For 8 years my kids have been coming fatbikepacking with me. This is the story of how I chose, and what I did to my kids’ first fatbike to help them succeed in as young fatbikepackers.
Disclosure: I have bought all the Salsa fatbikes mentioned in this article. Salsa did send Tadhg some racks and accessories for his fatbike when they saw how cool he was. I have affiliate links in my articles and receive compensation for some of the things purchased through links. I am not for sale, and I make it clear when I link to things that I don’t use.
What’s a Fatbike, What I Think It’s For, Why They Make Good Kids’ Bikes
Fatbikes were invented in the late ’90s and early ’00s by Rey Molino and Mark Gronewald with the intent of riding on sand and snow respectively. The Surly Pugsley was the first mass-market fatbike in 2005, and by 2011 there were several competing brands. By 2015, nearly every manufacturer had a fatbike in their lineup, and the trend has been slowing down since then.
The original concept of a bike with wide tires that can be run at low pressure to spread them out and float on top of loose surfaces still applies. Snow, gravel, scree, and sand are all surfaces that would be less rideable without a fatbike. The tradeoff is wheel and tire weight, but with thinner rim walls and tire sidewalls allowed by the low pressures, some of that can be mitigated.
Kids have much lower power relative to the weight of themselves plus the bike. Kids low weight means that suspension works poorly for them, by the time it starts to move, they’ve absorbed the bumps with their little bodies. Fatbikes can help with this. The huge tires will roll over more small obstacles than small narrow tires, this helps kids keep their momentum, and not get forced off their track. Also, the high volume of a supple fatbike tire can act as suspension for kids, and it will absorb a couple of inches of trail irregularity.
For this reason, my kids have chosen fatbikes as their primary bikepacking bikes even though that might seem counter-intuitive to someone who hasn’t ridden a good fatbike. They have only ridden high quality fatbikes, never junky ones with stiff tires.
What My Kids’ First Fatbike is
I started with a 2013 Salsa Mukluk in size XS. At the time, this offered the best standover height of any fatbike, and I had been enjoying my own Salsa Mukluk Ti well enough that I knew the geometry was well thought out. It also offered the Alternator dropouts to convert it to singlespeed, or to shorten the chainstays for smaller tires, which was my use for them.
What I did
My kids were not tall enough to meet the intended rider height. So I decided to alter the bike a bit to make it better meet their needs.
First, I was concerned that a 4’6″ kid was not going to be comfortable pedalling the stock 170mm cranks. After a bit of research, (which suggested I should ride longer cranks), I started looking for short cranks, ideally 140mm which would cover them until they reached about 5′ tall. Fat bikes have wide bottom brackets, and the selection of cranks isn’t great. I had a choice of a junky bottom bracket and commonly available cranks, or to go with Profile Racing cranks I went with the Profile, since I had been using them on my own bike for over a year, and they offered a lot of low gear options.
Next, I wanted low gears for the kids. Lugging a bike that I hoped would be only half their weight up a hill meant the kids would want as low gears as they could get. Back then, 1x gearing was in its very expensive infancy, so I went with a 12-36 cassette, and a single 23 tooth chainring for the front. Any lower of gearing, and the kids would be walking anyway.
Because of the shorter cranks, the bike had more clearance for the cranks, and I took advantage of this by putting smaller diameter tires on to gain some more standover height. In 2000 or 2001, Specialized accidentally invented the first really good fatbike tire. I got them for riding the ITI, they are a pretty generous 3″, but they have nice supple sidewalls for riding on snow (which made them a crappy downhill tire) and they drop the bottom bracket by about 20mm. The kids are light enough that they can still run these tires at just over ambient pressure and still have more float than I ever have.
These days, there are a number of good options for 3″ wide 26″ tires. Again, because kids are light, running them on 80mm rims is not a problem. For that matter, though many people have told me it wouldn’t work, I have run 3″ tires on my own 80mm rims with no problems.
With the seat dropped down low enough for the kids to pedal, the stock reach was pretty reasonable due to the high front end relative to the seat. I put some On-One Mary bars on the bike to make the reach a bit easier, and a 35mm stem kept the bars close in. My kids were around 8 1/2 when they were tall enough and skilled enough to ride it in the mountains. They weren’t doing wheelies or jumps, but they could ride.
Why Not 24″ wheels?
Firstly, at the time there were no 24″ wheeled fatbikes. Beyond that, when the 24″ wheeled fatbikes did come out, in time for Fiona to ride one, I didn’t get one since the first ones weren’t really much smaller than what we had.
The second disadvantage to the 24″ wheels was that the smaller diameter of the wheel makes for much more skittish handling. The approach angle to the snow is sharper too. On top of that, the tire selection for 24″ wheels on fatbikes is limited. None of the 24″ tires that I know of have flexible enough sidewalls that a 50 pound kid can take advantage of the tire’s full width. The stiff sidewalls also make the pedalling more difficult at low pressures. I did not want my kids using up their kid-sized power to overcome tire hysteresis.
These days there are some good 24″ wheeled bikes with 3″ “plus” size tires, and I recommend these for both general bikepacking and for riding on groomed, or mostly groomed snow. My favourite of these is the Timberjack 24 from Salsa.
What About 20″ Wheels?
What I said above is even more true about 20″ wheels. Maybe some kids are able to get through snow on 20″ fatbike wheels, but I’ve never heard of them (cue those kids’ parents), and I know that my kids just didn’t have the power at that size to ride the 20″ wheels in ungroomed snow. This is not a dismissal of the whole concept, indeed there are many good reasons to go to 20″ 3″ wide tires for kids.
Tubes aren’t really that bad, other than their fragility. But when it comes to fatbikes, tubes suck. When it came to my kids’ first fatbike, that applies even more. Kids fatbikes need to be tubeless for riding on ungroomed snow. It isn’t a subtle difference like hardpacked dirt with a mountain bike, it is absolutely essential.
The reasons are many, but mostly, because kids are running seriously low pressure, tubes will pull away from the sides of the tire. This makes a band of higher pressure down the centerline of the tire, and floppy sidewalls at the edge. This is the worst case for both flotation and rolling resistance, not to mention how terrible it is for cornering.
These days there are a selection of great tubeless-ready fatbike tires to chose from, but for me, the only choice was “ghetto” tubeless systems. These are notoriously unreliable in the cold, but I have had good success with them with a variety of systems. My first rule is never use Gorilla tape as rim tape. It reacts with the sealant and renders it useless within weeks. For the kids’ bike, I used a 24″ tube split “the split tube method” and then added latex moulding compound around the edge of the bead and rim to help stick the bead, and I added a plastic rim strip to either side of the bead shelf on the rim to help keep the tire toward the edge.
The Trail Forward
This year, Fiona has outgrown my Kids’ first fatbike, she has been borrowing her mom’s, but some time soon, we’ll want to go as a family. Most likely, she’ll inherit her brother’s bike and he’ll move to an XL (He’s way oversized for his size small, all the seatpost is showing)
Though I’ll be sad to see it go, I hope I find a good home for it.