How do I determine a suitable handlebar width on a fatbike?

Fatbike owners seem to be fond of using lavishly wide handlebars. They also don't just go from 640mm or 660mm to 680mm or 700mm, but often to 720mm or 740mm. I'm assuming their shoulders couldn't be that wide, and they choose this width for control, even at the risk of having a posture typical of motorcyclists rather than cyclists.

Maybe this is due to the force needed. After riding a fatbike a bit, I'm surprised at the amount of force it takes to return to straight. During a left turn, for example, the handlebar exerts quite a strong pressure. One needs to push with the left arm, or else the bike would turn even further to the left. Likewise, returning to a straight line takes significant pressure.

This is very different from a road bike, where only a hint of an effort needs to be exerted with the arms to turn and to return to a straight line. The hub on a fatbike is only very slightly in front of the line of the steerer, whereas on a road bike or MTB, the hub is significantly in front of that line. On ancient bikes a curvature at the bottom of the fork illustrates this very well. Perhaps the position of the hub on fatbikes almost right under the steerer is both necessary and requires such pressure during turns.

How do I determine a suitable size for a fatbike handlebar? Is it established that it needs to be unusually large to make steering easier? Once the handlebar exceeds 720mm, it becomes a nuisance to pass through doors—a convenience in the winter when all work needs to be done indoors, and so I'm wondering whether such a width is compelling.

• I have seen bars advertised at 820mm, Low 700's it pretty typical these days. Jan 3, 2022 at 5:08
• @mattnz ..and forever after the cyclist needs to carry a wrench and mini torque wrench to be able to undo/redo the stem before/after passing through doors; is that the idea? Jan 3, 2022 at 13:55
• Note that the easy way to get a bike through doors, unless it's got full mudguards, is to put it up on the back wheel and walk it that way. Then you can tilt the bars so they and the wheel fit through doorways. That's how I take mine through the gate into the back garden for cleaning Jan 3, 2022 at 16:37
• @ChrisH 26x4 tires have a circumference of 239.2 cm, hence a diameter of 76.1 cm, which wouldn't fit directly. Hence (on the back wheel) you first push the wheel through, then turn the handlebar to make them pass. This assumes that you don't have a door or a wall in your way. This would not work, for example, to pass through a door-wide passage. I wish I had experimented with this before frost set in. Jan 3, 2022 at 17:02
• @Sam, no, you don't turn the wheel horizontal, but put both bars and front wheel on a diagonal. Because the front wheel isn't touching the ground you can do that. 26x4 and 740mm bars should fit through a passage of about 600mm that way (assuming slightly simplified geometry). You can draw it at 1/10 scale: a rectangle for the tyre and a line for the bars combine to form a cross. Then join adjacent points of the cross giving 2 parallel diagonal lines (front left of tyre to left tip of bars, right tip of bars to back right of tyre) and measure the distance between the lines Jan 3, 2022 at 18:33

I don't own wide bars, but on some bikes I ride, a narrower hand position feels faster and is also good for a headwind. Downside it is more upper-arm required to steer in a narrow hand position, so you're putting more effort in to manoever. Thus its good for long straights.

Conversely a wider position is better when you're tired, or going fast, or need leverage to manage turns/balance.

If you already have one, try riding with your hands closer to the center line and see how it feels to you.

• Its common to start wide, move the controls and grips inboard until you find the width you like, then trim bars to size. Jan 3, 2022 at 5:11

Note for reader: "fat" in this context refers to having abnormally wide tires on the bicycle for riding in snow and sand and has nothing to do with the rider's physique.

Handlebar widths in excess of 700mm are nothing unusual on modern off-road bicycles. Heck, even the most budget-friendly hardtails (usually with older or more traditional design) are coming with bars that wide now; the Giant Talon has 780mm(!) bars stock from the factory. The justification and benefits of this setup (especially in conjunction with a short stem) are best described under a different question.

I don't see an issue with emulating a motorcyclist's posture if that brings the rider greater benefits. There's probably a Velominati rule against it though...

The large mass of a fatbike wheel, tire, and fork certainly do make it harder to steer. However, the steering geometry is the more significant factor. This is partially discussed in your previous question here: What are, if any, the signature postural differences between riding a 26″ bike and a 29″ bike?

Notably, the head tube angle on a modern fatbike will be fairly slack. This means there is more wheel flop to overcome for a given steering angle, so yes, more effort will be required. This is in the interest of riding stability on unpaved trails. Your road bike benefits from less stability, not more.

I disagree with this assertion:

The hub on a fatbike is only very slightly in front of the line of the steerer, whereas on a road bike or MTB, the hub is significantly in front of that line.

Fork offsets are similar if not identical between fat and regular forks. For example, the RockShox Bluto is available in the usual 51mm offset.

Determining the ideal handlebar width here has no specific relation to fatbikes in my opinion. General mountain bike handlebar width sizing considerations should be applied.

• @Sam I'm happy to write about determining ideal bar width if you'd like (on one of the existing bar width questions). Jan 3, 2022 at 5:35
• I don't think Velominati cares about mountain bikes at all. Jan 3, 2022 at 12:03
• For comparison my entry-level hardtail from 2017 (mechanical specs outdated when built) has 720mm and feels really wide compared to my hybrid that I cut down from 650 to 600mm. Even at 720 it still looks narrow compared to some I ride with. The different hand position to a road bike make comparisons rather meaningless. Jan 3, 2022 at 16:35
• @MaplePanda Re: "I disagree with this assertion" I concur with your disagreement. I drew a few lines extending steerers, and the fork offsets become quite visible. Re: "General mountain bike handlebar width sizing considerations should be applied": Care to provide even a brief pointer? It's worth mentioning that I'm using a fatbike as a winter road bike. I'm not doing "technical terrains" on ice/snow, just snowy/icy/slushy paths that have been compacted by pedestrians, then refrozen. Hence very wide handlebars seem pointless. Jan 3, 2022 at 22:52
• @Sam There’s varying schools of thought (some use a mathematical formula like 0.44 × your height, some say the push up method, etc). I like to just go by personal preference by more or less mentally graphing bar width against how much you like that width’s feeling. Generally, narrower for less aggressive riding, wider for more aggressive, although there are many exceptions (eg. pro enduro racer Jesse Melamed at 5’7 is on 740mm bars). Usual range is 720-820mm. Some other factors include going narrower for XC racing (easier to pass other riders with narrower bars, and somewhat more aero). Jan 4, 2022 at 10:12