I’m desperate guys. Emailed zipp themselves and they’ve been less than helpful. Tried to mount GP4000S II 23mm tires on these rims. VERY tight tolerances. Much worse than any i’ve encountered and i’m pretty seasoned at changing a tire. I’m constantly getting pinch flats right after mounting (without tire irons, just thumbs) and blow outs as the outside temp rises. I only put 95psi in them. Can anyone recommend a tire that would work better???
Basically my answers from zipp and 2 differnt LBS have been unhelpful. Both trying to walk me through how to properly change a tire (i’m well seasoned and have been doing this for years on other bikes/rims/tires, ie i know what i’m doing). Also changed the rim tape and looked for any deformity. Happens both front and rear. Has to be incompatible wheel/tire tolerance…which is why i’m asking if anyone else has these wheels…what tire do you use???
Hmmmm changed it twice. Usually when my blowout occurs its right after mounting. As careful as i am feeding air into the tube by mouth to give it definition, seating the tire, trying not to use levers so i don’t pinch and going around afterward to ensure proper seating, i still get a blowout when inflating. I only inflate to 95psi.
In 2 separate races, i raced well on the wheels and came back to pick up the bike in trandition after the tri was over, only to have tire blowouts… this honestly terrifies me…
I’m on the verge of selling the wheels if i can’t get a better answer. I know they’re old but i should be able to find some kind of solution. Happens to both front and rear.
I had the same issue with a different wheel/tyre combo awhile ago.
The tyres fit very tight and I punctured while or right after inflating every time. Inspection the LATEX tubes showed deformation along the length of the tube. After ruining three tubes I put a different brand tyre on and it worked fine. My conclusion was that the latex tube found a gap between new brand tyre an rim, small enough that the latex would stretch into the gap to breaking at about 100 psi.
I am sure butyl tubes would have worked fine since they are much less flexible than latex, but I was after low crr for racing wheels.
What tires have you used so far with the wheels? Maybe the best option is to throw away the Conti’s and go back to tires that worked well for you on the 404’s in the past. I owned the same wheels (from 2010, but I believe the rims are the same) and for me they worked well with Vredestein Fortezza’s (23mm size). I got rid of the wheels because the hubs were s**t (had to adjust the play quite often), but the rims were just perfect
Lots of replies, but none providing the answer you need. Beadjack. From Amazon, $13. A necessity if you have those old Zipp 404’s with the aluminum brake track. Makes putting on tires pretty easy.
They are super tight. I pre-stretch the tires before I put them on. It a PITA but it works. You have to use levers or you will not get the damn things on. After they are on the rims and ridden for a while getting them back on after a flat is much easier. When the tire is new is when its painful.
My first thought is the rim strip or crummy tape or incorrect tape width. I like the Silva tape and it comes in a narrower width for the older rims.
A “blow out†to me means the tire bead is blown off the rim at some point. I assume this is latex, so
have you gone around the tire before inflating to make sure you can’t see ANY tube?
Is it just one one wheel/tire (e.g., always the front)? If so the best ting is to mark the location on the rim and tire. Then check the bead on the tire for any irregularities in that spot and the rim for any bunches in the rim tape or a small dent in the rim.
Try a new tire. These things are made out of a flat sheet of material so there are overlapping areas and joins that are natural locations for weirdness. You may not be able to see these with the naked eye, but these inconsistencies exist and a latex tube will find any path out of the wheel.
buy some veloplugs, install those then run packing tape over top of it. (like a rim strip) - but if you’re getting it installed (by hand even) it’s likely not a clearance issue.
Besides the obvious latex install things to do, if you’re blowing them near the valve you need to make sure the valve stem is seated properly. On narrow older rims with newer tires there seems to be a common issue (that I’ve seen) where the tire just barely “seats” at the valve stem area, but not fully. It’ll hold air for a few minutes and then blow. To “fix” this you need to get the tube seated as normal, have the tire installed/beaded, then with just a few psi push up very hard on the valve stem. It’ll pop back up into the tire and the tire will seat properly.
Good luck, I’ve got those exact wheels and run 25c GP4000s without any issue. Specialized S-works Turbos were also easy to mount and a pretty fast tire, not super durable though
Thinner rim tape will help tremendously here. The rim tape adds diameter to the bead-seat of the rim, so using a thin tubeless tape (like ours) in 2 wraps will help with tight tires.
DO NOT use VeloPlugs with latex tubes. As they do not cover the rims surface, they do not offer any thermal barrier between the latex tube and the rim surface which dramatically increases the likelihood of a heat flat under heavy braking.
I have those rims. The channel is extremely narrow and it takes a little bit more care the ensure that the tube is seated under the tire casing. I do remember sometimes popping the tire on, checking the install by squeezing the tire and looking into the rim bed and seeing tube under the tire bead. Then I would either have to try and massage the tube under, or just redo the install. Most other rims, especially the modern wide stuff I don’t run into that issue.
What size tubes are you using? If you’re using a tube meant for 23-28 mm tires, then it may be better for you to look for something 18-23 mm instead.
they do not offer any thermal barrier between the latex tube and the rim surface which dramatically increases the likelihood of a heat flat under heavy braking.
But doesn’t the heat from braking get applied to the brake track surface on the upper sides of the rim and not the rim channel? Rim tape doesn’t provide a barrier between the tube and the inner side of the brake track, so I’m not sure how rim tape will help prevent a heat flat from heavy braking. Unless there is heat being applied to the center channel near the spokes while braking that I’m not aware of.
ETA: Or is the tire bead set to the inside of the brake track the protective heat barrier? I always thought though that the tube still touches at least part of the inside of the brake track once the tube is fully inflated and pushes the tire beads up.
