Fat, Cushy, Grippy EMTB Plus Tires

[The duke]

I recently purchased a BH Atom X that came with 2.8" x 27.5 plus tires (Nobby nics). I used to mountain bike in the 1990's with 'standard' MTB tires on a hardtail. The fat plus tires are amazing! I've got the pressure low (20psi). The grip blows me away....so much better than standard 2.25" tires. I cling to slanted trails & roots. I climb up things I couldnt walk up and braking is so strong! It also soaks up the bumps on my hardtail....it almost feels like I've got suspension.

Since I've got a motor, making rolling resistance less of an issue, I'm wondering how fat EMTB plus bike riders go with their tires? What's available and if I keep going fatter, will my grip keep getting better and will my ride keep getting cushier? I'm thinking 3.25" if I can find it. Anyone with any experience? Are there any drawbacks?

Also, when on the road, how tight do you guys turn on plus tires? How far can I lean it over? Grip on road feels insanely sticky but I'm scared I'll push it too far and have the bike slip out from under me!

 

[JRA]

In the early days of plus tires becoming available Vee made a 3.25 called the Trax Fatty. Probably still available but you might want to check your clearance for a wider tire especially in the rear triangle. I personally don't like too wide a tire on the front as it seems to affect steering as I am used to but in the back it makes good sense to use a higher volume tire.

Having a wide enough rim with a plus tire is as important as the tire width on the label. I feel an inner width of 35mm to be about perfect and can really make a 2.8, which it seems has become the go to size for the industry over wider 3.0+, can make a big difference on how the tire will perform and what psi you can run it at, especially in regards to absorption and traction.

It's good to be cautious of mtb type tires on the road as they can be unpredictable. There are models that will do well on both but usually they have less aggressive outer knobs.

 

[Dmitri]

Anyone with any experience? Are there any drawbacks?

I run no less than 3.8" on the front (on a non-fatbike), and the feeling is superlative. I honestly don't care that the wheel on the back is a meager 2.6", this is just too good, regardless of bicycle. It's not for everyone though, since it's not a particularly cheap set-up.

Here's how you do it:

• Buy a narrow fatbike rim. Like a 65mm Sunringle Mulefut or Surly Rabbit Hole or hell, maybe even ZTR Hugo. Don't buy an 80mm rim unless you have very narrow brake calipers. How narrow? Hard to say in advance. XT seems to fit, but I wouldn't risk it.
• Lace this rim to a 110mm hub. This is highly unorthodox, but works just fine.
• Get the Fox 34 "PLUS" fork. There's only one. Be careful not to mess up and get an ordinary fork, this "PLUS" model is fairly unique. This one is expensive.
• Get a 3.8" fatbike tire.
• Bonus points: get a reliable 203mm rotor, like Shimano Ice Tech. Why? Well you now have a heavy front wheel, you need more stopping power. Plus, a larger rotor keeps the caliper away from the widest point of the spokes.

This set-up is the awesomest set-up. Interestingly enough, it works with both 26+ and 27.5+ wheels since the fork fits 27.5/3.8 provided of course you don't go overboard with too wide a rim.

 

[The duke]

I run no less than 3.8" on the front (on a non-fatbike), and the feeling is superlative. I honestly don't care that the wheel on the back is a meager 2.6", this is just too good, regardless of bicycle. It's not for everyone though, since it's not a particularly cheap set-up.

Here's how you do it:

• Buy a narrow fatbike rim. Like a 65mm Sunringle Mulefut or Surly Rabbit Hole or hell, maybe even ZTR Hugo. Don't buy an 80mm rim unless you have very narrow brake calipers. How narrow? Hard to say in advance. XT seems to fit, but I wouldn't risk it.
• Lace this rim to a 110mm hub. This is highly unorthodox, but works just fine.
• Get the Fox 34 "PLUS" fork. There's only one. Be careful not to mess up and get an ordinary fork, this "PLUS" model is fairly unique. This one is expensive.
• Get a 3.8" fatbike tire.
• Bonus points: get a reliable 203mm rotor, like Shimano Ice Tech. Why? Well you now have a heavy front wheel, you need more stopping power. Plus, a larger rotor keeps the caliper away from the widest point of the spokes.

This set-up is the awesomest set-up. Interestingly enough, it works with both 26+ and 27.5+ wheels since the fork fits 27.5/3.8 provided of course you don't go overboard with too wide a rim.

Ok, I'm confused. JRA said in the post previous to yours, something a lot of people say. A fatter tire on the back wheel is a good idea for increased traction for peddling uphill and for increased plushness to make up for the lack of a rear suspension. The front tire on the other hand, should be thinner so the bike doesn't pull you upright unnaturally, and you've already got suspension for dampening on the front end. Or that's what I thought the conventional wisdom was.

Did you by any chance ever figure out what the max size you could go up to was, without having to do the major surgery of rim and fork replacement? If you could go up to....say 3.25" plus tires without having to replace parts, is there enough additional plushness to add another half inch and probably more than an eighth of a pound in rotational weight?

 

[Dmitri]

Ok, I'm confused. JRA said in the post previous to yours, something a lot of people say. A fatter tire on the back wheel is a good idea for increased traction for peddling uphill and for increased plushness to make up for the lack of a rear suspension. The front tire on the other hand, should be thinner so the bike doesn't pull you upright unnaturally, and you've already got suspension for dampening on the front end. Or that's what I thought the conventional wisdom was.

Did you by any chance ever figure out what the max size you could go up to was, without having to do the major surgery of rim and fork replacement? If you could go up to....say 3.25" plus tires without having to replace parts, is there enough additional plushness to add another half inch and probably more than an eighth of a pound in rotational weight?

You are right about the conventional wisdom: typically the rear tire creates the movement, and the front tire is meant to roll. However, there are a few additional issues. One is cornering stability. A 3.6" tire has awful cornering experience. You have to really slow down and be very careful when turning. On 3.8", cornering is much more natural. So that's one thing. Another thing is absorption. A 3" or less tire gets displaced by a rock easily. You feel a very noticeable jolt if you hit it. Also, driving straight into the curb isn't an option because the tire is too thin to compensate. On 3.8" with a Fox fork this is painless.
I wish I could fit a fat rear tire, too. Sadly I cannot so I make do with what I can.