jtree

i glued up my first set of tubulars using the colin s. howat instructions. 3 thin coats extending all the way to the edges of the rim allowing the first two to cure and one coat on the base tape. but according to the park tool website i got some starved joints:



my rims are campy neutrons and i'm using veloflex carbons. so i pulled the tires off the rims. it looks like the base tape was mainly held to the rim along the center line of the base tape because along the center line of the base tape i can see white spots where the glue pulled off. along the edges of the base tape the glue is pristine.

now how should i proceed? are neutrons and veloflex carbons known to be a bad fit? my thought is to try to build up the glue near the edges of the rim with a couple more coats and leave the center of the rim as is. will that be too much glue?

DiabloScott

No that won't be too much glue. New rims sometimes take quite a bit and you probably just got it a little thin near the edge. Take off the tire and keep it clean, smear some new glue on the rim with your finger in a baggie and get it kind of thick near the edge, let it sit about 15 minutes, remount the tire, straighten it and press it up to max.

Did you stir the glue up good with an old spoke or something first?

jtree

i'm using vittoria mastik one and for the first two coats on the rim and the coat on the base tape i didn't mix it. that used up a whole tube even though i really tried to put on thin coats and i didn't notice any separation in the glue. for the last coat on the rim i had to start a new tube and i mixed it with a spoke first.

lotek 

I don't recall if it's Veloflex of one of the other brands of tubulars
but one of them has a layer of latex(?) on the basetape when you purchase
them, and the theory is that the glue disolves this and impregnates the base tape.
Does that always work? I don't know but I suspect it also is dependent on the
formulation of the glue.
The general wisdom on this type of tire is to scrape the latex off the base tape
and then apply the glue.
fwiw when I apply glue to the tire I use enough glue that the tape
takes on a buttery colour, and I use 2 thin layers on the tire. let it dry
about 15 minutes (or until just tacky) and then mount the tire onto pre
glued rim. Center the tire etc. and then pump it up to full working pressure
and let it sit a good 12 hours.
works for me every time.

marty

jtree

i tested the base tape on the veloflex carbons by scraping it with the edge of a butter knife and nothing came off so i assumed there wasn't any latex on the base tape.

ok. that's the way mine looked. a golden butter color.

dang. those phd's say to use only one layer on the tire. but i've also read that some base tapes absorb so much glue you need to use multiple coats. any experience with veloflex?

Cleave

Did you pump up the tires to max pressure after seating and centering them on the rims? That is something that I learned to do in the 1970s. If you do that before the last coat of glue completely sets you shouldn't end up with what you show in the photo.

jtree

yes. i also pushed down on the axles while rolling the wheels on the floor to seat the tires properly per the instructions before inflating to max.

if i brake while going down a long hill will that cause the glue to melt and flow around the tire and adhere better?

lotek 

I've never used that particular method, what I would do is pull the tires and reglue them. a bit of a pita
but I'd rather be safe than sorry.

marty

DiabloScott

That's exactly the wrong thing to do. You're right, the glue will soften but the tire will shift on the rim and if it goes too far it'll rip out the valve and you'll have a blow out. Always try not to heat up your tubular rims - feather your brakes etc.

I think you just need more glue. One tube per wheel on a new set is completely normal.