How to prevent punctures once and for all!

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Re: How to prevent punctures once and for all!

Postby thunderstorm80 » Sun Sep 24, 2017 3:39 am

DRMousseau wrote:
thunderstorm80 wrote:Wait... So according to the stick-to-the-max-pressure approach, I understand that having a fat-Ebike with Surly blackfloyd's (2 6 x 3 . 8 ) so I can run them at 15PSI or lower is a very, very bad idea on roads?
I have built that E-bike so I can carry luggage around town and when going long distances like traveling - The super wide tires are cushioning your entire bike mass including the panniers - something which cannot be achieved with a regular bike. (Full suspension bikes can only have seat-post rack as it's their only sprung-weight storage space)
Their absolute max pressure is 30PSI but I plan to use them at 15PSI on good roads, and 8-9PSI on roads which are badly maintained.
So I understand that with that huge contact area, especially at the lower pressures, I should carry lots of spare tubes, hole-plugs (worms), seal-in-a-can, etc?
I thought before starting this thread that the super low pressure on the fat-tire will make glass and other sharp objects less prone to interfering with the tire - just like if you roll a beach ball on shred-glass vs sitting on the ball (increased pressure) while doing so.


Actually, the preconceived notion is that of two balloons being pressed on sharp objects,.... one being grossly underinflated, the other being inflated to max capacity. The underinflated one will likely survive much better IF, it can stretch and shape about the object without damage. And the same is true of bicycle tubes,... which is why these tubes are in protective tires!

THE PRIMARY PURPOSE of tires, is to provide an easily and economically repairable or replaceable bearing surface that is subject to wear and tear, while providing "shock" absorbing protection to the supporting wheel assembly and axle. Jus last night, I luckily repaired a damaged rim for the grandson's BMX,... the result of an underinflated tire that failed to fully resist the "shock" at a point of impact, that crushed the tire and tube, transferring the remaining energy into a point on the rim edge, and folding it over a bit. We were both surprised that it was reasonably repairable with serviceable satisfaction. While tire and tube were replaced, the possible cost of replacement to rim, wheel assembly, and/or the labor of re-lacing and such, instilled a sense of value in my grandson of the importance of proper tire inflation and closer regular inspection!

So is 15PSI or lower is a very, very bad idea on roads? No,.... unless other considerations of expected road surface, hazards, load, etc., suggest otherwise. Surly outright recommends the lowest listed inflation of manufactures suggested pressure range, with max rated pressure only to seat tires to the bead. That lowest keeps within the tire manufactures specs (liability protection),.. the minimum to maintain bead on SPEC RIMS at minimum expected loads, speeds, surfaces, etc., while providing maximum bicycle "product" protection(?) of major components (warranty protection). Will that pressure protect your rim against an unexpected pothole with a heavy load, or your axle and bearings against a high-speed curb smash??? Probably not, and nether will the warranty,... "typical" or "normal" use clause, ya know?! And tires are usually excepted with some exclusions too. But if your "normal", stay within Surly's guidelines, their warranty is protected!!! Now your low-pressured tires will be subject to a lot flexing and wear, internally and externally, and a shorter life,... but well within the tire manufactures warranty as well!!! And THAT'S what's most important to manufactures! But that doesn't protect YOUR investment and costs! And those Blackfloyd's aren't cheap tires!!! Nether are Surly rims!

Max psi of suggest tire pressure ranges is well within the limits of typical rim specs, unless brake surfaces are badly worn. It's also well within the limits of safety for expected maximum bike loads, temperature expectations, and speeds. "Fatter", bigger tires generally need less psi to meet those specs,... smaller, thin, "skinny" tires generally need a higher pressure range to maintain the safety needs expected.

Your choice of bigger "super wide" tires for cargo loads, is more a choice of "weight capacity". Bigger tires are capable of a greater weight load at a given inflation pressure than smaller tires at the same pressure and weight load, providing greater "shock" protection. So what's the lower limit??? eh? Should ya carry all that tube, tire and stuff for flats??? mmmm,.... should ya carry an extra rim or wheel assembly??? eh? I don't,... I jus keep my tires well inflated and stay hopeful, lol. No real problems yet.

My current road build under construction is designed with EXTREMELY heavy rear end load capability (hub motor, battery, adult rider AND adult passenger, plus extras? with mostly rear bias) ,... like max load in the near 400lb range on rear tire alone!!! I have many unique concerns here. No bicycle tire is truly capable of such loads and still provide the safety and protection needed as an e-bike. I also have unique considerations of rim choices, spokes (number, length, AND ga.), axle loads (length and dia), frame and dropouts, and jus SO much more! My choice of "super wide" tire has fallen into a 150/80x16" on a double-walled 20"x100 rim,... outside tire dia., is 26". Max rated pressure is 40psi@900lbs,.... I'll likely run about 20-30psi depending on MY load and what keeps the tire in a full profile for min rolling resistance. The heavy 5/16" tread alone (yup,.. run tubeless) should keep me pretty much "flatless"!!! LOL!!!

Regardless of the recommended pressure, most bicycle tires won't hold up to slashes and cuts very well, although some specialties DO have a special layer within, jus for such expected and often encountered incidents. Designed to limit the spread of cuts and tears and still maintain internal construction integrity.

And them dang "goat-heads", burs, thorns, spines and such,.... a heavy thick tread and tire surface is best! Anything else is jus "hopeful".


You quoted me, wrote so much but you didn't relate to what you quoted from me. :D
So here it is again: I want to know about the relation between the contact patch, the pressure and the width when talking about a Fat-Bike tire.
I assume there are a bit different considerations than regular tires. (Just like most fat-tires are squirming at their standard pressure while standard tires don't)
I want to know if it's more probable to get a flat on the road from a fat-tire (2 6 x 3 . 8inch ) at 10-15PSI, compared with a standard 29x2.1inch tire at 40PSI. (assuming both tires have the same tread pattern, same construction, same puncture resistant features, etc...)
Last edited by thunderstorm80 on Sun Sep 24, 2017 8:48 am, edited 1 time in total. View post history.
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Re: How to prevent punctures once and for all!

Postby markz » Sun Sep 24, 2017 2:03 pm

When you think of an offroad tire on a truck/suv of the same exact tire and on road you inflate to regular pressure, say 35-40psi. Then you run the exact same tire at very low psi for snow and ice.

Low psi = larger contact patch
That is the whole reason for "airing down"

What you are then stating 26" x 4" with low psi compared to 29" x 2" with high psi (for simplistic I've rounded your numbers)

So two different diameters of tire, and one is 2" wider.

My initial gut reaction would be the low psi 26'er is not good at all, I'd say there is a very huge contact patch compared to the high psi 29'er.

The only way to confirm is a real world test. Dip wheel in water, and put total weight on it and see the contact patch.
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Re: How to prevent punctures once and for all!

Postby DRMousseau » Sun Sep 24, 2017 10:32 pm

thunderstorm80 wrote:I want to know if it's more probable to get a flat on the road from a fat-tire (2 6 x 3 . 8inch ) at 10-15PSI, compared with a standard 29x2.1inch tire at 40PSI. (assuming both tires have the same tread pattern, same construction, same puncture resistant features, etc...)


YES,.... it's more probable that ANY low pressured tire will receive more punctures and other damage, given same construction, loads, and conditions. How much more, depends on how much greater the lower pressured tire deforms under load. If neither, low nor high, deform under a load, then the difference is minimal. If ANY tire deforms greatly, regardless of pressure, it will be more subject to punctures and construction damage.

To compare the two tire examples you noted above, will still rely primarily on that deformation factor. The low pressured "fat" tire MAY have more load capacity at that pressure then the standard does at a typical pressure, and may resist deformation with the same given load, and again, the difference in damage resistance may be minimal. If ANY tire deforms under a given load,... it is more subject to damage.

The "contact patch" MAY be very different between your two examples. Given no deformation of load between them, the 26" "fat" tire will have short broad contact, while the typical 29" tire will have a longer more narrow patch,.... the obvious differences of width and dia.,... although BOTH may have identical contact "area". If so, the longer contact will usually have a "smoother" ride over the same given surface, and may encounter less "objects", given it narrowness, in direction of travel. Given the same "contact area", both tires will also likely have similar rolling resistance.

Your choice in a in a wider tire for carrying heavier loads is great,.... but all the advantages may be lost in excessively low inflation.

markz wrote:When you think of an offroad tire on a truck/suv of the same exact tire and on road you inflate to regular pressure, say 35-40psi. Then you run the exact same tire at very low psi for snow and ice.

Low psi = larger contact patch
That is the whole reason for "airing down"

What you are then stating 26" x 4" with low psi compared to 29" x 2" with high psi (for simplistic I've rounded your numbers)

So two different diameters of tire, and one is 2" wider.

My initial gut reaction would be the low psi 26'er is not good at all, I'd say there is a very huge contact patch compared to the high psi 29'er.

The only way to confirm is a real world test. Dip wheel in water, and put total weight on it and see the contact patch.


"Airing down" for larger contact patch provides more surface contact for traction in soft or loose surfaces. It also provides more "grip" on firm or solid surfaces,.... at the expense of rolling resistance, tread wear, handling differences, and damage risks of course. But your "initial gut reaction" MAY be inaccurate. A wider tire may not necessarily mean a significantly wider point of tread contact on a solid surface, but will give a broader yet shallow tread contact on soft or loose surfaces. This gives "fat tire" the advantage of low rolling resistance on the road to the beach, where their greater width rolls 'em over the sand so nicely,.. and without a change in inflation pressure! "Airing down" a 2" tire to get a 4" width might get ya over the sand ok,... handling will be hell, and the rolling resistance on the road will be worse than hell! lol!

"Airing down" is never good at all,... it's a "make do with what ya got" kinda thing given the circumstance presented. Best to have a tire for the purposes AND LOADS intended. A "dual-purpose" or "multi-purpose" tire is general and not really specialized for a specific purpose, so there may be some disadvantages with advantages,.... snow tires vs. all weather tires vs standard road tires,... the same is true of bicycle tires.
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Re: How to prevent punctures once and for all!

Postby bowers » Fri Sep 29, 2017 6:00 am

I'll throw in my experience here...

27,5" / 2.1 wheels on a MTB with a 4kw rear hub DD motor. I usually ride on streets and forest trails (20-50 km/h)
I started off with around 40 PSI which felt good and gave good contact in trails etc.

The first 2000 km of riding gave me 4-5 punctures, all of them "pinch punctures" from hitting shit in high speeds.

I then increased pressure to 65-70 PSI which is max pressure for my tires. I've done around 4000 km after this and with the exception of 1 puncture from a large spike (which nothing can withstand), I've had no punctures since this.
The higher pressure makes the bike a little more nervous on gravel etc, but on streets it feels perfect.

So in my experience... More pressure is always better to avoid punctures (Until you reach the limit)
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Re: How to prevent punctures once and for all!

Postby csc » Sat Sep 30, 2017 8:21 am

Same advice as ions82 and Dogman dan : if you can't put a motorcycle rim/tire, check the bike tire inside of another tire.

Here's what I do with my rear wheel (front is made of motorcycle parts, I'll do the same on the rear later) : I put a very used slick Marathon almotion 26 x 2.15 inside of a 26 x 2.50 Hookworm without cutting anything (rim is an andra 40 around 35mm wide). Then inflate to 4.5 bars.

It's now been more than two thousand kilometers, often over 100 km/h : no puncture nor tire moving in an unappropriate position.

I also made a 400 km trip with my girlfriend as a passenger and a trailer. So far so good. Might also keep it as is.
Last edited by csc on Sat Sep 30, 2017 8:29 am, edited 1 time in total. View post history.
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Re: How to prevent punctures once and for all!

Postby DRMousseau » Sat Sep 30, 2017 10:24 am

csc wrote:Same advice as ions82 and Dogman dan : if you can't put a motorcycle rim/tire, check the bike tire inside of another tire.

Here's what I do with my rear wheel (front is made of motorcycle parts, I'll do the same on the rear later) : I put a very used slick Marathon almotion 26 x 2.15 inside of a 26 x 2.50 Hookworm without cutting anything (rim is an andra 40 around 35mm wide). Then inflate to 4.5 bars.

It's now been more than two thousand kilometers, often over 100 km/h : no puncture nor tire moving in an unappropriate position.

WoW! :shock:
Now THAT'S a tough "combo"!!! And HEAVY duty!!

The Almotion seems a great e-bike tire in itself,... and when "worn out", this is a good way to get "extra" use of it, inside the tough rim-to-rim tread and construction of the Hookworm. Something that may likely survive a nasty slash, and still get ya around!

Everything about this says, "It shouldn't work or last long",.... and it probably wouldn't, save one little secret here,...
csc wrote:Then inflate to 4.5 bars.

That's about max inflation pressure for the Hookworm,... keeps everything pretty solid and in place inside, and keeps any deformation and flexing to a minimum, so there's no pinching, no internal rubbing and such. At high speed, you can be sure of heat problems,... but that means extended road time in excess of 80kph/50mph!!!! But what a tough setup among the rocky trails!!!
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Re: How to prevent punctures once and for all!

Postby csc » Sat Sep 30, 2017 10:51 am

DRMousseau wrote: At high speed, you can be sure of heat problems,... but that means extended road time in excess of 80kph/50mph


Well I was fearing that, but as nothing exploded after several 30 km sessions on the highway, with a constant 110km/h, I'm more confident now.

It's still supposed to be a temporary solution before motorcycle parts, but the trick can be permanent for those who have no space for moto tires. Let's say under 80km/h.
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Re: How to prevent punctures once and for all!

Postby ScooterMan101 » Sun Oct 01, 2017 12:08 am

thunderstorm80,

Try the Continental Tour Ride tires, I have a set on my Mac motor MTB, riding only on roads,
1400 miles now and only one flat , it was the biggest Goat Head Thorn I have ever seen in all my years of
goat head punctures.

I now also put stans no tubes sealant in my tubes as well, Specialized Tubes / and some Continental Tubes have a removable valve core , on their presta tubes.

They come in 27.5 ( 650b ) versions that are 42mm wide or 54 mm wide, I have the 54 mm ( 2.1 inch ) wide ones.

http://nextday.bike/details.aspx/010010 ... ide-21/517
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Re: How to prevent punctures once and for all!

Postby markz » Mon Oct 02, 2017 2:48 pm

Alright Chalo, I've read your posts so I am buying Schwalbe Marathon Plus because Chain Reaction Cycle sells them for $32, plus its rating of 6 (the most protected tire) on their website.
https://www.schwalbetires.com/bike_tire ... n_plus_mtb

I see the Panaracer RiBMo is your preferred tire for comfort and it comes in 26" its about $50cad shipped on ebay
https://www.panaracer.com/comparison/

I have two ebikes, one is my daily rider; a Townie 21D 3x7 (Front Susp) currently has the Cyclone 4k mid drive which I have to change the gearing and see how far I can go compared to my 1kw dd. I did a relaxing single track trail run in the woods on this exact setup and it was really peaceful and serene. My first off road experience.

My other ebike is a department store Full Susp frame with the frame holding the battery from headset down to bb. Its a more upright stance, and needs fixing due to the rear shock mount breaking from my 388lb butt. Needs a layback seat post but I may weld my own soon enough as I dont like the height that is required on the layback seat posts.

There was a time when I went through tubes like crazy because of spokes and the weakened rim. Cant do nothing about it except build rim properly. But I'm going the extra mile for protection and on my 2nd ebike, going to be rocking moto rims/tubes/tires with a high powered dd motor. But my Townie will be doing Schwalbe.
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