Would it replace your mountain bike?
 

This is the thought that is bouncing around in my head but I fully admit I have OCD and shopping issues; I am dead serious on this.

On top of that I am very impulsive and will throw money away just to get the urges to stop. But this time I am trying to be really logical about it so please read the entire thing before you chime in.

I had for years the same bike but hardly used a Specialized Hardtail that I purchased when married and kept for the years after the divorce. Then one day I asked my fiance if she wanted to go for a bike ride; well that spiraled down to her and I shopping and me on impulse buying a Specialized Hybrid and a Trek Fuel EX5 and keep in mind I actually wanted a fat bike but basically let myself be talked out of it; why? It really doesn't matter.

So anyway that was two years ago. Since then I found I like both things from paths that are paved or gravel and days to venture in the woods with a mountain bike for things like rocks don't go over well with a hybrid.

Now jumping to the present time, I got tired how heavy and hard it is to ride that hybrid. Yeah it's easier to build speed and go fast versus the mountain bike but still get passed by road and gravel bikes. Well since I am not a road bike kind of guy I just, well actually my fiance bought me the Trek Checkpoint ALR5 which is on back-order with an eta of September at the earliest.

So in the meantime using what I have but the itch for the fat bike is growing and growing and getting harder to ignore. So if I let myself do it the two I will consider is:
Surly Ice Cream Truck
or
Trek Farley 5

So I ask you:
1. Should I proceed knowing all of this?
2. Whether yes or not which would you choose and why?
3. Big question would this be a replacement to your mountain bike or you would keep both?

Note I am leaning towards the Trek due to me liking them and the company, plus it's a lot lighter than the Surly.

I kind of lost track which MTB you currently have or have on order... or what type of riding you intend to do. Obviously the one you already have is the most sensible choice for the task.
But for non-crazy MTB riding you can use a fatbike easily. Fatbike mainly has an advantage in that it works great on snow/sand and doesn't require complex suspension. If you go where there is no trak yet, it even is better than an MTB.
One of my riding scenarios is to go over housing developments when the excavators pile up mountains of dirt and create big holes..... the fatbike is the ideal bike for that.

Can't tell of the two you proposed which is better, you didn't list why you picked these. I'm very happy with my Sturgis NX for half the cost. The only Achilles heel of most fatbikes are the weak rear hubs (including the ones you listed). The only one really better is the Canyon Dude that uses DT Swiss hubs.

N+1 always is the response you will get on this forum. but it really depends on your riding. Just keep both for a while and see which you ride the most.

Will it replace my mountain bike?
 

After looking at the fat bikes, I settled on the 29+ TREK Stache 5. It totally replaced my mountain bike. My hardtail mountain bike now has Fat Apples on it for knock around service. I do not think a 4" or 5" fatty would replace a mountain bike, though.

I run the Stache with the stock Chupacabra tubeless tires running about 20# rear, 22# front. Our single trek has lots of tree roots and the 29+ tires roll over them with little or no issue. I feel much more secure and stable, go faster on the downhills, than on my 29" mountain bike. Much more satisfying ride.

Only if you want the fat bike to replace the MTB. I am longer longer into gravity rushes, so I switched to a fat bike. It is slower and a pig on the uphill, but it will take you anywhere and with more sure footed confidence.
As I have posted before: MTBs are for single track and Fat bikes are for no track

I am thinking about trying some of the local trails with my fatbike. I figure some of the parts I have trouble with will be easier with bigger tires. Than again, I might rip a sidewall. If it ever stops raining for a week

I picked up a fat bike a few weeks ago and I really feel that everyone should own a fat bike.

It's an absolute blast to ride. It's like a mix of bike riding and those moon bounce balls for toddlers.

I've ridden it on a mix of trails and pavement, including single track. It's slow, but because of the weight it's still a great work out. The reaction from those tires is endless and it has flotation to match. I took a family ride with my kids where we hit some sandy sections. I honestly felt sorry for my kids as they got the sand and started swerving about to maintain momentum as their tires sunk into sand.

I love road riding, I love my XC bike. I can really get those bikes up to speed to satisfy that desire. The fat bike, can it replace a mountain bike? It can replace all your bikes.

It's been decided. I am putting the Trek Fuel up for sale and when I can buy the fat bike. I primarily gravel anyway.

Good decision. A fatty can adequately do most of what a mtb can, but not the other way around.

I have a possible sale of my bike. The guy is on the fence but I can tell really interested. Being that I don't have to sell the bike I am being a stickler on the price and I know that is a sticky point for him but again I don't have to sell the bike I just want to sell the bike to cover the cost of the recently purchased Gravel and free up space for the FB once I get the credit cards paid off and I have cash for the cost of the bike and the parts I need on my bike rack so I can haul the bike.

Bike is sold. Next task: credit cards. After that Fat Bike.

In the meantime going to do the endless search. So far it's between Surly, Trek and yes Specialized. The later recently got added into the mix.

I looked at other brands and so far I am iffy about the others. I can say the Cannondale with the one bar thing is just hideous IMHO.

if I had to buy another fat bike it would be the lightest one I could find, my farley 7 with a rack weighs in around 35 lbs, it is tough to move around
it is a great bike, and I enjoy riding it,
I have seen a pivot les build that was very light, and weight would be a major consideration for me.
as it stands now my fat bike has lights on it, and reserved for winter rides only, if it came in 10 lbs lighter I would use it more during the summer

It really depends on your usage.

I personally use only a Fat bike for all my fun rides and a hybrid to commute.

________
+ 1. Sold my Moots YBB when I bought my second fatty (rigid).,. contiinues to be MY only mtb.

Having just returned from Moab where I used a full suspension mtb (Trek EX7 Fuel) on various routes, including Slickrock Trail, I'd say a rigid fat bike does not replace a FS mtb - not even close. Even with my fat tires (Spesh fatboy with 4.6 Ground Controls) I would have been beaten up and far more selective picking lines. On my return it was a bit of a wake up call to again do downhill on my FB.

Doesn't mean I don't love my FB, but it isn't equal to a dedicated mtb.

______________________________________________________
I.Y.O. (to each their own)
I ride Moab (Slickrock Tr, Klondike, Phil's, Mary's, home and others) twice a year on my fatty.
All bikes have their limitations (including fatties) but I really wouldn't want to own any other bike (hated Full Squish R. Mtn and prefer rigid fatty over my former Moots YBB) and it was (IMO) the ideal ride for me on the GDMBR.

There's no doubt one can ride fat bikes as mtb's.. I do it, And I have decided as a one bike to do the most off road to choose one, but it's a stretch beyond to say they will perform as well as dedicated full suspension mtb's for technical riding (unless they are full suspension fatties perhaps). It's like people who say they can gravel bike the same as an mtb.. nah ah.

I own and love a fat bike but it's not the same as a FS mtb. How could it be. I definitely downgrade what is possible when on one. So the question is more: would a fat bike replace an mtb for less than optimum performance - probably. Wanna get the most possible out of mtbing - use an mtb.

I see you ride a Corvus 27.5x2.8 in summer. In which case you've basically turned your fatbike into a defacto rigid mtb. Does a rigid mtb replace a FS mtb? Not really. You can use one but it's not the same level of performance.

I hadn't been riding my fat bike for a while. Rode it over the weekend and I had forgotten how much the wide pedal stance bothers me. I need to ride it more to see if that goes away.

But I am thinking that a 29+ could probably have replaced the mtb and the fatbike.

It does take some getting used to (the Q factor).

I've said before that I am working towards a long term goal of N=2 stable of common use bikes, 3 if you count my FG.
That doesn't include various project bikes.

In a perfect world the first would be an endurance frame all roads bike. Fit road tires for pavement and gravel tires for off road.
This covers: commuting, road riding, touring, randos, gravel riding, easy bikepacking etc...

The second would be a full suspension fat bike (26x4-4.5) with the lightest frame practical (a balance of durability and weight). Going lighter where you can compensates somewhat for the increase in weight from the suspension.
Lockouts for suspension, dropper post and second 29r wheelset.
29x3 retains the same BB height as 26x4.
This covers: Sand/snow, trails, bikepacking, technical mtb. With the 26 wheelset you are a fatbike and with the 29r set you are basically a FS mtb.

The OP is long, rambling and hard to follow, so I can’t answer questions 1 and 2.

But to answer #3...

I currently own. FS MTB and a rigid Fat Bike. The fat bike is no substitute for the FS mtb. Not even close.

I bought the fat bike after moving to Upstate NY where the winters serve up 5 months of trails in various stages and combinations of muddy, leaf-choked, snowy, slushy, and icy. This is where the fat tires shine.

But outside of that, I find a standard tired bike outperforms it in every way I can think of. And if I were to move back to Virginia I would likely sell the fatty.

Granted it is not fair to compare a rigid bike to a FS, but even if I was talking about a HT, I would still go for either a standard or Plus bike over a fatty for non-sloppy/snowy riding.

Not sure if this really answers your question, because I am unclear what exactly you want to do with the bike. You mention gravel and pavement but I think you already have a hybrid.

If you could condense you question to a few sentences you will get better answers. You can leave you marital history out for the sake of conciseness.

Hah hah! I think it boils down to this:

The only question should be: Can you afford it? If so, enjoy your hobby. It doesn't have to be logical.

It's funny how people agonize about some things but think it's normal to spend similar amounts on travel for a week or two that will yield nothing but a memory and lingering sun burn after it's over. I took a "staycation" last summer and spent the money I saved on my fat bike.

I ride a fat bike year-round, the carbon frame is a weight saver.
Farly 9.6.

^^^This. Fat tires are not substitute for suspension. I spent one summer trying to use fat bike only. Never again. Got too beat up.