When we first stocked FatBikes you had the frame material choice of steel and, um, steel. Because Surly was the only brand we dealt with for FatBikes (and frankly the only sorta mainstream manufacturer making them) and because Surly only makes steel bikes that was the single option available to us.
That all changed when Surly’s cousin Salsa entered the FatBike market. Suddenly we had aluminum and even a titanium model on offer. Then in 2013 Salsa became one of the first FatBike manufacturers to come out with a carbon frame.
So, what’s right for you, and why? Honestly we don’t think that frame material makes the same difference for FatBikes as it does with road bikes or mountain bikes. This is mainly due to the larger volume, lower pressure tires on a FatBike, which somewhat mute the inherent differences in frame material, much the same way dual suspension mountain bike frame material doesn’t affect ride characteristics as much because the bike is equipped with shocks front and rear. FatBike tires are in essence mini shocks.
Frame material does of course make a difference to weight. We love steel bikes, and high end steel doesn’t have as much of a weight penalty as you might think, but everything else being equal it is indeed heavier than other materials. Good quality aluminum is always going to be at least a bit lighter than steel, and carbon is usually lighter than aluminum, though to difference isn’t always as great. Titanium is actually often a bit heavier than carbon and even aluminum but is arguably the most robust frame material out there and is sought after for its resilience especially when investing in a bike you plan to ride for a long time.
Speaking of resilience, steel has similar characteristics to titanium except that, sadly, it can rust. High end stainless steel tubing, like the stuff used in all the steel FatBikes we sell, is pretty durable but at the very least you’re bound to see a little surface rust around some of the welds after time. That’s most an aesthetic issue, and in our opinion not a big one, but it is unique to steel frames.
We get lots of questions about the durability of carbon fiber frames in the winter. Here’s our response in a nutshell: Don’t worry about it. We’ve been riding carbon bikes all winter for some time now with any temperature related issues at all. Heck, the web editor road a Cannondale Scalpel with flexible carbon chain stays as a commuter year ’round for a couple of years with absolutely no problem. We see no reason why this would be any different for carbon FatBikes. Maybe there’s just a lingering perception that plastic is fragile, likely because 50 years ago plastic WAS fragile, and now any composite material is suspect. Times have changed, and modern carbon fiber composites are plenty strong no matter the ambient temperature.
The last word on FatBike frame material almost isn’t worth mentioning because it’s so obvious, but what the heck…different materials have fairly distinct aesthetic differences. Steel and titanium tubes are small diameter, aluminum is larger (though the actual tube walls are thinner) and due partly to newer hydroforming techniques aluminum tubes can offer less traditional shaping, and carbon can be laid up or molded into virtually any shape you want. These shapes do effect ride characteristics but again, because of the large low pressure tires the affect is muted. In the end it becomes an aesthetic thing almost as much as a weight thing, and we get that. Maybe you have the coin to splurge for a carbon FatBike and really like the idea of getting the lightest frame out there but the classic look of steel always wins you over. Good for you. Buy what excites you and you’ll ride it more, no matter if it’s because of a functional or an aesthetic difference.