Is there any problem with running tubeless on non-tubeless rims?

Question

I have Fulcrum 5 DB wheels, which are not tubeless ready. My previous wheelset were tubeless compatible and I've been impressed with running tubeless.

So my question is: Assuming I can mount my tubeless tyres on the new wheels and can get them to seal and not leak air, is there any reason I shouldn't run these wheels tubeless? Is the rim going to 'hold' the tyres less tightly and cause roll offs? Is there something else going on with tubeless compatible rims that I've missed?

My tyres are Schwalbe Pro Ones

Answer 1

One of the considerations (assuming you are able to get a good seal) is that air loss under a tire burping may be worse than a tubeless specific rim. In CX this is definitely a consideration, especially if you are pushing the lower limits of tire pressure (e.g., < 30 psi on 700x33c is amazing on slick off camber turns, but it is easy to fold the tire in a hard high traction turn). A large burp could drop the pressure dangerous low, resulting a loss of control and injury.

For running on the road, it is unlikely you will want the pressure at such low levels, so burping events are much less likely. [DISREGARD - see Update]

Update - Nov 28, 2016

Found this quote from Lennard Zinn:

When using road tubeless tires, I recommend using tubeless-specific rims. For the lower pressure of mountain bike tires, I think, other than a bigger burping issue on corners due to the lack of the bead-locking “hump” on the medial edge of each bead shelf, that tubeless conversion with most rims is fine.

Read more

For road bike applications, Lennard recommends only using tubeless-specific rims, but for mountain bikes (read larger volume tires) this is not always necessary depending how low of a pressure you are running and how aggressively you are riding. Similar to my initial answer, Lennard also points out you stand to lose more air in a burping event.

Thinking about Lennards answer some more, I suspect his recommendation for road tubeless has to do with a lower margin-for-error with a road tubeless tires. You are dealing with smaller air volumes, and are much more susceptible to negative consequences associated with air loss events.

For example, you could have a poor rim/tire seal. It seems to hold air at initial inspection but it is in fact slowly leaking air. Air loss during a ride could result in the bike becoming uncontrollable. With a larger volume tire, slow air loss is less of an issue because your margin of error is larger. Small volume tires could reach critical pressure levels much quicker than a larger volume tires under the same poor seal scenario.

Because road tubeless tire a smaller pressure buffer, mistakes in your setup become critical to safety as critically low pressures can result in a bike becoming uncontrollable.

Conclusion

I would follow Lennard Zinn's advice and only uses road tubeless tire with a tubeless-specific rim.

Answer 2

I am currently running tubeless tyres (Maxxis High Roller LUST) on non-tubeless rims- it is working just fine and has been for a number of months now!

The main thing that needs to work is the initial seal. For some reason, when I installed the tyres, I didn't get the typical pop you associate with the bead seating itself on a tubeless setup, and I can only assume this is due to the fact the rims do not feature the slight lip of tubeless ready profile rims. However, the advantage of my setup is that the tires are quite chunky and sitting on fairly narrow rims so I think the bead has essentially squished itself into the rim seating. As I've said though it is holding very well- I've even burped them once or twice and the seal has held just fine.

So from my personal experience, it's completely doable, however I think it would be dependent on the tyre/rim combo.

Note: Prior to buying my current tyres I tried to set up my non-tubeless rims with non-tubeless tyres. Surprisingly, the only thing that prevented this working was existing holes in the tyres. It is entirely possible the whole tubeless-ready idea is another bike-industry gimmick.

Answer 3

I've used tubeless tyres on non-tubeless rims on the road three different setups:

1. Vision Team 35SL 17mm inner rim with 26mm pirelli p zero.
2. Fulcrum wheels (forget which ones) 16mm inner rim with 26mm p zero.
3. Mavic Cosmic Exalith Pro 52mm 18mm internal rim with 25mm GP5000.

No issues. Just make sure you use a good tubeless tyre and in my experience it works fine. I always pump them up and make sure they hold overnight first and then start cautiously when I first ride.

I also ride them well below 100psi. Usually I'll try to keep them below the magic 72psi of hookless rims or very close to it as it was engineered with tolerance obviously. So I figure if you're using tyres that can be used hookless and you have a rim that has a hook, if you can get them to inflate and the bead sits below the hook then surely that's safer than not having a hook? I never ran the Visions with inner tubes. I went straight to tubeless and I've had them over a year and over a thousand miles.

The tyres are worn out and need changing now, so it worked as intended. I think the bike industry hypes a lot of stuff. Some tyre and rim combinations won't work on actual tubeless rims and some will.

The main thing is you have a good tyre that won't stretch and is compatible with the way your tapes installed and inflates. I like my tape to literally stop 1mm or 0.5mm away from the bottom of the hook on a none tubeless rim. This means the tyre will press into the tape and seal but also be rubber on metal for the tyre to grip the hook and sit securely. I found you need a pump with a pressure cylinder on there to blast the tyre under the hook during initial installation. Track pumps are no good on tubeless rims in my experience.

But disclaimer - I'd exercise caution with ANY tubeless setup at first, especially hookless tubeless and non-tubeless rims run tubeless. I have both and haven't had issues personally but we have all seen even tubeless rims in pro racing go horribly wrong.

Good luck people. Be safe and have fun.

Answer 4

I've been doing exactly what you're doing:
'regular' road clinchers with Schwalbe Pro One Tubeless tires ... and running them as tubeless. Yes, it's possible. Yes, it's safe. The key point is the Tubeless tire! The rims are [mostly] all very similar but the key is to have that first seal (i.e., the seal which occurs when you first set up the 'regular' rim and the tubeless tire). You'll know if it's holding air, ... within 10 minutes it'll either still be full or will have lost air within 45 seconds. Yes, run it with sealant! The sealant is used to stop air loss: at the rim strip, out of the tire pores, and out of the rim/tire bead contact area. The 'SNAP' people are used to is due to the tubeless tire running in the inner channel of a tubeless rim and then hitting X pressure and snapping up out of the channel and against the side of the rim (where the tire bead sits against). With a 'regular' rim, the inner channel is missing so the tire simply slides out gently and slides into position. This though will only work if the tire is sitting somewhat taught against the 'tubeless tape' sealed rim. Yes, the rim bed needs to be 'sealed' (e.g., Stan's No-Tubes tape is some of the best, and two layers of tape helps make the tire beads tight even in a regular rim).

The comments about pressure differences are indeed [mostly] correct. Mtn bike speeds are not as high which means the air pressure won't exert as much force against the tire to stretch and jump over the top of the rim. The risk between the two disciplines is the same, but the likelihood of catastrophic failure while using non-tubeless rims and non-tubeless tires is much lower if trying to cobble together mtn tubeless versus the higher likelihood of failing with road tubeless ! Key Learning: ONLY use tubeless tires for road tubeless!!!! (and pump them up to a reasonable running pressure) The risk we all face is having the tire bead roll off (same problem we faced in 1985). The tubeless tires though avoid this problem due to carbon beads whereas 'regular' tires use steel or aramid / kevlar beads. Carbon beads don't stretch, aramid / kevlar beads do stretch. Manufacturers and industry participants are protecting their liability and their products. Therefore always consider the source of any comments (they aren't necessarily wrong but the speakers have a vested interest in having us chose their direction). For me, I care about the facts, the numbers. Incredible these 'experts' can't agree on a standard, ... oh, something like say Road UST. Just do it already. The many different Tubeless Compatible, Tubeless Ready, No-Tubes systems... the reality is they all adhere to a different 'standard' (if you care to call it that). Unfortunately, it comes down to who is holding which tape measure while they build and label their parts. Hmmm, again it sounds like 1985.

The final decision is always our own. I typically start slow and gain some experience on any new gear after I've read everything possible about the real numbers!!!!

I am of course always willing to ingest additional information so if anyone has any 'real' information / numbers, please do advise.