wayyyy off.
__________________________________________________
It's T'war like 'car'
http://www.tritwar.blogspot.com
This is your life, and it's ending one minute at a time. - Fight Club

Dapper Dan

Aug 25, 08 9:50

Post #5 of 17 (494 views)

Re: Tubular Question [shulessjoe] [In reply to]	Can't Post

1/4 inch seems excessive to me.

Normally I mount my tires with the glue already dry on both the rim and the tire. This way I can play around with the tire and get it as straight as I have patience for. It is pretty easy to move it around until you fill it totally hard and put weight on it. Once you ride it, it is on every bit as strong as any tire mounted wet. If you put them on "wet" it is easier to slide the tire around on the rim, so it will tend to go where it wants to and any lack of roundness in the tire will be difficult to correct. It is also a lot messier in my experience.

If it seems out of round, I would assume the side that bulges furthest from the axle didn't get stretched enough. Probably hard to fix without removing the tire and starting over. But...you shouldn't need any more glue, just peel the tire off and put it back.

shulessjoe

Aug 25, 08 10:05

Post #6 of 17 (470 views)

Re: Tubular Question [Ti T'war] [In reply to]	Can't Post

Both times the tires appear to be put on straight. Since it was my first time that is why I took it to the LBS to have them glue on the 2nd tire, just to make sure it wasn't something I was doing wrong. To me it appears to be a bulge and ironically both tires had the same bulge at the same place on the tire. (the valve stem area) But you can't see the bulge without a truing stand or without spinning the tire. To use your words it is like a "bump".

Thanks!

paul@hellovelo

Aug 25, 08 10:59

Post #7 of 17 (435 views)

Re: Tubular Question [shulessjoe] [In reply to]	Can't Post

I have the same "bulge" on a set of EC90 Aeros with Conti-sprinters and if it isn't pumped up to around 140 psi, I can feel the bump on the road. Sometimes these things work themselves out after the first few rides after the tire really seats and sticks to the tire.

p.
------------------------

Padyak Pinoy in 2009?

hellovelo.ca

psycholist

Aug 25, 08 11:21

Post #8 of 17 (415 views)

Re: Tubular Question [shulessjoe] [In reply to]	Can't Post

I made a similar post after I first glued up a set of Tangentes. Apparently, they're a bit notorious for being out-of-round. I was lucky that I had a different issue with them and they sent me some free ones. Out of six, I wasn't able to find but one that was truly round. The rest all were inconsistent.

If you can buy from an LBS, do so. Mount the tire dry (no glue) and inflate it to see if it's round. If it's not, take it back to the LBS and exchange it. Or take your wheel to the LBS and do it there so you don't leave the store with a tire that isn't round.

OR ... go back to clinchers. They're generally faster anyway (if you use the right tube and tire).

.
Bob C.

Wreaking vengence on the young.

gibson00

Aug 25, 08 12:01

Post #9 of 17 (392 views)

Re: Tubular Question [psycholist] [In reply to]	Can't Post

This is a common problem with tubies (bulge at the valve after mounting). Thats not to say they are all like that, just that it is something you see fairly often at the valve area when they are mounted, due to the way the base tape on the tubular fits around (or rides up) the valve.

Some tires are better than others in this regard.
For example, the newer Conti GP4000 tubulars:
http://probikekit.com/display.php?code=Y1110

the base tape is perfectly flat around the valve, and thus you won't get the bulge after mounting.

Sure, you can also get bumps/bulges/side play from glue/tape if you -really- screw it up, or cheaper tubies can just be constructed terribly.......but I'm pretty confident that the problem you are having is what I described above.

Cheers.

(This post was edited by gibson00 on Aug 25, 08 12:04)

Deus ex Machina

Aug 25, 08 12:19

Post #10 of 17 (376 views)

Re: Tubular Question [shulessjoe] [In reply to]	Can't Post

I would recommend checking the tubulars for defects before using glue to mount them. As mentioned, the tubulars are handmade are subject to some mis-alignment/imperfections. Most retailers should let you exchange the tires as long as they are unglued. If the retailer does not, then I strongly suggest using one that will allow exchanges on the next purchase.

As a note, I found that some discount retailers seem to carry more factory "2nds" than what appear to be at random. I was using one discount store that kept on shipping me tires with bulges when mounted, but then when I purchased the same tires from what was a "premier" store, none of the tires mounted less than perfect.

FatandSlow

Aug 25, 08 13:05

Post #11 of 17 (347 views)

Re: Tubular Question [shulessjoe] [In reply to]	Can't Post

The only time I've had a similar problem is when the valve hole wasn't sufficiently large enough for the valve to seat properly. But that was a "training" tire. I have a tangente on my rear 808 and have no problems. The wobble sounds like the tire isn't properly centered.

xntrickly

Aug 25, 08 13:34

Post #12 of 17 (323 views)

Re: Tubular Question [gibson00] [In reply to]	Can't Post

With all due respect... I listened intently to the Conti information about the GP4000S and bought a pair. I stretched them on the rims nicely (very tough to get on the rims) and glued them on as I have done for the past 20 or so years. Sad to report that they had terrible hops at the valve despite the claims to the contrary. Back to Vittoria CXs for me.

best regards.

gibson00

Aug 25, 08 15:41

Post #13 of 17 (289 views)

Re: Tubular Question [xntrickly] [In reply to]	Can't Post

In Reply To

Interesting. Sorry to hear about your experiences. I'm not a dealer....I buy my contis from probikekit.com. I've had 6 of the GP4000's and they all mounted great, straight with no hops, which is the main reason I liked them so much!

echappe

Aug 25, 08 16:21

Post #14 of 17 (276 views)

Re: Tubular Question [shulessjoe] [In reply to]	Can't Post

All-
Zipp Tangents are Vittoria CXs. Same tire, different pattern on the rubber. Marketing at its best.

The hop at the valve stem can be caused by construction of the tire, as some others have posted. It can also be in the mounting technique. if the tire is not pushed very well into the valve hole, it can be an issue.

That said, having glued over 100 tires this season, there are still apparent "hops" in the when you hold the wheel and spin it in your hand, especially if you have not yet ridden the wheel. On nice tires like the Tangents (or challenge cronos, schwalbe stelvios or vittoria CXs) you should not feel the hop when you ride. On lesser quality tires you might, especially if the mounting has been sub-par.

The vibration you feel in a larger wheel like the 808s is the valve extender, mold release within the carbon fairing and carbon epoxy build up. Because Zipp goes to great lengths to ensure a light wheel, slight imperfections can seem bad. The best test is to ride them. Then, if you have a problem it is actually a problem with the equipment.

And with regard to tubulars vs clinchers, at this point in time, better tubulars offer a better ride quality, and good tires offer less rolling resistance. Clinchers such as MichPro3s show a very low rolling resistance, but their real world riding characteristics are not as nice as a tubular. That said, in a triathlon when you have to change a flat yourself, its a bit harder to deal with than a clincher.

------------------------
http://www.racewheelrental.com
Echappe Equipment, An Elite Advantage
Official Race Wheel Sponsor of 2008 Nautica NYC Triathlon
Be an educated consumer- test equipment before you buy it.

xntrickly

Aug 25, 08 19:33

Post #15 of 17 (234 views)

Re: Tubular Question [gibson00] [In reply to]	Can't Post

In Reply To

Excellent news because I really wanted to use these as the chili compound promises 25% less resistance so I may have to try these again albeit from a different source (probikekit.com). Cheers.

psycholist

Aug 25, 08 21:05

Post #16 of 17 (205 views)

Re: Tubular Question [echappe] [In reply to]	Can't Post

On nice tires like the Tangents (or challenge cronos, schwalbe stelvios or vittoria CXs) you should not feel the hop when you ride.

This is consistent with my experience. I got fed up with trying to get a perfect glue-up with my Tangentes and ended up racing with a rear wheel (Sub-9) that had a fairly significant hop. On the road, I never felt it when running 120 psi or thereabouts.

.
Bob C.

Wreaking vengence on the young.

kristiancyclist

Aug 26, 08 6:49

Post #17 of 17 (151 views)

Re: Tubular Question [shulessjoe] [In reply to]	Can't Post

A good tire will mount straight. My Veloflex Crits are dead-on straight. They have a little bit of a hop on the valve stem but that seems to be almost inevitable on tubulars. I don't feel it and the ride is superb! My Vittoria CXes on my TT bike mounted dead-on straight relative to the the trueness of the HED3 wheels but lumpy. Probably time to clean off the gluing surface of the wheels.

I'm still kind of new to tubulars this year and my mounting is getting better as I practice more. Just takes time I guess.

I find that inflating the tire to some obscenely high pressure right after mounting will straighten it out some. The tire seems to unfurl. I thought about riding it a bit too (like up and down the driveway) to let the tire squirm and settle but I'm not sure if that that will have any effect.

-- Boris