I couple years ago Mongoose introduced a dirt cheap fat-bike available at Wal-Mart. Many have dubbed it the Wal-Goose and view the mainstream fat-bike offering as a joke. It too have gotten chuckle out of some of the reviews going around the internet. It wasn't until last spring that considered getting one when Mongoose introduced a kid's fat-bike called the Massif, with 4 inch wide, 20 inch diameter wheels.
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| Big D....un-packaging |
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| first ride around the yard |
I've been riding fat-bikes for about tens years , my kids have been on bikes since they could straddle a strider, so it was only natural that they would have their own fat-bike. I showed my youngest son an image of the bike online, he instantly wanted it, but would have to wait until fall for me to finally pull the trigger and purchase it. Once we had it in hand I assembled it immediately, too say it was heavy was a gross understatement. My digital fishing scale read just over 40 pounds out of the box. I was shocked, my son only weighs 53 pounds, as a ratio I couldn't imagine myself riding a bike that weighed 160 pounds +.
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| cut me |
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| careful measuring |
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| down tube completely welded in place, awaiting removal of top tube |
Something had to be done....... First, in my basement, I drilled the rims with a hole saw like any other non-cutout wheel. At work, I moved on to the frame, it had a useless brake bridge and a kickstand mount, both were removed with an angle grinder. As I stood there, grinder in hand, gazing at the enormous top tube and down tube, the spinning wheel called to me....."CUT IT". I knew this would require a lot more work if I cut the tubes and re-welded smaller ones in their place, but as the blade slashed through the first tube I was committed. I was however smart enough not to cut both at the same time, instead I removed one tube and replaced it before cutting the other. This would ensure the frame kept it's original geometry. I'm not saying the geometry was perfect, but I wasn't about to go messing with a bike that my son was already riding just fine. The tube exchange went well and a co-worker volunteered to spray-paint it while I ate some snacks and finished cleaning up the holes I drilled in the rims a few days before.
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| precision mitering |
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| I lucked out here...the 1" OD tubing fit right inside of the old tube, saving a lot of time trying to clean up the joint where the new tube would interface the chain stays and seat tube |
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| welded head tube...remarkably the head set still works. I left it in place as a heat sink and to keep the head tube round. I planned on replacing it after it was severely heated but it worked just fine with some new grease. |
Back at home I began scouring my old parts bins for lighter weight items. I found an old carbon seat post, and handle bars, Shimano 105 rear derailleur, and an old Syncros road stem. I purchased new..... a saddle, a chain, Avid brake levers, and a 165 mm crank set, as well as an isis bottom bracket to fit it. I kept the original crappy disc brakes since they work just fine and I was tired of blowing money on something that wasn't going to be worth much in the end anyway.
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| finished and ready for paint |
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| drilled wheels......... obviously |
I was hopeful to get my hands on a set of tires made for the new Specialized 20" kids fat-bike but that hasn't panned out yet. The tires supplied with the bike are perhaps the shittiest hoops of rubber ever manufactured. I failed to weigh them, but together they are heavy enough to give you a hernia. The tires provide absolutely zero traction on anything but smooth asphalt. To fix this (somewhat) I took an angle grinder with a quarter inch wide hard wheel and grooved both of the tires. This took such a long time I siped the front tire more like that of something used on a motorcycle for sand dunes. The rear one was grooved perpendicular to it's circumference to provide traction under power. Neither of them worked all that well on the first ride in the snow, but markedly better than the slicks.
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| First ride in the snow |
When the bike was all finished it turned out looking pretty good. The final scale test was disappointing, I managed to only drop the weight a little more than five pounds. It was a fun project but hopefully by next year my son will be able to fit on one of the 24" wheeled fat-bikes now available. On the other hand, Big D likes riding the bike and is having fun with it so that's all that really matters.
