pstock

Trying to mount tires on two nice old (6 speed) Campagnolo hubbed clinchers.
A 700c tire fits easily into the rear Ambrosia rim.
But trying to fit a 700c tire on the front wheel, a Campagnolo Omega rim, is basically impossible. (I was able to force one 700c tire using steel tire irons but then realized "this is useless. What would I do if I flatted on the road? I wouldn't be able to get the tire off")

Could this front be a 27"? Doesn't look like it. When I hold them.vertical against a wall and drop a square, the diameter seems to be identical. The pencil mark lines up for both rims.

So what other explanation could there be?

What else can I try? I've got about 2 dozen used 700s. Just keep trying them all, like Cinderella and the slipper?

AnkleWork

Compare the markings on the old tire with the new tire?

JohnDThompson 

Campagnolo didn't make 27" rims. You just have a tight tire/rim combination. I have the same rims, with Continental tires installed. I don't remember any particular difficulty mounting them, but because of arthritis in my hands, I do use a bead jack (better than tire irons, as there's no risk of puncturing the tube when installing). VAR makes a portable bead jack/tire lever combination you can carry with you:


https://www.retro-gression.com/produ...tire-bead-jack

DiabloScott

New tires are always tougher to install than used ones - so after you've had it on there a while it shouldn't be a problem if you need to fix a flat on the road.

But a stretching technique I've used is to install the tire without a tube - so you don't have to worry about pinching it, and you can use your regular levers to get that last bit of bead on. Then you can go around the wheel with the levers and work some slack into the bead on both sides. Then put in the tube and re-install with just your hands.

sch

Had a similar experience with some Contis recently, 3 "made in Germany" were impossible to mount without 30 minutes of wrestling
on a Vuelta wheel. OTOH same tire(s) mounted easily on a Rolf tandem rim in about 2 minutes. A 4th Conti (Ultra Race) made in SE
Asia, mounted with little difficulty on the Vuelta, where it is now. A Michelin Pro4 that was on the Rolf also easily mounted on the
Vuelta. Some combos can easily be mounted with thumbs only, some will break a few tire tools getting them on and will require
divine intervention to remove in case of flat in the boonies. Took my thumbs 3-4 days to recover from wrestling with all the tires
and wasted 3-4 hours overall on the experience.

ThermionicScott 

What rim tape do you have in there?

canklecat

Continental Ultra Sport 2 tires are why I now have a Kool Stop bead jack. Good tires for the money but when I tried to install them using a plastic tire lever to horse the bead over the rim I nicked a tube. The bead jack is easier and minimizes the risk of nicking a tube.

On the same rims (older Araya CTL-370) I could install Vittoria Zaffiros without trouble. Schwalbe One V-Guards were tough to install when new but got a bit easier the second or third time. The Contis don't get easier.

No problems with Conti Speed Rides on my hybrid rims. The complaints about Conti tires being super tight seem to be confined to their road bike tires.

andrewclaus

I have one rim like that, and at least one tire brand does not mount on it. It was given to me by someone who repeated broke and bent tire irons on it, but I'm able to use it with the right tire.

Nice trick above, not using a tube at first with a new tire.

Another trick is to pinch the two beads into the center of the rim, where the diameter is often a mm or so smaller. Use both hands to squeeze the tire into the rim around the mounted circumference. That extra mm can make a big difference.

And recently I've been finishing at the valve stem, in order to allow the beads to seat into the center of the rim more fully (another tip I heard here). It works if you're careful not to damage the stem.

ExPatTyke

Agreed - I had Gatorskins on one road bike, and have US2s on another. They're the hardest tyres to fit that I've ever used.

leob1

Some tire/rims combos are just tough to get on. Some slip right on, some you have to fight every inch. In addition to the tips listed, lube the rim and tire with dish soap. Just give them a thorough rinsing after you get them on and inflated.
They will loosen up after being ridden on a while.

fietsbob

the bead seat interface of tire and rim has variations from a precise 622mm diameter, over a million tires & rims made..



Design matters..drop center Wolber super champion 58 rims were easier than Mavic ma40 double wall .. for examples..






...

pstock

Yes, that would make life simple.
But I got these wheels naked, without tires.

Nor are there any markings on the rims to guide me.

pstock

FWIW all my two dozen tires are used. Most are well well used. I am just trying to find one that fits.
and I would still be anxious about trying to remove a tight fit if I flatted.

As I said, last night was able to force a tire on. But then thought I'd better check if I can even remove it. After snapping in two a plastic tire iron, I went back to a couple of old steel jobs. But their somewhat blunt lever ends were impossible to get under the beads.
I had to grab the empty tired with vice grips, pull hard on that to get a little gap showing that I could get a tire iron into.
That is not going to work on the road.

pstock

So THAT's what that tool is? I used to have a tire iron like that and I had no idea one end was a bead jack. I am getting more of those.

(and good to know about Campagnolo not having made 27" rims. I suspected as much.)

pstock

These particluar rims don't have a lot of depth to them. the cross section bottom seems pretty flat. Though I was wondering one was shallower than the other (so the distance from the middle of the "bottom" of the rim on one side to the outer edge on the opposite side would be greater (and so would make it all feel tighter)

But measuring (those depths), there only seems to be a single mm difference, if that.
(Though that might be enough.)

shoota 

Consider yourself lucky that the Ambrosio rim is easy to mount a tire onto. I had two of those rims that were basically impossible with ANY tire I tried. I sold the wheels.

Drew Eckhardt 

Something is wrong if you can't get the first bead on. Assuming you can:

1. Finish the second bead at the valve stem, starting 180 degrees away from it. You'll have less slack when you can't move the bead to the center of the rim.

2. Begin by moving the bead to the middle of the rim extrusion, then maintain tension pulling the bead into the depression as you milk the slack around until you can finish with your thumbs.

3. Use two wraps of 1 mil kapton tape (totaling .005" versus .020" for Velox) if you have a tight combination; 16mm / 5/8" for classic rims, 19mm / 3/4" for somewhat wider.

Together, those things can make the difference between cussing at tools and comfortably hand-mounting tires.

davidad

https://www.amazon.com/Zefal-Twin-Bi...fal+tire+gauge

pstock

thanks for the suggestions.

I worked through a few more tires. Finally I was able to force one bead fully on, but that required using tire levers to get it on.
I am stuck on the 2nd bead now though. I am down to about6inches of bead exposed but it is now so tight against the rim that I cannot even force a tire iron in there to pry it on.

and again, this is just an experiment basically. Even if I got it fully on, I would then be trying to remove it, to be sure I could if I needed to out on the road.

I don't know....

the rim tape doesn't have a brand marked on it but it seems to be the light, then plastic snap on stuff.

I'm looking around for a bead tool, but again, if I had to use one, I'd be worried that I wouldn't be able to get it off, once out on the road.