Build a light and fun single-speed cruiser from a Trek 3700
The concept was to build a city bike with the comfort of a cruiser. Or a cruiser that doesn’t weigh 40 lbs (18 kg) and handles well. Or maybe a mountain bike that doesn’t make you look like a jackass riding through traffic with 780mm wide bars. Whatever, I really just wanted something simple, light, relaxed, with good handling. If you look at what’s available, it’s almost like this bike doesn’t exist. City bikes are maneuverable but not very capable and can’t fit fat tires. Most cruisers are stupid heavy and slow. Some of these hybrids/comfort bikes have head tubes that are a foot long and a feet forward position that makes standing up or popping up a curb a ridiculous task. And the streets of New Orleans are too beat up to ride anything that puts weight on your hands. So basically, it’s a 26 to 650b mtb conversion with cruiser bars.
The frame is a 2007/8 Trek 3700 entry level hardtail mtb, received in a trade. It’s aluminum and overbuilt since Trek has always offered a lifetime warranty on their frames. The same basic design was used for a decade, starting at the top of the line and working its way down over the years. The only remarkable feature is that Trek made a bolt-on disc brake mount for the rear, so they could use the same frame at different price points with different kit.
The chromoly fork is from an REI hybrid. It has mounts for disc brakes, fenders, and a rack, but is otherwise nothing special. It does weigh 75% less than the one that came on the trek.
Handlebars are literally from the trash. An old, tarnished set of steel bars from someone’s cruiser with curves that evoke the classics of the 1950s. They’re fitted with a set of extra cushy supacaz foam grips (on sale for only $10!)
Wheels were made by dtSwiss for a scott mtb. They came from FB marketplace for around $100 and are tubeless and lightweight. I had to fix a serious dent, fit qr end caps, remove the stickers with a razor and clean the bearings. I set them up single speed with a gusset bachelor tensioner and a 20T cog. Tires are vittoria terrano zero slick gravel tires, 650bx47.
Brakes are Shimano mt401 hydraulic and came with levers and 180mm rotors, found on ebay for $50. I had to learn how to bleed brakes to set up the rear.
The seatpost is flax carbon from Museeuw and was on sale for $30 down from $100+. The Terry Fly titanium rail saddle from ebay ($30) is light and surprisingly flexible and comfortable.
The rest of the drivetrain consists of parts I already had- a track crank and a 45t chainring and a magically smooth bottom bracket that was either in the trek or a different trash bike (I forget) and new Odyssey Grandstand V2 pedals.
I customized the frame by stripping the paint, removing the braze-ons, adding new hose guides smoothed with body filler, then I primed and painted it metallic cobalt blue.
I built a custom rack using aluminum brazing rods and tubing that mounts to the v-brake bosses on the frame. I had never seen this technique before starting this project, and luckily it looks good and functions like I’d hoped. I topped it off with a custom taillight mount and a cedar deck. It still needs some finishing, maybe paint.
At this point all that’s left is a bit of reflective accent paint (¡safety first!) and clear coat. I had originally planned to just finish the paint cheaply and quickly, but it exceeded my expectations and I want to do the clear coat right so I don’t ruin this. I’m going to let the paint cure longer and finish with a 2k clear instead of rustoleum junk.
Overall, I’m extremely happy with the bike and can’t wait to ride it again. It will fit every wheelset I own, so if I make it to the final 5, I’ll be sure to ride it on the trail with some 26” mtb tires and go for a speed record on my 700x30 road wheels for your entertainment. All in I’ve spent about $400 but buying everything full retail would have cost over $1200. In closing, I love you all, please vote for me.