kleinboogie

I have a set of 19mm wide carbon rims that, unlike my other carbon tubular rims, does not have a center channel for a tire seam to sit in (pic below, it's the rim on the bottom). I have both 21mm and 23mm Vittoria Corsa Evo CX tires and 22mm Continental Giros (I heard they have a minimal seam but it's just as big as the Vittorias). None sit well in the rim. They have a noticeable gap on the edges.

Advice from a tire guy was to build up the glue but that only marginally helped as I couldn't build it up enough to really fill the gaps on the edges.

I'm looking for tire suggestions that have no/bare minimum seam or other creative solutions.

Thanks.



Rim on top has a center channel whereas the one on the bottom does not.

Chombi

Tubular tires with beads?? I don't think they existed! My classic tubular mid 80's wheels and tires do not have these beads (only a cotton base strip glued on to the tires) and center channel you are pointing out and are only held on to the rims with glue and I guess, to a little extent, air pressure. I suspect the new tubulars worked the same way.

Chombi

Ex Pres 

Are you missing the base tape on your tires? I did buy a pair one time that had none.

Walter.dreyer

There are carbon clincher wheels, as well as "open " tubular tires. I always assumed that the "open" tubulars were for clincher wheels.

FBinNY 

Tubulars don't have beads, they're sewn into a tube and the rim is curved to cradle them

For better or worse the curvature of tubular rims varies among brands and models. Deeper rims fit narrower tires better, shallower rims fir wider. In a perfect world the curvature of the rim will match the tire mounted on it, so there's good contact over the entire width.

But the world isn't perfect and often your favorite tire and rim won't match. Years ago I used to use Fiamme rims which had very deep curvature, and my Clement Tipo 6's were nicely supported on two sides. Later on I switched to Mavic rims which have a much shallower curve. Now those same tires sat on the center with gaps on either side.

I managed (and still do) the problem by building up a bed of glue which tends to fill the gaps on either side. It's never ideal for the first tire, but after 2 or three the glue bed makes a custom fit and cradles the tire perfectly. For me old rims are like nicely broken jeans, and get better and better until they break apart.

.

reptilezs

you can also use the tape. its used for building up the glue bed. i don't use it though

ultraman6970

**********?

Just use tufo tape, 100 pounds of air and ready to go. If those dont work for you i give you 20 bucks for each rim

bikepro

Yes, "Open" tubular is a clincher, such as the Vittoria Corsa CX. They make a standard tubular and virtually identical Open Tubular version of the tire.

oldbobcat

I believe you're talking about the seam under the base tape, where the stitching is. And some rims do have a channel for the seam, but many, or most, do not.

I've rarely had problems getting most tubulars glued and seated properly without the channel, simply following the directions of the glue manufacturer. Usually the tire casing is flexible enough to adhere at the edges after inflation.

One tire that did give me a bit of trouble was a set of fairly high-priced Vredestein cottons. Stretching them over the rim, it seemed as though the tire was extremely tight around the seam relative to the rest of the casing. Perhaps they just needed a few more months of aging and stretching on old rims in a cool dark basement.

My technique is two thin even coats each on the base tape and the rim. I'm averse to stringy globs of stringy semi-dry tubular glue. The second coat is mostly to ensure coverage, but the first coat on the base tap is sometimes absorbed by the cloth. I don't attach the tire until the glue is thoroughly dry. It won't stick fast until the glue is under pressure from full inflation of the tire. If I have any concern that the glue is too dry, I'll warm it up with a hair dryer after getting the tire in place.

kleinboogie

Sorry about using the term bead instead of seam. You pretty much describe what I'm experiencing. The rims are shallow and when I put a dry tire on it fully inflated it actually rocks side to side and the gaps look huge to me. The first glue attempt was horrible. The second was better but not exactly what I was expecting. I'm going to pull the tires off and give it another go. I'm still in the learning stage and I appreciate the help and tips (I like the hair dryer idea). Cheers.

FBinNY 

I don't know what today's glues are like. I'm still using stuff I put aside over 30 years ago when I saw the trend away from the high residue gum mastics to the thinner glues which have few or any solids in them. With glues that have some solids you can mount the tire into a thick coat of glue, inflate it which will squeeze the glue to the side and set it aside for the glue to set firm enough to hold shape. Then repeat the process to make a decent bed. Or you can apply a thick of glue and spread it by running your finger down the middle making two beads on either side.

You can also use tire tape if they still make the stuff. The thickness of the tape has the effect of reducing the radius of curvature, and might make for a better fit. The last alternative, (with high solids glue) is to prime the rim with the usual two coats for a decent base, mount the tire in the usual way, and then run glue down under both sides as if caulking tile, to fill the space and buttress the tire for stability.

There were times I've considered using something like caulk and a template to recontour the rim, but it never got so bad that I felt I had to.

kleinboogie

Those are great tips and some I was aware of and others I wasn't. I think part of it is I'm running into the Art side of this and I'm still trying to figure out how to mix the paint.

I'm using Vittoria Mastik glue with an acid brush, cut slightly as the bristles were too long, and I'm finding the glue dries to a tacky consistency very quickly which makes it really messy and stringy if I don't keep moving. I found by going over an area I just brushed say 30 seconds earlier would start to create strings rather than smoothly applying the glue. I have to practice that.

I tried to use a thick coat, after a couple thinner base coats on the rim, and it really made a mess on the tire and brake track. I also tried to create a channel in a thick coat actually with a wooden popsicle stick but the resulting build-up wasn't significant to make a difference.

Do you, or anyone else, have any tips on cleaning the tire/brake surface up? It seemed that I was just smearin1g it rather than actually wiping the glue off. I'm using Acetone and Goof Off as solvents.

I also remember seeing a youtube video of a guy putting the tire on dry then injecting the glue with a syringe. I tried that to see what would happen and I quickly realized that's not for me.

Thanks!

FBinNY 

Different glues work and set differently so you have to develop a technique that works with what you have. Over the years I've found that my finger was the best spreader of everything I tried.

I never used any solvents to remove glue. I used a plastic windshield scraper to get excess old glue off the edges of the rim, and never got much at all on the sides, so let the brake shoes take care of that when it happened (improves stopping power while it lasts).

With Carbon rims be super careful with solvents because they could attack the gel coat (what it's called for fiberglass, don't know what they call it in carbon) of the carbon, or even weaken the matrix that holds it together. If you're real sloppy with glue, or until you get better, you might run paper masking tape down both sides to keep the brake track cleaner until you're finished.

One trick that I use for mounting tires to keep my hands and rim clean (and not have to shift the tire and make the glue string all over the place) is to inflate the tire so it has shape, insert the valve and stretch the tire into place working down both sides of the wheel, and finish by rolling the last section home, twisting it back so that the belly rolls straight to the center of the rim. This takes practice, and the pressure is critical because inflation makes tubulars shorter; too much and you'll never get it on, too little and the tire is too limp to work with. If you want to try this technique, practice with an unglued wheel until you're rock solid before trying it with glue.

My biggest problem with shallow rims it that the tire tends to flex onto and off the rim a bit at the edge exposing glue which would pick up sand and stones. Now with abrasive glued along the edge it would eventually cut through the walls.

My solution was to use talc to take up all the tack down both sides after I was finished mounting. The talc also had a fringe benefit in it mixed with the glue at the sides and acted like a body filler building up a berm on both sides contouring the mounting surface, so the next tire mounted that much better.

JohnDThompson 

Some track tires are made without base tape.

aixaix 

You might try getting in touch with the rim's manufacturer to see if they have any recommendations for compatible tires or gluing techniques.

FBinNY 

I doubt a manufacturer will want to get involved in gluing or mounting technique, except maybe to warn of incompatibility of various glues and solvents. As far as the tires go, it's a simple matter of matching the radius of curvature, so more deeply curved rims will favor narrower tires, and shallower rims will favor wider tires.

Years ago when there was far more product selection, track rims tended to have deeper curvature than road rims from the same maker, which made sense since they were generally used with narrower section tires. Today they don't maintain these subtle distinctions as much so it's a bit of a buyer beware situation. When I check rims I like to use a Quarter as a gauge since it's close to the width of my tires. By placing it against the rim, I can predict how well the rim and tires will match. I prefer rims where it touches at two points on either side like a V pulley, but often settle for shallower rims for other reasons.

fietsbob

AFAIK, Only with like Mavic, extruded aluminum manufacturing techniques
did sew up rims offer the double concave surface offered there
with a second concave for tire sewing seam..

older tubular rims always had just the one concave surface,
they re shaped an aluminum tube , then rolled it into a hoop.

The experience has just begun..

you got a prep layer of glue, on tire and rim, to allow to cure,
maybe a second layer on the rim, to apply and let cure,
then a layer on tire and rim to get tacky and mount the tires,
then leave them to cure for a couple days , to go..

kleinboogie

Thanks for the info. Here's a video of doing the final glue step with a syringe. I tried it but didn't know what I was doing so abandoned it. I'm thinking about giving it another try just to see if I can get better build-up than putting the tire on wet. I'd like to hear your opinions on the technique. ty

Chombi

Gluing with a syringe and the tire on the rim already???
I have not seen that either, but if it works, that's great, cause you don't have to strech a sticky glued tire over the rim anymore??
Must be a new/special glue that does not require time for setting before installing the tire??.......or I hope it is......
I use Continental tubular tire glue on my tubs these days, applied in two coats on the tire base tape and rim and tub installed after the recommended setting time written on the yellow glue tube. Old fashioned, but it works!

Chombi

fietsbob

stretch ing the tires on a spare rim is part of the thing..

then its mostly brush work , flux /acid brushes are stiff and disposable .

Tubasti out if a tube , and the brush to spread it out.
It's the traditional race tire , and no hurrying the application really works as well

you really don't want to be rolling a tire off the rim on a fast hair pin decent.

Ex Pres 

A cheaper, and for me easier & cleaner method, is to stick my index finger down into the corner of a sandwich baggie and use that to spread the glue.

Do not try [latex] disposable gloves. Or at least the ones I tried didn't work at all. The glue dried and stuck to the glove way too quickly. I've had no such issues with baggies.

Chombi

Tried rubber gloves too and they just fell apart halfway through the gluing. Just use my bare index finger now and have a rag soaked in a little mineral spirits to keep my finger and hands clean enough through the process. the bare finger gives me best control and most consistent glue distribution on the rim and tub base tape. The tub glue comes off very quickly and easily from hands and fingers with just the mineral spirits (at least Conti's tub glue does). I also use the mineral spirit soaked rag to clean off any stray glue on the rims through the process.


Chombi

aixaix 

I'm with you, Chombi, on the finger applicator technique. I use my pinkies, though: left one for front wheels, right for rears.

oldbobcat

Zipp recommends acetone and Goof-off for removing old glue from carbon rims. I've used citrus degreasers to clean my hands and the edges of my alloy rims, but I don't have carbon rims to experiment on. Anybody got a pair of 303s they're not using?

FBinNY 

As someone who's been riding tubulars since 1967, I just don't get peoples obsession with removing old glue from rims. The old glue gives you a custom bed that exactly matches the tires, plus it gives you a base texture and material that improves adhesion of newer layers. One other fringe benefit especially on eyelet rims is that it builds up around the edges of the eyelet making for a better tire seat, and reducing damage caused by high eyelets (think Mavic).

There's no negative consequences to leaving the old glue in place, and you can't see it so why the effort to get rid of it? I do understand that you might want to remove contaminated glue at the edges of the rim, bet that's easily scraped off with a plastic windshield ice scraper, or expired credit card.

It usually takes about 2-3 tire changes to get a nice glue bed on a new rim, then it only gets better with age, like old jeans. Having to establish a decent glue bed is my least favorite thing about putting a new wheel or rim into service.