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gregk wrote:
Which one do you think will be easier to deform by pressing it with your thumb? The racing tire, of course. Now think of the road as your thumb, and repeat the process at 25mph for an hourâ€¦ all of a sudden that extra resistance adds up.

That doesn't explain the full picture. You can cause a stiff slow tire to give way to your thumb just as far as a supple tire by pumping it to a lower pressure, yet this causes hysteresis losses to go up.

When two tires are pumped to similar thumb-squishiness, the thing that makes the supple tire faster is that less of the deformation is taken up by lossy tire elements, and more energy gets returned to forward motion when the tire rebounds.
Last edited by: HTupolev: Sep 4, 19 8:23
HTupolev wrote:
gregk wrote:
Which one do you think will be easier to deform by pressing it with your thumb? The racing tire, of course. Now think of the road as your thumb, and repeat the process at 25mph for an hourâ€¦ all of a sudden that extra resistance adds up.

That doesn't explain the full picture. You can cause a stiff slow tire to give way to your thumb just as far as a supple tire by pumping it to a lower pressure, yet this causes hysteresis losses to go up.

When two tires are pumped to similar thumb-squishiness, the thing that makes the supple tire faster is that less of the deformation is taken up by lossy tire elements, and more energy gets returned to forward motion when the tire rebounds.

That's the best I could do in terms on an analogy that'd be super tangible for a non-technical person. Fail! ;) If you can come up with something better and equally bite-size, I'm more than open to suggestions.

EDIT: I ended up adding a clarifying sentence, along with a link to the article Tom mentioned a few posts down from here.
Last edited by: gregk: Sep 4, 19 12:05
P.S. Any time I mention the words "rolling resistance" in an article or forum post, I feel like I'm walking into a lion's den of killers with a steak tied around my neck ;D
gregk wrote:
(To all):

We just posted a new home page article relevant to this tubeless discussion, about tire pressure and Crr (rolling resistance). The original article was actually intended as a tire pressure guide of sorts (referencing our recent tire pressure poll, and the same poll ran in early 2017). However, in the process of writing, it became apparent that there was just too much info on rolling resistance that had to be covered first. In other words, Crr is too complicated to explain in a paragraph or two as part of a tire pressure article. So, I split it up into two different articles, and the second should be out later this week (the one that's actually about determining your best tire pressure).

Now, I want to be clear that my article today would not have been possible without the assistance of great resources like Tom A, Al Morrison, and Silca / Josh P. I link back to an article on the Silca blog which goes in to great length and detail on Crr and Impedance. If you've read any of my stuff, you'll know that I'm typically trying to take really complicated topics and 'detune' them a bit to be understood by a wider audience while still being accurate. You know, analogies and blah blah blah... hopefully the article helps at least some of you ;)

Don't forget to link to that previous ST article on Crr from back in 2007 which explains the source of it a bit as well: https://www.slowtwitch.com/...ling_events_226.html

http://bikeblather.blogspot.com/
Thanks - I'll toss a link in later today!
ironmanrex wrote:
Dan, after reading about your front page article; you got me thinking about converting to tubeless for my rim brake road bike which is primarily used for riding in the mountains. I use Hed Ardennes Black wheels and sometimes Bontrager Aeolus XXX 2. For the optimum set up, which tire would u recommend and what tire pressure? (Iâ€™m 135 pounds if that matters)

Thanks

We just published our second article (the first being the rolling resistance piece), covering the factors to consider to arrive at your best tire pressure. The HED chart shown is my go-to baseline for setting pressure, and then I adjust from there based on all of the other factors mentioned in the article (i.e. road surface conditions, rider weight, etc). The only caveat is that the HED chart is effectively off one tire size compared to actual inflated size (i.e. what they're listing as a 23mm tire inflates to an actual 25-26mm on their wide rims... so that's akin to using an actual 25-26mm tire on a skinny rim).
gregk wrote:
ironmanrex wrote:
Dan, after reading about your front page article; you got me thinking about converting to tubeless for my rim brake road bike which is primarily used for riding in the mountains. I use Hed Ardennes Black wheels and sometimes Bontrager Aeolus XXX 2. For the optimum set up, which tire would u recommend and what tire pressure? (Iâ€™m 135 pounds if that matters)

Thanks

We just published our second article (the first being the rolling resistance piece), covering the factors to consider to arrive at your best tire pressure. The HED chart shown is my go-to baseline for setting pressure, and then I adjust from there based on all of the other factors mentioned in the article (i.e. road surface conditions, rider weight, etc). The only caveat is that the HED chart is effectively off one tire size compared to actual inflated size (i.e. what they're listing as a 23mm tire inflates to an actual 25-26mm on their wide rims... so that's akin to using an actual 25-26mm tire on a skinny rim).
Not sure where best to comment on the article. One thing I noticed that should at least be considered when choosing pressures for road bikes is that the weight distribution is not static and while rear heavy, is shifted to the front of the bike when it is most critical ie during hard braking and turning where a pressure set based on a lower fraction of the weight may lead to a critical rollover or unwanted carcass flex. I used to run much lower front pressure based on that ROT, but had a scary incident with that(maybe too low of pressure even without a bias) and have since started running equal pressures
redlude97 wrote:
Not sure where best to comment on the article. One thing I noticed that should at least be considered when choosing pressures for road bikes is that the weight distribution is not static and while rear heavy, is shifted to the front of the bike when it is most critical ie during hard braking and turning where a pressure set based on a lower fraction of the weight may lead to a critical rollover or unwanted carcass flex. I used to run much lower front pressure based on that ROT, but had a scary incident with that(maybe too low of pressure even without a bias) and have since started running equal pressures

Interesting. Never really heard of that. I don't do a big difference front/rear... usually about 2-3%.
gregk wrote:
redlude97 wrote:

Not sure where best to comment on the article. One thing I noticed that should at least be considered when choosing pressures for road bikes is that the weight distribution is not static and while rear heavy, is shifted to the front of the bike when it is most critical ie during hard braking and turning where a pressure set based on a lower fraction of the weight may lead to a critical rollover or unwanted carcass flex. I used to run much lower front pressure based on that ROT, but had a scary incident with that(maybe too low of pressure even without a bias) and have since started running equal pressures

Interesting. Never really heard of that. I don't do a big difference front/rear... usually about 2-3%.

I don't base my front/rear pressure difference off of static weight distribution, for exactly what is mentioned by redlude97, i.e. weight transfer under braking/turning. I'm pretty sure that's what Josh P. does as well...

http://bikeblather.blogspot.com/
gregk wrote:
Interesting. Both you and Tom were using Orange Seal, which I haven't used for any significant length of time on a personal bike. I've heard from reputable sources that their current formula seals better than just about anything out there, but that it also dries out more quickly than other sealants (and needs to have sealant added more often). The experiences you and Tom mention line up with this, but I suppose I hadn't foreseen that it would become a solid 'puddle' in the tire. Usually for me, sealant just tends to 'disappear', or sometimes form in to some loose chunks that roll around in the tire.

The experience convinced me to convert my gravel bike back to tubes for the winter. When the spring gravel season starts, I will go back to tubeless for the races.
What am I doing wrong?

I'm on my 4th (fourth!!) attempt to run a tubeless setup on my Cervelo S5, with Conti GP5000TL on Mavic Cosmic Elite UST wheels. The tyre inflates properly with little effort, seat properly and seem to seal around the rim. I can't hear any hissing, but the tyre deflates slowly overnight. This only happens with the rear wheel - the front sealed first time and has been problem free. And other tubeless wheels I own have been easy to set up. So hopefully I'm trying to do this correctly!

I've tried the originally installed Mavic tubeless rim tape, and 3 attempts with others. I've installed the tape and then left it overnight with an inner tube inside to help the tape adhesive bond to the rim.

I'm using the Mavic shaped valves which are designed specifically to match the centre channel on the rim.

I'm using 18mm tubeless specific rim tape which fits neatly into the rim. The rims have a specified 17mm internal width, but that's between the outer edges of the braking surface, not the tyre bed, which is slightly wider.

There's plenty of sealant in the tyre (40ml), and I'm shaking/bouncing/riding the tyre in every orientation to ensure it's available at all possible leaking points.

I *think* what's happening is that imperfections in the rim surface (there are a couple) make it impossible for the rim tape to stick properly, and the air/sealant just sneaks underneath at these points, leaking into the interior of the rim - there's no leaking sealant visible externally.

Any ideas for what else I could do?

Or should I simply return the wheel to the vendor, on the basis that it doesn't perform as advertised.
Try spraying some soapy water on it and watch for where it bubbles. If it's through the rim this might be trickier but you might find out if it's coming from a spoke hole (assuming they're all soaped), you just won't know which outer rim hole.
I think your guess on imperfect rim surface is right. I had ~the same experience recently, and LBS agreed it was likely imperfect rim surface.

But I was actually able to locate a very low hissing sound from an area of the rim. That area didnt change regardless of many tries of reinstalling.
Last edited by: jakesdk: Sep 11, 19 5:16
FlashBazbo wrote:
The bike had been completely idle for only three weeks, but I had been out on it sporadically for maybe a month before that. About once a week I would spin the wheels in hopes of keeping the sealant doing its thing. Both tires were installed and topped up the same way at the same times -- the last top-up was about 9 weeks ago. When I opened them up, the front tire was completely dry and had the characteristic congealed solid "puddle" at the bottom of the tire. The rear tire had some light congealing at the bottom, but still had some liquid sealant. (Orange Seal Endurance) The inside of the rear was coated evenly, but had one "booger" where the sealant had sealed a puncture I was unaware of.

Thanks for the report. I'm wondering if this is an Orange Seal Endurance thing, because I can't recall any reports of other sealants doing this (but it could be a problem of sample size, too). Some seem to evaporate or congeal differently... Hutchinson sealant became like an evenly distributed (but mostly dry) tacky glue. I've had Bontrager TLR go bad and congeal in the bottles (later to learn that they have a 1-year recommended shelf life), but in my MTB tires it pretty much seemed to evaporate with no mess or puddles... and I didn't ride that bike very frequently. I've also run sealants in inner tubes quite a bit, so I can't see its condition unless I cut the tube open.
marting wrote:
What am I doing wrong?

I'm on my 4th (fourth!!) attempt to run a tubeless setup on my Cervelo S5, with Conti GP5000TL on Mavic Cosmic Elite UST wheels. The tyre inflates properly with little effort, seat properly and seem to seal around the rim. I can't hear any hissing, but the tyre deflates slowly overnight. This only happens with the rear wheel - the front sealed first time and has been problem free. And other tubeless wheels I own have been easy to set up. So hopefully I'm trying to do this correctly!

I've tried the originally installed Mavic tubeless rim tape, and 3 attempts with others. I've installed the tape and then left it overnight with an inner tube inside to help the tape adhesive bond to the rim.

I'm using the Mavic shaped valves which are designed specifically to match the centre channel on the rim.

I'm using 18mm tubeless specific rim tape which fits neatly into the rim. The rims have a specified 17mm internal width, but that's between the outer edges of the braking surface, not the tyre bed, which is slightly wider.

There's plenty of sealant in the tyre (40ml), and I'm shaking/bouncing/riding the tyre in every orientation to ensure it's available at all possible leaking points.

I *think* what's happening is that imperfections in the rim surface (there are a couple) make it impossible for the rim tape to stick properly, and the air/sealant just sneaks underneath at these points, leaking into the interior of the rim - there's no leaking sealant visible externally.

Any ideas for what else I could do?

Or should I simply return the wheel to the vendor, on the basis that it doesn't perform as advertised.

I haven't used any of the recent Mavic road UST stuff, but this is my best educated guess (having used a bunch of other tubeless stuff).

1. In general, I see a higher leak-down rate of tubeless tires compared to (butyl) inner tubes. So there's a little bit of this that's going to happen... but not as fast as you're experiencing.

2. When you say it deflates overnight - are the tire beads staying seated in place? As in, they're not coming undone and unlocking past the bead shelves? The reason I ask this is that I'm wondering if they aren't getting fully seated in the first place.

3. MTB UST stuff always worked best when you used a UST tire + UST rim. Things could get wonky when you deviated. For example, I had a UST gravel tire bead catastrophically fail during inflation on a Stan's rim (which are more intended to be used with tube-type tires converted to tubeless, or "tubeless-ready" tires). And I've definitely seen reports of non-UST MTB tires not seating or sealing as well on UST rims. UST was conceived as a system, whereas a lot of the tubeless-ready stuff is a little more 'wild west'. I've heard that their road UST tires and rims work really well when used together.

4. How tightly do those tires fit on those rims? It seems possible that they're too loose, and you may need to build up additional layers of tubeless tape.

5. Did you tighten down the valve stem a lot, and use an o-ring under the locknut on the inner side of the rim? Are you sure that the hole you cut in the tape for the valve stem hasn't grown, or that the tape hasn't split around this area? I've seen this result in leaks. My tubeless installation video shows the details of how I cut valve holes, and talks about tightening down the lock nut sufficiently.

6. What sealant are you using, and how old is it?

7. It's possible that your tape is leaking, as you mentioned. I've had the best luck with Stan's tape (and Hed, and Vision Tech, which seem to be identical). You can remove the tape, clean the rim with alcohol, let it dry, and install fresh tape (TIGHTLY), install inner tubes, and pump to max pressure overnight. This has always worked for me. Old-school tubular folks would lightly sand aluminum rim surfaces to roughen them up for better adhesion... though I'm sure this would void your warranty if you did it to your rims.
Greg, I thought all UST tubeless rims lacked spoke holes (mine all do). I thought part of the UST spec was a hole-less rim channel that requires no rim tape. Am I mistaken?
FlashBazbo wrote:
Greg, I thought all UST tubeless rims lacked spoke holes (mine all do). I thought part of the UST spec was a hole-less rim channel that requires no rim tape. Am I mistaken?

That's a good point. I know that was true at least in the MTB days. You didn't need tubeless tape when using UST tires... but sometimes you did need tape with "tubeless-ready" tires (non-UST), because they didn't always fit as well, so sometimes you have to build up the rim bed with tape.

And that could be what's going on here, too. The Conti 5000 isn't UST. I wouldn't see tape hurting the situation unless it made the tire/rim fit too tight, which could keep the tire beads from completely snapping up into place on the bead shelves.
Last edited by: gregk: Sep 13, 19 8:01
Have you tried putting the front tire on the rear to eliminate a possible tire issue variable?

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I want to run Tubeless this year for Kona, what tires rim tape and sealant would be best for typical Kona conditions?

I have ENVE 7.8 and have used Corsa Speed tires and latex tubes.... been lucky - no flat issues. Recently I have flatted in same setup with slow leak flats.... so figure I will try Tubeless. My first attempt installing G2 Corsa Speed I used Stans Tape and sealant. Tape had been on with tube before and the front leaked at spoke holes where tape became porous. I retapped with the 3M 8898 blue tape two layers... no problem now. Will redo rear tonight. I am also interested in the new Schwable Pro Ones. Maybe they are slower but better flat protection?
scca_ita wrote:
I want to run Tubeless this year for Kona, what tires rim tape and sealant would be best for typical Kona conditions?

I have ENVE 7.8 and have used Corsa Speed tires and latex tubes.... been lucky - no flat issues. Recently I have flatted in same setup with slow leak flats.... so figure I will try Tubeless. My first attempt installing G2 Corsa Speed I used Stans Tape and sealant. Tape had been on with tube before and the front leaked at spoke holes where tape became porous. I retapped with the 3M 8898 blue tape two layers... no problem now. Will redo rear tonight. I am also interested in the new Schwable Pro Ones. Maybe they are slower but better flat protection?

Unless somebody knows something I don't, there's nothing special about conditions in Kona that would change your tubeless setup or sealant choice. You generally want to avoid using more than one type of sealant in a wheel/tire (unless you clean the wheel and tire *thoroughly*... to avoid coagulation, or other problems when non-compatible sealants mix).

ENVE has their own tubeless tape (and valves), which is where I would personally start. They also have tubeless instructions here. I've never used that 3M tape, and have had the best luck in general with Stan's or similar. I avoid tapes that aren't specifically sold as being for tubeless bicycle tires, because things usually didn't go well in the old days using non-bicycle rim tape for inner tubes (i.e. electrical tape is a no-no).

I always make sure that the rim bed is totally clean and dry, and then I install tape with inner tubes and tires overnight to make sure it's stuck down. I also make sure to have enough overlap in the tape, as discussed in this video. If the tires fit too loose and are leaking down because of that, I'll re-do the tape with additional layers as needed.

I haven't used the newest Pro Ones (I'm on the pre-2020 model now), nor the Corsa Speed, but every report I've seen suggests that the Corsa Speeds are very flat prone i.e. more than the Schwalbes.
Last edited by: gregk: Sep 24, 19 9:48
thanks Greg, are we at a point where a tire being more flat prone is now mitigated by sealant ie Pro One and Corsa Speed are now equivalent flat protection.... as opposed to using a inner tube? My assumption is sealant will Seal most punctures
Specifications for non-proprietary tubeless rim tapes would be a really useful contribution to this forum. The wheel manufacturersâ€™ branded tapes are ~10x the price of the 3M product mentioned above, and Iâ€™d speculate thereâ€™s nothing particularly special about them.

So, does anyone know what these rim tapes are made from, and how thick the material is?
scca_ita wrote:
thanks Greg, are we at a point where a tire being more flat prone is now mitigated by sealant ie Pro One and Corsa Speed are now equivalent flat protection.... as opposed to using a inner tube? My assumption is sealant will Seal most punctures

In my experience, we are not there, and unless something dramatic changes with sealant or tire technology, it's not something that will happen. I wrote about it here (and probably elsewhere).

Specifically: "That said, just because you have tubeless tires and sealant does not mean that youâ€™re immune to flat tires. In fact, many of the new tubeless road tires are being made thinner and thinner on a quest for faster rolling resistance numbers. Translation: some tubeless tires, despite having sealant, are more fragile than the regular clincher tire/tube setups. Sealant canâ€™t fix large cuts, and thin casings donâ€™t hold their shape very well (which makes sealants less effective). It seems there is no free lunch to be had when it comes to sealants."

Say you have an object on the road that is large and sharp enough to puncture a tread that's 2mm thick, but not one that's 3mm thick. Of course, I'm ignoring puncture breaker materials for the sake of this example, which won't necessarily all function the same. If you hit that object on the thinner tire, you puncture, and the sealant has to seal the hole - which isn't a guarantee. On the thicker tire, it just rolls over the object, doesn't puncture, and you keep riding.

This applies to both tubeless and inner tubes. Beefier tires are just less flat prone, period. That doesn't mean that they'll avoid all flats, or that there aren't applications for thinner and faster tires. It means that there's a place for all of these products, and it's up to the user to pick the best one for their needs and risk tolerance. Also, sealants have improved a decent amount over the last 15 years or so, but it'll take a big leap to really change the situation.
marting wrote:
Specifications for non-proprietary tubeless rim tapes would be a really useful contribution to this forum. The wheel manufacturersâ€™ branded tapes are ~10x the price of the 3M product mentioned above, and Iâ€™d speculate thereâ€™s nothing particularly special about them.

So, does anyone know what these rim tapes are made from, and how thick the material is?