I managed to scoop up a 27.5 inch mountain bike wheel on the fleabay in 110 boost spacing so I mounted a spare VeeTire co Crown Gem 2.8 inch wide tire. After MUCH frustration and an ungodly amount of muc-off sealant (180 ml!) I finally got the tire to hold air.

I figured a nice big front tire would add a bit more plush to the “firm” riding oversized chromoly tube hardtail. It did but overall it wasn’t worth it. The wheel is noticeably heavier, harder to pedal on long distances and it manages to fling tons of small rocks, dirt and crap up at me when I ride.

I think it might have been a combo of bone dry trails and a new tire but this new tire seems to really fling up a lot more crap than my old tire.

After just one ride I swapped it back to the 2.6 inch tire.

Do you think the different tread pattern was the reason a considerable amount of crap was getting tossed up by my 2.8 tire? Was it also because it hasn’t rained in a month and the trails are crazy dry?

Look at the size difference! Old tire is under the new tire/wheel which was mounted when I took the pic.




I’m still not 100% sold on the beefy as hell Chromag stem and Deity 35mm bars with a 50mm rise. It feels a lot more like my old BMX bikes and dirt jumpers but the cornering has really suffered with the high bars.

I have been wondering about the continually-increasing sizes of mountain bike tires for some time. Around here they have become more obvious in the past few years. It was first because cyclists were more commonly riding year-round, with a lot of use in the snow. A really fit friend rides his bike in the winter. I see sizes that would seem more at home on motorcycles than bikes. More and more, though, the really fat tires aren’t being changed to narrower sizes in the summer, and that’s what puzzled me. Long, long ago it was conventional wisdom that if the riding surface made it possible, the narrower the tire, the less rolling friction and therefore the less effort to pedal. I suppose that if someone is just looking for resistance that really fat tires make sense, but otherwise—?

Except friction is independent of surface area

sigfreund,

I suppose it depends on the bike and whether the rider has gotten used to the tires. This Marin Pine Mountain doesn’t have a front suspension fork so the 2.8 inch tires (exact same as the one I recently installed) really help improve the ride by adding a bit of cushion. The tires are set up tubeless and a bit low on the psi for maximum give without risking the rim.

I get the snow riding thing. The plus size tires worked pretty darn good. It’s my bad weather bike and now has front and rear fenders that were added after these pics were taken.




I have not ridden a “fat tire” bike but some of them have silly looking tires that look like they were taken off a dirt bike. I want to ride one soon.

Thanks for the explanation.
The cushioning advantage is understandable.

quote:

Originally posted by stickman428:
I managed to scoop up a 27.5 inch mountain bike wheel on the fleabay in 110 boost spacing so I mounted a spare VeeTire co Crown Gem 2.8 inch wide tire. After MUCH frustration and an ungodly amount of muc-off sealant (180 ml!) I finally got the tire to hold air.

I figured a nice big front tire would add a bit more plush to the “firm” riding oversized chromoly tube hardtail. It did but overall it wasn’t worth it. The wheel is noticeably heavier, harder to pedal on long distances and it manages to fling tons of small rocks, dirt and crap up at me when I ride.

I think it might have been a combo of bone dry trails and a new tire but this new tire seems to really fling up a lot more crap than my old tire.

After just one ride I swapped it back to the 2.6 inch tire.

Do you think the different tread pattern was the reason a considerable amount of crap was getting tossed up by my 2.8 tire? Was it also because it hasn’t rained in a month and the trails are crazy dry?

Some tires are better than others at sealing up/setting their bead on a tubeless wheel. I've never used Vee but the issue with sealing up (and holding air?) could just be down to a bad bead on the tire or a small leak in the rim tape or your wheels internal width isn't wide enough to support the 2.8.

Fat tires aren't a cure all for harshness on the trail, especially on a rigid bike. After years and years of riding I've found that tire pressure and wheel compliance are going to be the determining factors in how much fun you have on any given day. I've never put more than 20 psi in a tire larger than a 2.6. In a 2.8 i would go much lower depending on feel.

Experiment with tire pressure before changing anything else and dial it in from there. Also remember that tire compliance is no substitute for actual suspension, even 80-100mm makes a HUGE difference in feel and handling.

Re kicking up rocks, my Epic kicked rocks into my shins with every tire I ever tried on it except Specialized Fast Track so that's all I ever rode on. Getting my shins kicked in by fist-sized rocks got OLD after a while.

quote:

Originally posted by Dakor:
Except friction is independent of surface area

It’s more complicated than that.

Larger bike tires are run at lower pressures. Larger tires deform more as the wheel rolls. This is a major component of rolling resistance.

If “friction is independent of surface area” is the whole answer, why does your car get worse MPG if the tires are a little flat? Why do road bikes use super skinny tires at 100+ PSI?

I always did it the other way; 65 to 110 pounds of pressure in super skinny tires, with a very tiny center bead. Rolling resistance little to none. (Road bike)

Keep that rotational mass down! lol

Besides the comfort advantage, larger tires run at very low pressures are supposed to provide a big traction advantage on bumpy/rocky trails. When there are rocks that are too big for the tread to grab, the tire can kind of just slide across the bump. Letting the tire “squish” around the bump gives it a lot more grip.

The result of this is that the majority of people who ride aggressively on rocky trails use tubeless tires with tire inserts (foam rings that go around the wheel inside the tire to protect the wheel from impacts and help keep the tire bead from folding in and popping off the rim).

This lets them run MUCH lower pressures. With a tubed tire you’d get “snakebite” punctures in the tube (where squishing the tube between the tire and the rim when you hit a big bump punches two holes in the tube). With a tubeless tire you’d fold the tire in at the rim and unseat the bead. Both ways you’d risk denting the rim.

quote:

Originally posted by shigawire:


Some tires are better than others at sealing up/setting their bead on a tubeless wheel. I've never used Vee but the issue with sealing up (and holding air?) could just be down to a bad bead on the tire or a small leak in the rim tape or your wheels internal width isn't wide enough to support the 2.8.

Fat tires aren't a cure all for harshness on the trail, especially on a rigid bike. After years and years of riding I've found that tire pressure and wheel compliance are going to be the determining factors in how much fun you have on any given day. I've never put more than 20 psi in a tire larger than a 2.6. In a 2.8 i would go much lower depending on feel.

Experiment with tire pressure before changing anything else and dial it in from there. Also remember that tire compliance is no substitute for actual suspension, even 80-100mm makes a HUGE difference in feel and handling.

Re kicking up rocks, my Epic kicked rocks into my shins with every tire I ever tried on it except Specialized Fast Track so that's all I ever rode on. Getting my shins kicked in by fist-sized rocks got OLD after a while.

The leaking problem wasn’t because the rim was too narrow or not designed for a plus size tire it’s a 584x40 rim so it’s basically built specifically for tires like the 2.8 inch wide that I mounted.





I am fairly sure the leaking issue was because it didn’t have enough sealant. Once I finally got it to the correct amount I saw a little sealant leak around the bead of the rim and quickly stop the leaks.

My plan is to find a decent 120-140mm front suspension fork with 110 boost spacing and use this spare wheel on my green Marin Pine Mountain. That rigid fork is neat but there are days when I’d love for it to have a front suspension fork.

My opinion the new bigger tire has a slightly more aggressive looking tread that also looks a little deeper which could be contributing to more of the flinging that you are experiencing. God Bless !!!

quote:

Originally posted by stickman428:
I am fairly sure the leaking issue was because it didn’t have enough sealant. Once I finally got it to the correct amount I saw a little sealant leak around the bead of the rim and quickly stop the leaks.

My plan is to find a decent 120-140mm front suspension fork with 110 boost spacing and use this spare wheel on my green Marin Pine Mountain. That rigid fork is neat but there are days when I’d love for it to have a front suspension fork.

Good to know. I haven't ever personally owned a fat tire bike, but I've ridden MTB's since right after they matured from single speed clunkers....and worked on/set up a few owned by friends. I the closest I've come to a buying a fat/mid fat was a demo on a Pivot LES with a 2.8 front and 2.6 rear which was probably the most fun I've ever had on a hardtail...and I've owned more than a few. The carbon frame was as stiff a MTB frame as i've ever ridden but the tires and front 120mm fork made it into something between XC and Trail bike. Just brilliant all 'rounder with only a little bit of...bounciness in the rear.

In any case, good luck with your bike and setup. Play with the pressure till you get it just right and I'm sure you'll get it where you want it to be, it's a nice looking ride.

I’m starting to think even the 2.6 inch wide tires might need to go too.

I’d been riding my hardtail exclusively for a month or so. Today I took my full suspension Cross Country Giant Anthem MTB for a 10 mile ride. This bike has a 2.3 inch wide front tire and 2.2 inch wide rear tire. The Giant also has 29 inch tires front and back. Holy smokes the short travel Giant feels like a rocket ship compared to my heavy, overbuilt Chromag hardtail.

I was shocked by how much faster I was on the Giant when riding the exact same trails I’d been riding my hardtail. The 100mm front and rear suspension really soaked up hits from roots and rocks that would have caused me hell on my hardtail and made me slow down.

I understand the suspension plays a HUGE factor but even when just pedaling on the road to the park the smaller tires really felt a hell of a lot faster. I noticed a considerable difference in effort to maintain a decent cruising speed between the two bikes.

I’m now considering 2.2-2.4 inch wide tires for my hardtail.

This thing. (Seat was lowered because I was on a section of trail with lots of jumps)


Makes this thing feel like a rocket ship on the trails.

I have 27.5 x 2.25 Trail Boss tires on my gravel bike. They are the smallest I could fit with the Tannus inserts. Soo, hard to get on. They're not coming off anytime soon.