Fat Tire Bikes
 

Greetings,

I work as a mechanic at a bike shop in New Mexico that does e bike rentals. The rains this year produced quite a lot of goat heads, and the bikes were always coming back flat. I had the owner order 1/4 inch thick by 4 inch width rubber from amazon, and installed it into the tire between the tube and tire. Most fat tire bikes are inflated to 30 psi, I ramped this down to 25 psi to account for the rubber thickness. The tires seem to be holding steady with no flats. Most tire liners are super thin, but thought hey, lets go the opposite direction, and increased liner thickness. It will add weight of course but since these are e bikes, its not really noticeable to the customer. It is possible to decrease the thickness to an 1/8 but have not gotten that far. If you are tired of changing out e bike flats this might be worth looking into.

Cheers!

I think we might have a communication issue: if you are really running fat bike tires at 25-30 psi, you have got them inflated 2x (or more) higher than most people would run on the smoothest pavement.

Or are you actually referring to wider tires on mountain bikes?

Anyway, interesting idea on the rubber liner. I suppose the liner, along with the tire itself, creates a thick enough barrier that the goatheads can't penetrate through to the tube. Are you finding thorns stuck in the tires when people bring back the bikes?

I would look at good tires and Tannus Armour. However like Koyote said if you are talking Fat Bikes like say this you are running really high pressure some fat bike races people are running 3 PSI on pavement probably no more than 20 and more than likely probably a 10-15psi.

I had to intervene at our local bike coop when a customer and volunteer read "72 TPI" on the tire and were trying to inflate them to 72 PSI. That might have blown the windows out of the building. 30 PSI is pretty extreme for 4" tires.

Greetings,

Apologies for the confusion, the tires are on an NCM Aspen plus, 26 x 4.0, inflate to 30 psi on the sidewall. CST Big Boat Tires. I do understand you can run them at lower pressures. TPI (threads per inch), I run the Vittoria Corsa tires on my time machine with 320 tpi, keep them at 115 psi. And Yes, the tires come back packed with thorns.

Cheers!

Lower that pressure a lot. 30 PSI is the max on those tires more than likely. The Tannus inserts I recommended are also a good idea but that pressure is way high.

a lower tire pressure allows the tire to conform over a thorn, Compressing the rubber at the tip of the thorn and reducing the puncture rate and depth.... :thumb:

not a total preventative action, but it does help......

30psi is MUCH too high for a 4" wide tire. The label on the tire is indicating the MAXIMUM pressure, not the ideal pressure. I run about 10psi in my fat bike tires in the summer, lower in the winter for snow. If I were riding on the road only I might go up to 15 psi. 30 psi is insane and pretty much completely negates the advantages of having big fat tires. Soft tires are the whole reason for fat bikes - allows flotation on soft surfaces and absorbs small obstacles and irregularities - and soft tires will, as mentioned above, be less prone to punctures.
The only drawback to having low pressure is the tires will roll more slowly or take more effort to roll at your desired speed, but with an E-bike this is not an issue. For the love of your clients, PLEASE run those tires at lower pressure.

Actually not true. 30 PSI on a fat bike tire will turn the bike into a bucking bronco. Any gains in rolling resistance due to hysteresis will be more than negated by tremendous suspension losses. You will actually be slower, not to mention the ride will be miserable.

Again as others have said, 30 PSI is WAAAAAAAAAAY too much pressure in a fat bike tire. Keep in mind that the PSI listed on the side of the tire is the maximum the tire will safely accept. It is not a recommended pressure. 10 PSI is closer to the optimal pressure for these tires, even less if you are off-pavement. In fact, the ski centers that rent out fat bikes for the ski trails keep their fat bikes at around 6 PSI because more than that will rut the trails.

I will also chime in that 30psi is ridiculously high for 4" tires.

My Surly Krampus wears 3" wide tires, I'm a fatso at 250lb, and I consider 10 psi front / 15 psi rear to be pumping them up extra high. 8/12 is probably ideal.

Get the fattest person you can find and have them bounce up a standard sidewalk curb. Lower the pressure gradually and repeat. When they finally touch the rim, add a few psi back and use that.

Yes, but within the acceptable range of fat bike tire pressures, say, 4 to 15 psi, dropping from the high range, which might only be acceptable for riding on smooth/paved surfaces, to the lower range that's best for very soft surfaces or snow, there is a remarkable decrease in speed for a given power output by the rider. Yes, 30psi will be slower and unacceptable for multiple reasons, but dropping from 12psi to 5 psi will absolutely make you slower on hard surfaces, although it also makes it possible to ride on terrain you can't at 12psi.

Agreed. I was merely disputing your implication that 30 PSI (when you said low pressures would make you slower) would make you faster than something in the correct range of pressures. I apologize if that isn't what you meant.

Lombard I've never tried it, but I'd be interested to see if it isn't true also when riding with grossly overinflated 30psi tires, if riding on glassy smooth pavement. Unfortunately, I don't think the Gorilla Tape I use for rim tape would hold up to such an experiment.

I suspect, as long as the tires are rolling round enough, 30psi would actually roll pretty fast until you hit a pebble or a cigarette butt and got bucked off the bike.

Maybe ebike specific tires have street tread, but no matter how smooth the road, MTB fat tires with knobby tread would still be a rough ride

Maybe on a glass velodrome. On normal pavement, no, the asphalt surface itself would be enough to give you suspension losses at 30 PSI.

I have a fat e-bike with 26 X 4 tires and tubes and I have used Orange Endurance Sealant successfully to reduce flats caused by the many thorns I encounter on single track in the woods but I’m not sure if it would be as effective against goatheads. I generally run tire pressure around 9 psi off road and closer to 12 psi on smooth roads.

That sounds like a cost effective way to reduce flats, surely less expensive than a bike specific tire liner product like Toughies. Have you tried running them with sealant instead of a liner?

Appreciate all the good information! Thanks!

Albuquerque is pretty much ground zero for goat heads lol, We have tried just about everything, Slime, stans, Mr tuffy liners, tannus armor. This rubber strip I selected is 1/4 inch thick and 4 inches wide, comes in 20 foot rolls for about 60 bucks. It molded very nicely inside between the tube and the tire. The ride was smooth. The project is still in the works, but so far so good. For example, a flat repair on an ebike cost 25 for the tube, and like 25 labor, slime is extra 5 bucks. The rubber strip if it turns out to work would save a lot of repair cost. Will keep ya all posted!

Cheers!

This is the search criteria for the Rubber:

Neoprene Rubber Strip.250" (1/4") Thick x 4" Wide x 20' Long - Commercial Grade 65A, Smooth Finish, Solid Rubber

If you want an idea of the flat issues, look up goat heads vs bike tires in New Mexico, then look at images.

30 psi in smooth fat bike tires like VoodooSix is using doesn't ride all that poorly. In fact, it helps tremendously with self-steer. I have a pair of Vee Speedsters (26x3.5) that I sometimes run on a Pugsley and anything less than about 20 psi creates so much self-steer, the bike is almost unrideable. 10-15 psi means you're truly fighting against the handlebar in a turn. They really smooth out at about 23-25 psi. Because it's a steel frame Surly, there's definitely some suspension in the frame and the ride is not unpleasant. The higher pressures make it possible to ride the bike with those tires.

The Speedsters have an inflation range of 8-30 psi, so their minimum is higher than some would ever inflate a snow tire or a knobby on a fatty. I think it's really all about putting the right amount of air in a specific tire with a specific purpose in mind. Blanket statements rarely work for every situation.

https://cimg5.ibsrv.net/gimg/bikefor...40b5e93160.jpg

https://cimg6.ibsrv.net/gimg/bikefor...062c855c6d.jpg

Probably because those tires are more plus bike tires than fat bike tires which I think of as between 4 and 5 inches.

Ultimately, trying to find a happy medium with the 1/4 inch of added rubber. The inflation has to be enough to keep the 1/4 inch rubber in place rather than it wrapping around the tube as does the Mr Tuffy liners do. Was thinking about vulcanizing the rubber to the tire, but added cost. I sure appreciate the input all, it's a mechanics job to find solutions. People treat these rentals in bad ways, just don't want them having to push the rentals home. It's our job to give them a good experience despite them wanting to run intentionally through the goat head patches.

Cheers!!

Don't know if you've ever ridden a motorcycle, but you never try to fight the handlebar in a turn. You countersteer to get the bike to lean into the turn on its own. This is increasingly important as the bike and the wheels get bigger and heavier.

Interesting report, thanks. I sometimes think about buying a second wheelset for my Krampus with street tires, and living the minimalist life with just ONE bike :eek:

We will ostracize you here if you do that. ;)

n minus one!!!