Glueing tubulars [the tubular thread]

Everything about building wheels, glueing tubs, etc.
sungod
Posts: 1415
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

jlok wrote:
Mon Jan 15, 2018 9:06 am
Hi all I'm tubular newbie. I dive into tubular sea because I'm building a new c-brake bike to join some local racing. And I think why not try to glue mine to understand why you guys are so into it...

anyway, I have already done the 1st base layer on the rim and the lovely Vittoria Corsa, and read through some pages up to ard 60...

one thing I'm not so sure is the actual mounting step below. Would the grabbing of the tire "damage" the dry glue layer on the tire?
https://www.parktool.com/assets/img/rep ... e_2-73.jpg
it shouldn't hurt the glue layer, but it's not necessary to touch the glue layer anyway - and no need for gloves, i don't get glue on my fingers, gloves just affect grip/feel and make it harder

when mounting you should be gripping the sides on the tub as you mount it, maintaining even tension as your hands 'slide' along moving the tub onto the rim

takes practice, but as i do it i can feel the position of the edge of the basetape vs. the side of the rim, this lets me adjust position as i go and get it on straight as possible before any final correction

practice with dry rim/tub a few times to get a feel for the process

by Weenie


jlok
Posts: 366
Joined: Tue Jun 30, 2015 3:30 am

by jlok

thank you sungod. I just realize that the dried glue is tacky rather than sticky so it's ok to touch (and as you said no need to touch).

jlok
Posts: 366
Joined: Tue Jun 30, 2015 3:30 am

by jlok

guys... I failed with my first attempt to install the tire. Any advice for me?

Mastik One

1. Vittoria corsa tire 170psi stretched on Bora One 50 rim (2017 24mm wide), wait for 24hrs,

2. rim and tire both one layer, wait for 24hrs,

3. rim one more layer, pumped the tire to 10psi and install tire right after, centered it, pump it up to 160psi, wait for 24hrs,

4. deflated and tried to pull it off by hand, found that the tire was not 100% sticking from the edge... disappointed of course...

results as below... I think the big problems are that I didn't use enough pressure pulling the tire down from the valve... and 1 UNEVEN layer of glue is not enough... sections around valve hole just didn't stick.....

can I try again with the current condition? is the tire shot?
I got the effetto mariposa carogna remover. Should I use it on the rim to clean and do the gluing again? Want to try 2 layers... real nice and even......

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sungod
Posts: 1415
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

from the pictures, a few comments/suggestions...

the tub is fine, wipe the tape/glue over with a clean cloth and some acetone, just to remove any trace of grease, then give it another coat of glue, the areas where the coating on the basetape peeled off may be a bit 'thirsty', be prepared to touch them up with an extra layer

if there're large areas where the rim is bare i'd suspect it still had some mould-release compound/other contamination on it, in which case strip it, clean thoroughly and reglue - fwiw on a new rim i use some 0000 steel wool to help scrub the surface of any waxy compound (this is not to roughen it, and don't go mad and take off the clearcoat), then use acetone and/or isopropanol with clean paper towels to scrub it until the towels stay clean

if the glue on the rim is ok, just put an extra coat on, working it in to the previous layer, let it dry a few minutes, remount

once the tub is on and lined up, i deflate it and then using a pole/other long blunt 'edge', roll the wheel along it applying pressure to force the basetape hard against the rim, then inflate, final check alignment is still ok and leave it to dry

try inflating to a lower pressure than you used, say 6 bar, if the rim/tub profiles don't match then very high pressure may tend to lift the basetape away from the rim either at the centre or the edges

with the current corsa tubs, i found i had to apply a lot of pressure at/around the valve area as it bulges a bit more than, say, veloflex ones, the bulge can result in a 'tic' each revolution - the first time i used them, after a few days i had to take them off and reglue as it was so annoying on quiet roads

when remounting i first pressed down hard on the valve area with the heel of my hand, then got the tension as high as i could while getting the tub on, being more generous with the glue for 3-4cm each side of the valve may also have helped, either way both wheels were then 'tic' free

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