Tyre rolled off Tubular Rim through corner

[kosh]

Do the benefits of singles really justify all the extra work?

I was skeptical but now having tried them, that's a "hell yes"! The feel of tubular tyres on the road is remarkably different. Most noticeable for me was the sense of control when taking a criterium corner at speed. More than makes up for three days of tedious gluing.

[lynskey_rider]

(AT) foo, I have heard of and seen bostik being used before. How do you find it?

[foo on patrol]

I never rolled one using the Contact Cement but did roll one using Bostick but in fairness, it was in a sprint coming out of the home bend when I had a rider go down in front of me and I bunny hopped him but landed with the front crossed up.

If you take the time to have an even coverage of glue on the rim, then you're not going to have problems. It's when you shortcut or rush things where things go pair shaped and you get a whole lot of hurt happening. (I raced at the Aces level which was above A-grade so it wasn't slow poke racing.)

Foo

[redcorpsjames]

How does the tubular tape go in comparison to the cement. Have both on order for cheap, not sure what i am going to try?

[lynskey_rider]

James, personally I wouldn't bother with the tape. IMO, the tape is rather dangerous. The tub glue is by far superior. It may be a little messy and tedious for a first timer, but wrll worth the effort for the added safety as far as im concerned

[foo on patrol]

I used the tape only on my road wheels and never had a problem. Put them on with water on the tape and centred and then pumped up to 120psi.

Foo

[toolonglegs]

Good a thread as any to re-invigorate .
How often would you re-glue a tubular if isn't used often?. I have a 19mm tub on my front TT rim, wouldn't have ridden it for 6 months ( last TT was in September... next will be in April / May ... just 5k prologues
)... would you reglue it?.
It has been sitting in a dark dry basement.

[brentono]

I test the adhesion of my tubs by deflating them so they just have enough air to hold there shape and then try and peel the tyre off, if it peels away from the rim without your thumbs hurting or if you can see dry rim glue it again.

TLL
Think Be1 sounds right with this method. You need to check them, I would think.

Personally, sold a set of wheels that I re-glued recently. This method worked for me.
As you probably know, a good smear on the rim, and on the tire, and working the two surfaces
together, with a side-to-side move, works, then half inflate, to allow to set overnight, then you
can fully inflate, next day.

The mention of Shellac, earlier, is OK for Track, only. And is was interesting that L.R. had
experience with Carbon rims, as I don't. Shellac needs attention, and fairly constant, reworks.
But, great for a solid smooth ride (on the Track) It was back in the 'old days'

Just my 2c

[bomber]

If it ain't broke...

In all seriousness I don't think there is a need to unless you have a cause for concern i.e. the tyre has visibly aged etc

[toolonglegs]

Cheers, by the sound of it they should be fine then... they hardly get used for 10 months of the year and when they do they hardly get used anyway if you know what I mean. It is such a tiny little tyre that I am happy to leave it where it is as it still looks very well glued, not by me though, club president glued them up for me.
I am going through my first glue up experience at the moment... hopefully will be racing a crit Sunday on tubulars for the first time .

[foo on patrol]

TLL, they should be all good, as I had them on some of my wheels for two years at times. Including my finals wheels

Foo

[toolonglegs]

Glued up my new wheels... did it the way zipp youtube video showed... 1 layer on the tyre, 3 on the rim 24 hours apart... leaving the last for 4 or 5 minutes before putting the tyre on ( prestretched for a day or so ). Was so easy I thought I might have got it wrong ... didn't have to straighten the tyre out or anything.
1st impressions on tubulars... well hard to say as they are also a lot stiffer wheels than I have been on since selling my C50's. 58/88... rolls nice, certainly not as comfortable as the 25's I have been on. Give them a good test on Sunday on a nice little 70km crit with a tram line mid one of the corners... if it is dry that is. They are forecasting snow.

[brit_in_oz]

I never rolled one using the Contact Cement but did roll one using Bostick but in fairness, it was in a sprint coming out of the home bend when I had a rider go down in front of me and I bunny hopped him but landed with the front crossed up.

If you take the time to have an even coverage of glue on the rim, then you're not going to have problems. It's when you shortcut or rush things where things go pair shaped and you get a whole lot of hurt happening. (I raced at the Aces level which was above A-grade so it wasn't slow poke racing.)

Foo

Please, please, please don't use Bostik/Selleys or anyone other 'contact adhesive' to glue tubs thats sold for DIY. I work as a technical manager developing adhesives and have worked making/developing these products for over 10 years. Without going into a comprehensive chemistry lesson, the type of contact adhesive you get at Bunnings are chloroprene rubbers dissolved in solvent with a phenolic resin and magnesium oxide cross linker dissolved in toluene. As the solvent evaporates the rubber solidifies and goes through a crystallization process. Its in this time that it exhibits auto-adhesion (i.e. will bond to itself). After that time has passed its not really an adhesive any more, its a solidified rubber with stuff all adhesion. It won't form a reusable bond either, as the other components form a cross linking matrix preventing rebonding - effectively its one shot. Contact adhesives like this have a Bell shaped curve of adhesion, typically between 15-30 minutes after they become touch dry they show the greatest bond strength, before or after this time the bond is degraded, and can be a fraction of the maximum.

Compare this to (say) Vittoria cement, these are non cross linking pressure sensitive adhesives. These work by being permanently tacky, which is why when you pull one off a rim you can put a new tyre on it and the remaining adhesive will reform a bond. Use the right adhesive for the job and use the right amount and the chance of roll off is low/zero under standard conditions. It also explains why why tubs can fail on descents when carbon rims get hot, PSA adhesives (pressure sensitive adhesives) are thermally sensitive, that is they will get thinner as the temperature increases, and with decreasing viscosity the bond strength is reduced allowing the tyre to move when excessive force is applied. As it cools the viscosity increases once more and the bond strength increases again. A Bostik type contact adhesive is cross linked so doesn't thin down, but it will fail suddenly once a critical bond temperature is exceeded (depending on formula / chloroprene rubber grade used, this can be as low as 60-65 degrees or as high as 85 degrees or so.)

Well thats a brief explanation...the moral is to use the right adhesive for the job, don't be a tight arse and use the wrong product as it could cost you a nuked bike and body in the long run.

[foo on patrol]

Well Brit_In_Oz this is what I used in the 70s/80s along with many others and there was never a problem regluing back onto the rims. I tried the so called proper glue (Clement) and was no happy with it.

Had nothing to do with being a tight arse it is what worked and worked really well for me at the time. If they have changed the composition of the glue since then, well I don't know but I used it on Clement No1s and No3s which were hand made silk. Never got any deterioration of the silk and the were still good to go after restitching. Ran them at 150psi and got a full season to two seasons of racing out of them.

Foo

[Alex Simmons/RST]

I use Vittoria Mastik One on my carbon rims. Works very well (it's designed for the job). I apply with a cheap paint brush - makes getting nice even coats on rim and tub easier.

TLL - pump them up lightly and if you can't easily move the tyre away from the rim, you are good to go. Assuming tyre itself is in good condition. One thing to check is sometimes tyres can come away from their rim tape.

I glue mine such that removal can be a bit of a fight and usually means tyre replacement. It can be a bit of a tedious job, but I prefer the security. Some like to leave small patch unglued or lightly glued to enable them to remove more easily.

From a rolling resistance perspective, poor (over and under) glueing can increase rolling resistance significantly.

Use the right glue, and learn to glue properly. It's not hard to do, but plan ahead and take your time. Last minute glue jobs are not recommended.

[brit_in_oz]

Well Brit_In_Oz this is what I used in the 70s/80s along with many others and there was never a problem regluing back onto the rims. I tried the so called proper glue (Clement) and was no happy with it.

Had nothing to do with being a tight arse it is what worked and worked really well for me at the time. If they have changed the composition of the glue since then, well I don't know but I used it on Clement No1s and No3s which were hand made silk. Never got any deterioration of the silk and the were still good to go after restitching. Ran them at 150psi and got a full season to two seasons of racing out of them.

Foo

Hi,
1) If you were in the 80's you would be bonding to an aluminium rim, not carbon, hence have lower heat build up, which may explain why you have not experienced failures. I never mentioned deterioration, i am talking about bond strength and failure, nothing else. You *can* get a bond with them, obviously, but I would never, ever, use it.

2) Yes the composition has changed, in the 70/80's they would use a Dow chemicals grade such as Neoprene WRT as the base, or other quality rubber base. Now Chloroprenes come from China quite often. They have huge amounts of variability in viscosity and crystallisation rates. You can make a batch one day and then the next day it comes out totally differently in both viscosity and crystallisation rates. For DIY it doesnt matter too much but they are certainly inconsistent in performance.

You can do a simple test on timber, leave it 24 hours after glueing and see which adhesive will bond. Contact adhesives will not take, or barely hold together as they have lost the ability to adhere to themselves. A true tub glue bonds on pressure application. Same thing happens on your wheel as the bonding mechanism of a contact isn't designed for that application. If you want to play Russian roulette with your life go ahead, but I will stick with a product designed for the application.

[toolonglegs]

Grrrr... haven't had a puncture for months. 180km on a $100 tubular and it already has a slow leak . No time to glue up a new one before tomorrow I think.
I have a spare tubular, I will put a layer of glue on the base tape tonight, but if I give it a good 12 hours to dry, then put it onto the wheel with another thin layer on the rim left to dry till tacky. It will only be on the wheel a couple of hours before I race ( ambient temp will be around -2 to zero )... what do you think?.
I might try a bomb first as I don't these are repairable.
Much easier just to chuck my pneus back on the rear.

[toolonglegs]

Doesn't look like I need to worry anymore... might have been a valve extender working lose .
Anyway I have plenty of time to sort it out in the end as I think my race will be cancelled today due to white stuff .

[open roader]

Doesn't look like I need to worry anymore... might have been a valve extender working lose

I recently had this happen on one of my tubs to both my disdain and confusion - used the slightest hint of Loctite 222 on the base thread, no more slow leak

[toolonglegs]

I just cranked it up a bit tighter ... can't be bothered taking it off to loctite it or thread tape it. Should be fine.
Race was cancelled anyway due to snow and subzero temps. Should have warmed up a bit for next weekend... although there's hills next weekend .
BTW ... if the tyres are vulcanized, not stitched, can they be repaired ? ... maybe not by me but by a pro.

[open roader]

BTW ... if the tyres are vulcanized, not stitched, can they be repaired ? ... maybe not by me but by a pro.

I expect someone with the necessary skills could perform a repair dependant upon where in the carcas the damage is. However, being the stinking, capo wasteful consumer git that I am; I'd not want to ride on a repaired tubular for the sake of (in my case) an AU $67 replacement tyre......

[toolonglegs]

I am probably thinking more cyclocross tyres than road ... they don't wear much, I have had mine for the last two seasons and they still look like new.
I found this guy http://tubular-repairs.com/" onclick="window.open(this.href);return false; in the UK, I am sure we have the same here in France.

[toppity]

It's been years since I've glued on a single. After your success TLL I might give it another go.I have used Stan's no leaks in my tubulars with really good success. I've punctured during 2 races and the tubs have 'self healed' allowing me to finish. You loose some pressure but not enough to stop you.

There used to be a bloke in Melbourne who fixed tubulars, Jack McGowan (SP?), anyone ever associated with the CCCC would have known him. Sadly he has passed and I don't think anyone is around to do the job these days. With my last puncture I thought I would fix it myself, but I couldn't even get the backing tape off in one piece, so in the bin it went.

Good luck finding someone over there.

[ironhanglider]

This thread seems close to the mark for a discussion about Tubulars and how likely or not it is that they will roll in a corner.

Here is the opinion of Nick Legan who is well placed to comment on the Beloki incident.

Editor’s Note: VeloNews tech editor Nick Legan is a former ProTour mechanic who most recently wrenched for Team RadioShack at the 2010 Tour de France and elsewhere. His column appears here every Friday. You can submit questions to Nick at asknick@competitorgroup.com, and be sure to check out Nick’s previous columns.


Q. Nick,
As a bigger guy who really likes to push it on the downhills I’ve never been able to shake the image of Joseba Beloki’s rear tire unseating on the descent into Gap whenever I consider tubulars. How common an issue is that really? Since then, have you ever heard of pros using a heavier clincher setup on a hot day with a treacherous downhill just for the extra security of the rim staying on the bead? Or is Beloki’s crash written off as a freak occurrence with a hot day, hard descent, and potentially less than optimal tire install/line choice/braking point?
— Troy Browning
A. Troy,
You’ve asked a series of questions here and I’ll answer them all. But first I think it’s best to examine what happened that hot day in July of 2003. I watched Beloki’s crash live that day and since then I’ve seen the video more times than I care to remember (including a couple more times before replying to your question).

Beloki’s tire rolled as a result of his slide, it didn’t cause the slide. On a slick tar patch, his rear wheel lost traction under braking and when it almost instantaneously regained traction, Beloki high-sided. The tire rolled because he was sliding sideways. Even the best installed tubular will roll under extreme side loads.

Lance Armstrong had a similar crash at the 2010 Tour, though he was obviously able to continue. We at the hotel in St. Moritz heard that Armstrong had rolled a tire and went down. We collectively started to sweat. When we saw the wheel in person, we realized that our glue job was better than Hutchinson’s. The base tape was still attached to the rim bed. The tire casing had delaminated from its own base tape. It’s important to point out that this was NOT a failure on the part of Hutchinson or the mechanics that glued it on. Sometimes tires come off as part of a crash.

Sustained braking saturates a rim and tubular glue with heat. This is what leads to a tire rolling. In the old days, riders were taught to alternate between braking and coasting. This allowed the rim to cool between applications of heat. If a cyclist rides the brakes all the way down a descent, most rims will have a difficult time dissipating the heat created by braking friction. This heat finds its way to tubular glue and…game over.

Tubular tires very rarely roll when they are professionally glued. It is seen more in cyclocross than in any other discipline. I’m not a physics professor, but it is due to the high traction that lower pressures and wider tires create. This traction keeps the tire in place and under cornering forces, the tire is leveraged off the rim.

If a team finds that tires are rolling, a mechanic won’t be around long. USA Cycling used to hand out heavy suspensions to any racer who rolled a tire in competition.

I’ve never heard of pros using clinchers for safety reasons on any occasion, be it a hot day with descending or not. In fact, carbon clincher wheels have historically had their own host of braking heat dissipation problems. And I have heard of clincher tire sponsored riders switching to tubulars on climbing days.

Bear in mind that Beloki is not a big guy. His size didn’t really play much of a factor in his horrible crash. Hot tacky asphalt and misjudging his speed doomed Beloki. It was certainly a bad crash, but those occur in races all the time.

Read more at http://velonews.competitor.com/2011/01/ ... PTkbUvq.99" onclick="window.open(this.href);return false;

I've heard the line that the tyre rolled as the result of the crash rather than as the cause of it before, but what I don't know is how a clincher would have responded given the same side load. I for one am not volunteering to test it though

I have had my share of pedal strikes and slip-grip incidents, both with clinchers and with tubulars, but they clearly didn't produce the same loads that would cause "even the best installed tubular to roll" as per above? Like most of these things clearly it is possible to exert enough force, otherwise you could never remove them. But given the difficulty I've had removing some of mine, (including pulling the backing tape off one) I'm happy to believe that I am exceedingly unlikely to generate that sort of force under any circumstances whilst riding.

Cheers,

Cameron

[ironhanglider]

Further from Jobst Brandt.

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: Spare Tire (sewup) Valve Stem Corrosion
Date: 26 Mar 1999 22:09:30 GMT

Sheldon Brown writes:

>> I think it has been shown that the tire cannot come free of the rim
>> because it is constrained by the brake to lie between the fork crown
>> and rim even if the tire is not glued on and will jam the wheel.

> This may be true of newfangled bikes with the idiotic tight clearances
> currently in fashion, but isn't true of reasonably designed bikes.

Brake pads on bicycles have always been adjusted to not much more
than 1/8 inch (3mm) and that is too small for a tire to squeeze
through. Nothing new fangled about that. The tubular cannot get off
the rim because the brake caliper makes a closed envelope around it.
The other side of the tire is outside the axle and the whole thing
makes the scenario of the tire falling free of the wheel a myth.

I suppose one visualization of the event would be that the tire falls
off the rim for lack of any glue while riding straight ahead and that
it falls to the left side of the rear wheel remaining passively
hanging from the axle as it drags loosely on the ground. This is pure
wishful thinking. The tire must receive a side force to be dislodged
and that side force does not vanish the moment the tire comes off,
Hence the bare rim will slide on the road and cause a crash.

Tires can roll while riding straight ahead if, for instance the rider
lifts the bicycle while sprinting, causing a side hop. This has
occurred and the inflated tire either got pushed back on when the
dislodged section reaches the brake or it jams and blows out the tire.
I have witnessed both of these results for front wheels. Neither had
anything to do with valve caps and couldn't have.

>> If there is no tire on the rim, this makes no difference, the rider
>> will fall anyway. This has been tested. After a rider rode home on a
>> flat tubular for lack of a spare, we tried riding the bike on the
>> street and found it about as difficult as riding with a tire on ice.
>> On a hardwood floor this was even worse.

> Front wheel or rear? I'd readily believe that a front rim would be
> unrideable, less ready to believe that of a rear.

This was a front wheel. The point is that lateral traction is so poor
that it can't be ridden reasonably and I believe this is good proof
that when rolling a tire in a curve, the bicycle will fall. It is not
intended to prove that one cannot ride a bicycle on the rim under
ideal conditions.

> I must grant that the scenario of a tubular rolling and the valve
> popping out, allowing the rider to ride to a quasi-controlled stop
> is an unlikely one, but I remain unconvinced that it is impossible.

I also believe it is not impossible but find the probability so
remotely small that the concept cannot reasonable be supported as a
reason to not use valve caps. In that event one could say the same
thing about clinchers although the likelihood is even more remote.

>>> ...Rolled tubs are mainly caused by improper gluing, perhaps also
>>> by blowouts. Poor cornering technique ("lean the rider not the
>>> bike" style) would also seem to be a contributing factor.

>> Ouch! We keep getting new misconceptions into this thread. The
>> propensity for a tubular tire to roll does not change with lean of
>> the bicycle in a curve.

> Oh? They don't roll when you're riding straight. They don't roll
> when you're rounding a gentle curve at low speed so that the lean
> angle is very small. Are you saying there is some specific lean
> angle where tire rolling switches from an impossibility to a fixed,
> finite risk?

To put this into perspective, in the days when we (people who rode
bike for sport) rode only tubulars, I was descending on the local
sub=per descent rode with a bunch of bikies some of whom liked to male
like motorcycles don the hill. I and another rider changes the lead
several times and on one turn my friend passed in the last moment into
a turn so that he had to lean what surely looked like he wouldn't make
it. When we got to my house, he decided to change his front tire
because the sidewall had a nick. The tire came of with hardly any
resistance because it had been a spare and the glue did not adhere,
being too dry.

That event gave me a great understanding of rolled tubulars. It takes
a side force that occurs only when the tire momentarily loses
traction, and when recovering, receives a load that is not in the plane
of the wheel. As I mentioned, tires roll when a sprinter lifts off or
when in a curve, a side slip occurs. Neither of these circumstances
is generally recognized because the first conclusion is that the tire
came off to cause the crash when in fact it was a loss of traction.

>> Here again the image is an upright bicycle in a curve with the
>> rider leaning in so that the tire is pushed off the rim from the
>> side force.

> Some cyclists actually ride that way. You and I have both written
> extensively on the unwisdom of this, but the
> lean-the-rider-not-the-bike style is widely recommended in books and
> articles by noted racers who don't understand the dynamics of
> cornering.

That's a whole can of worms in itself but is mainly discussed on
wreck.racing.

Jobst Brandt <jbrandt@hpl.hp.com>


From: jobst.brandt@stanfordalumni.org
Subject: Re: Tubular Tire opinions wanted.
Newsgroups: rec.bicycles.tech
Message-ID: <EjSC9.49823$Ik.1294465@typhoon.sonic.net>
Date: Wed, 20 Nov 2002 20:32:36 GMT

Mark Janeba writes:

> Low inflation pressure is a common problem with tires that have
> flatted, yes.

How nice, but are you interested in the thread or is snide comedy your
aim? Most rolled tires (not flat tires) are caused by low inflation
pressure, something that occurs on MTB's more often because their
tires are often used with low pressure on soft ground. However, the
phenomenon also occurs on road bicycles and is not something
restricted to poorly glued tubulars as is often suggested.

>> It is not cornering but rather low inflation pressure, or
>> recovering from a side slip when returning to good traction.
>> Cornering forces themselves do not induce tire roll, there being no
>> side forces. Tubulars can do that better than clinchers. We have
>> seen it often enough that checking whether tubulars were glued
>> securely was a standard inspection for race officials in the days
>> of these tires.

> I'd like to hear the reasoning for this claim also.

You may have meant "Could you explain how this occurs?" "also?"

If you look at the cross section of a 25mm tire on a rim and rotate
the force vector (road to hub) around the tire cross section center,
you'll not that the tire is pushed into the rim even when the lean
angle is 45 degrees, the maximum reasonable use of a road tire. This
became evident to me when I discovered that a tubular spare tire had
not adhered to the rim when I got home after a high speed descent
leaning hard into the turns.

I have seen tires roll after a rider side-slipped across gravel and
returned to clean pavement. This can cause a tires to roll but it is
not from leaning into the turn. However, if the tire is so soft that
it deforms enough for the center of pressure to move outside the width
of the rim the tire can roll.

Jobst Brandt <jobst.brandt@stanfordalumni.org> Palo Alto CA

Clearly there was more to that thread, and I'm intrigued as to the comments about valve caps, but the short version is that cornering forces alone won't cause an unglued tubular to roll, it requires the force to be acting outside the width of the rim. Therefore if you are sensible it is perfectly reasonable to race on your spare tyre.

A few weeks ago we (tandem) punctured during the warm up for our biggest race of the year. We happened to have a spare wheel to use, but if I didn't I wouldn't have given a second thought to putting the spare tyre on and using that. I certainly wouldn't be just putting the bike in the car and driving home.

Cheers,

Cameron