Can you run non tubless road tires tubless?

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Can you run non tubless road tires tubless?
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flag rahrider
O+
Posted: Jul 20, 2020 at 21:55 Quote
I have a set of contact speed tires by continental that are 700x42c. They are going on some old wheels that are not tubless specific (old salsa semi's) they have a hook. I'm wondering if it is ok to run them tubeless?
I've run lots of mountain bike tires over the years tubless even though the tims and tires weren't always tubless specific. Any reason I shouldn't throw some sealant in and have at it?
flag cmcrawfo
Posted: Jul 20, 2020 at 22:01 Quote
how hard / easy its going to be will depend on how well the rim and tire interface. some combinations work out great, others do not.

how much the tire weeps fluid at first will also be a factor, but with enough time, sealant and a hairdryer, you can prety much get any tire to hold air.

worst case, it doesn't work, and you just have a bunch of spooge to clean up before you put the tubes back in.

I would probably try it. Why not.
flag West24
Posted: Nov 27, 2020 at 9:14 Quote
Yes, but as a shop employee I can say not to use tubeless on a road bike. On gravel, sure, but on a road bike it cost more to setup than any advantage you could get. The only one being a bit of rotation weight, which is only a factor when pedaling. When coasting it doesn't matter. And Mr Tuffy will prevent a flat tire just as well.
flag anoplura
Posted: Nov 27, 2020 at 22:02 Quote
I've done a lot of experimenting with converting tires and wheels to tubeless, and the rule of thumb I've arrived at is that non-tubeless rims can be converted safely, but tires have too much variation, and aren't worth the risk. Use tires that are designed for tubeless, and save yourself a ton of effort and potential injury.
flag West24
Posted: Nov 28, 2020 at 12:44 Quote
anoplura wrote:
I've done a lot of experimenting with converting tires and wheels to tubeless, and the rule of thumb I've arrived at is that non-tubeless rims can be converted safely, but tires have too much variation, and aren't worth the risk. Use tires that are designed for tubeless, and save yourself a ton of effort and potential injury.

True, working at a shop we have to say "No it won't work" ONLY because if they have any problem. They can blame us for setting it up. If you are using a rim not set for tubeless and a tubeless tire. The odds of it working fine is very good. I have an old bike my daughter uses for school (1mile ride lots of dirt and rocks). It is setup tubeless with a tubeless tire. No problems in over a year. Keep it in mind that it has to bead well and for me hold air with no sealent before I will do it. By which I mean when I bead it it has to stay inflated for the time it takes to measure sealent and many times tape the other wheel.
flag holytrails
Posted: Jan 12, 2021 at 23:00 Quote
I wouldnt do it. Especially on road bike tires where PSIs are usually higher than your typical mtb tire. Tire set up is where I wouldn't cut corners to save a few dollars. If something goes wrong that's your only contact with the road, else its you and the road make contact. Don't do it. Invest in good solid dedicated tubeless tires and rims
flag R-M-R
Posted: Jan 13, 2021 at 0:52 Quote
Not safe. Problems:

1. Without a tube, the slightest flex in the bead allows pressure to apply force between the rim and bead, creating a positive feedback loop and increasing the chance of a burp or blowing the tire off the rim.

2. Tube-type beads may not fit tightly enough on the rim to provide the necessary tension to overcome the high air pressure of a road tire when problem #1 occurs. This is why tubeless beads are often carbon fibre, rather than aramid (Kevlar), or use more material than tube-type beads.

3. Tube-type tires and rims do not have a standardized set of tolerances to ensure the precise tension required for tubeless.

It would probably work a lot of the time. Half? Two out of three? Nine out of ten? When it doesn't work, though, you may end up leaving a wet streak of flesh on the road.
flag rahrider
O+
Posted: Jan 16, 2021 at 21:44 Quote
What about a gravel bike with 40-50 psi?
flag R-M-R
Posted: Jan 16, 2021 at 21:50 Quote
There's no clear cut-off at which it transitions from safe to unsafe. People were improvising tubeless set-ups on mountain bikes for years and it mostly worked. It's definitely not recommended, but the lower the pressure, the more likely you are to get away with it.

If you want to try it, which I don't recommend, start with the rear wheel, as a blowout may be less likely to cause a crash. Use wide rims to increase the lateral stability of the tire.
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