Is sealant really worth it?

[MikeD]

Originally Posted by redir

One thing to consider is that using sealant it probably a safety concern. Imagine bombing down a mountain and getting a flat in a corner. The sealant might just keep your rubber on the road. That's what I like about tubular tires and one of the reason why I almost exclusively ride them on the road.
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Unknowable. It could easily be no more or even less safe. I.e., slippery sealant spewing out over the tread/road, large puncture losing pressure as fast as a tube, burp after hitting a rock or pothole (no burp with tubes). Vittoria inserts may help, but cornering hard on about a 20psi tire equivalent is probably not controllable.

[Spdntrxi]

Originally Posted by MikeD

Unknowable. It could easily be no more or even less safe. I.e., slippery sealant spewing out over the tread/road, large puncture losing pressure as fast as a tube, burp after hitting a rock or pothole (no burp with tubes). Vittoria inserts may help, but cornering hard on about a 20psi tire equivalent is probably not controllable.

inserts never designed for that... just to get you home. I've road on them (and fast) 15+ miles. (no hard cornering)

[Likes2ridefar]

If you manage to burp your tubeless tire on a hard enough hit such as a pothole or rock chances are you will ruin a tube, too, which will deflate much faster to flat than a burped tubeless tire in most cases.

I did this last year on my new mtb before moving to better, wider wheels. A hard hit pinched the tire against the rim creating a hole near the bead. It leaked slowly and I was unaware as I continued a fast descent and didn’t realize until the aluminum rim repeatedly took hits against rocks. Stopped and sealant was leaking/bubbling out the side by the rim and it eventually stopped without a plug by packing some dust from the trail over the hole and a lot of pumping with my hand pump

[benb]

I have always thought if you manage to do any of that you screwed up in one of the following ways:

- Not enough tire for your application
- Not enough tire pressure for that tire/bike/rider weight combo
- Not enough tire/pressure for that trail/condition/level of aggression
- Not enough suspension for the combination of the above if your suspension is not helping protect the tire

These super aggressive Pro MTB guys are running big tires, inserts, and more air than us less aggressive MTB riders IIRC, partly cause they have more suspension and they know the tire can't be used to suck up that much of a hit.

More recently I've been learning about how if you run your suspension with too much sag the spring rate on our typical air forks/shocks ends up ramping up *faster* because you have excessive sag. If you do this the fork/shock acts like it has more high speed damping because the spring rate ramps up faster, which will then cause your tire to take more of the hit. I have definitely been guilty of this in the past.

So if you run suspension too soft and then keep reducing tire pressure to try and balance out the fact the suspension acts too harsh you put yourself at more risk of bottoming out the tire and/or burping it.

Then of course you use all this to justify buying carbon rims cause they are stronger and can handle you running too low pressure for your chosen tire/weight/behavior.

Now rigid bikes have no suspension, so if you're having any of these issues it's just not enough tire.

[Likes2ridefar]

I would generally agree but there is the **** happens component like a pot hole or major hit on the trail that any amount of pressure won’t save the tire or tube.

In my example above it was because I did not have enough tire pressure for aggressive riding down a very rocky trail that has a reputation for destroying tires regardless of what tire you run. It was one of my first rides on a mtb after years on a gravel bike that didn’t have suspension so I was more careful in what I hit and ran very low pressures…not a good model for a FS mtb but is what I used.

It’s still my proving ground for if a tire survives PHX mountain preserve aggressive riding it should be safe pretty much anywhere I’ll take it and therefore I feel more confident in the remote desert.

[Mark McM]

Originally Posted by Likes2ridefar

If you manage to burp your tubeless tire on a hard enough hit such as a pothole or rock chances are you will ruin a tube, too, which will deflate much faster to flat than a burped tubeless tire in most cases.

I don't believe this. Many times I've been on MTB rides in which riders burped their tubeless tires, while riders with tube had grass and leaves trapped between their tires and rims yet got no flat tires. For grass and leaves to get trapped between the tire and rim, the tire had to have been pushed away from the riim, the same as the tubeless tires that burped.

[Likes2ridefar]

Originally Posted by Mark McM

I don't believe this. Many times I've been on MTB rides in which riders burped their tubeless tires, while riders with tube had grass and leaves trapped between their tires and rims yet got no flat tires. For grass and leaves to get trapped between the tire and rim, the tire had to have been pushed away from the riim, the same as the tubeless tires that burped.

Interesting. I admit I’m having a hard time understanding how grass and leaves getting stuck between the tire and rim is similar to a hard, unexpected hit on a pothole or rock. I did used to live on the east coast and mostly only mountain biked for 10 years during a period when tubes were common and tubeless was just coming out but didn’t really work that great so i mostly used tubes, too. I don’t recall that scenario or people with me but do recall many flats usually because too low psi for the trail conditions…I was on a rigid single speed mostly so any cushion was nice on rocky trails.

[bigbill]

Originally Posted by Likes2ridefar

Interesting. I admit I’m having a hard time understanding how grass and leaves getting stuck between the tire and rim is similar to a hard, unexpected hit on a pothole or rock. I did used to live on the east coast and mostly only mountain biked for 10 years during a period when tubes were common and tubeless was just coming out but didn’t really work that great so i mostly used tubes, too. I don’t recall that scenario or people with me but do recall many flats usually because too low psi for the trail conditions…I was on a rigid single speed mostly so any cushion was nice on rocky trails.

I've burped a MTB tire and had it reseat at a lower pressure. I ended up using a mini-pump to pump it back up until it felt like the other tire. So, the fact that it could briefly unseat and reseat means that getting debris in the bead is realistic. Mine occurred in the desert so maybe I got some sand or gravel, but nothing that prevented it from reseating.

[Seramount]

will pass on tubeless, disc brakes, sloping top tubes, electronic shifting, gravel, uber-wide tires and whatever else doesn't fit in my curmudgeonly retrogrouch world.

ymmv

[charliedid]

Originally Posted by Seramount

will pass on tubeless, disc brakes, sloping top tubes, electronic shifting, gravel, uber-wide tires and whatever else doesn't fit in my curmudgeonly retrogrouch world.

ymmv

Shocking!

[Louis]

Originally Posted by charliedid

Shocking!

Perhaps even bone-shaking...

[Mark McM]

Originally Posted by Likes2ridefar

Interesting. I admit I’m having a hard time understanding how grass and leaves getting stuck between the tire and rim is similar to a hard, unexpected hit on a pothole or rock. I did used to live on the east coast and mostly only mountain biked for 10 years during a period when tubes were common and tubeless was just coming out but didn’t really work that great so i mostly used tubes, too. I don’t recall that scenario or people with me but do recall many flats usually because too low psi for the trail conditions…I was on a rigid single speed mostly so any cushion was nice on rocky trails.

Tire burping is not from direct impact - it is from large momentary side loads, that literally "yank" the tire laterally to the side and away from the rim's sidewall. When the tire is pulled away from the rim's sidewall the pneumatic seal is broken, and air can escape. Burping typically only happens at low pressure, when the pneumatic pressure is too low to keep the tire firmly pressed against the rim sidewall. This momentarily tire pulling away from the sidewall can happen with tubes also, which is how leaves and grass can enter into the rim cavity, and then get trapped between the tire and rim once the tire "snaps back". The rush of air during a tubeless burp may prevent debris from falling into the tire.

[charliedid]

Originally Posted by Louis

Perhaps even bone-shaking...

That's the post of the day.

[trener1]

Originally Posted by Seramount

will pass on tubeless, disc brakes, sloping top tubes, electronic shifting, gravel, uber-wide tires and whatever else doesn't fit in my curmudgeonly retrogrouch world.

ymmv

I don't understand, you should be passing on any type of shifting, if you want to be a true retro grouch

[makoti]

Originally Posted by trener1

I don't understand, you should be passing on any type of shifting, if you want to be a true retro grouch

Not to mention responding on stone tablets