[Closed] Fat - 4" vs 5"

I think so. I'm a new convert mind but the extra cushion of the Bud over my Jumbo Jims is very noticable and I can run lower pressures without pinching. Grip, I don't know- I can't compare like with like there. But I'm a convert anyway.

OTOH 4.8 does look pretty stupid. I really like the look of a 4 inch bike.

What are you running now on the dune. Ta

ride predominantly on snow go 5", mainly normal trails go 4"

Firestarter, still a Bud and an original JJ because apparently ordering a second Bud is impossible. Got a Minion and a 4.8 JJ in the mail...

I'd be interested to see how a big tyre fits in the rear
I've only had fat a short time on a fat in the hardpack dry (oh remember those days fondly) the 4" jims just flew they seemed perfect

Bud definitely fits in the back, with about 6mm clearance at 9psi so not generous, but then Bud doesn't really pick up that much mud or snow. There's some pretty good resources for genuine tyre sizes, I think a Lou will fit too. I suspect I'll end up minion fbf front and bud rear for the winter but the fbf won't arrive for a couple of weeks.

(my fatter rear thinking is partly inspired by yet another blimmin flat today, I have to run 9psi in the back to avoid flatting every ride and that's too high with my light weight for the JJ to really work, so I'd dropped it to get it to grip in the snow and sssssssss. Still, you get a workout pumping fat tyres up. Maybe this is a JJ thing not a 4 inch thing but for me it just doesn't work well)

I'm a 5" fan. Big difference in cusioning allowing for faster speeds over rough ground as well as more float in the soft.
Bud both ends all year round for me.

Northwind a lou should fit then as they are meant to be a couple of mm smaller than a bud. I wonder if they would fit with the 2x10 or only with a 1x setup

Why are you getting trouble with flatting NW?

It was said of 5" (when it first appeared) that it was fairly mission-specific; there are certainly occasions where the additional floatation comes in handy, but most riding was OK, indeed better, with 4".

I reckon that may have changed a bit with the introduction of new/better/different tyre choices.

Of course, a 5" frame will always take 4" tyres so if taking a punt now, there's little to lose in going for the additional girth.

The other thing that might affect your choice would be the likelihood of also running B+ (in the same or another frame). Give that there are 3.25" Chubby tyres available, it could be argued that the step up to 4" (in reality mostly 3.8") barely warrants the effort and that a B+ [i]plus[/i] a 5" bike covers a better spectrum of possibilities.

I run Husker Dus in summer and Dillinger 5s in winter - noticeably more grip, particularly with the sloppy mud of late. I've also got a 29+ with 3" Knards which is great for summer, but absolutely no comparison to a 4" tyred bike on things like soft sand. Off to the arctic in 5 weeks - definitely a case where fatter is better.

Moonlander with 5psi Bud/Lou vs OOF with Floaters as low as you dare with the shit rims feels as different capability wise on snow and sand/shingle as the OOF did compared to a normal mtb.

Definitely do something about your set up Northwind. Running bud/Lou at 9psi is missing the point!

Try bending zee kneez.

rOcKeTdOg - Member
ride predominantly on snow go 5", mainly normal trails go 4"

And 5" for beaches and sand dunes are a little better on softer stuff than 4"er's

divenwob - Member

Why are you getting trouble with flatting NW?

Basically riding it like a normal bike. Today's was a rider error really, a rock drop where you really want to clear some rocks before landing, but still the sort of thing a mountain bike needs to be able to deal with. One was gold run at innerleithen, nothing in particular, just a rough chunk of trail up near the top.

This isn't a big criticism or anything, I'm asking quite a lot of the bike. But it seems to me that wider tyres increase the capability of the bike quite a lot. And, well, as far as I'm concerned the ideal width of tyre is about 2.35 so it's not like 4 inches suddenly becomes super light or efficient 😆

johnnystorm - Member

Definitely do something about your set up Northwind. Running bud/Lou at 9psi is missing the point!

My bud's at 5 usually, it's a Jumbo Jim on the rear that needs the 9. Which also misses the point really, it's not working like a fat bike tyre should, but that's just how it needs to be. I've got a 4.8 in the post so I'll be able to see for sure if it's the width or it's just the lightweight tyre.

@menmuir, if I didn't bend zee kneez I wouldn't get 10 feet 😆

Fat - 4" vs 5"

molgrips - Member

Any difference practically?

About an inch! 😀

5" have more of a tendency to autosteer I've found. When I was riding a grove in snow seemed harder to hold lines and the like . Gone back to 4" on the front. Also consider rim width; 80mm plus for a good profile with 5" tires.