If you’ve been following Bikes of the Bunch for the past few years you’ll probably be familiar with Francis Lim’s handiwork. In 2017 he shared the story of his Factor O2 ultralight homebuild, and in 2020 he told us about the Focus Izalco Max Disc 9 that he also built at home. Well, the latest delicacy to come out of the ‘FL Kitchen’, as his friends call it, is something a little different: an ultralight homebuilt mountain bike. Take it away, Francis.
We are all in awe of the bikes that Dangerholm can come up with, technically and aesthetically, but not everyone has the deep budget and technical know-how to work on their bikes at that level. This build bridges the void between stock bikes and those creations. It’s something any bike enthusiast can do; a reasonably priced bike that can hold its own in terms of aesthetics and weight against all the superbikes out there.
Hong Kong has a lot of MTB trails and a robust MTB scene. I wear my road biking heart on my sleeve but sometimes, especially on colder days, I wish there was an MTB in our cramped apartment that I could take for a two-hour ride in Lantau Island where we live. I’d love to sneak onto small village roads, climb the steep hill to the Big Buddha or ride the big, new bike park built on the south side. And as someone not technically proficient off-road, I’d need the bike to be light for an easier carry!
In short, my goal was to build a light and reasonably priced MTB, that performs as well and looks as good as any top model!
I had some components lying around, among them a grey-padded Berk Lupina saddle. This led me to decide on a grey frame colorway. I went with an open-mold frame that goes by FM-199 SL and had it custom-painted matte gray (pantone: Cool Gray 9C). For me this colorway highlights the curves and edges of the frame and goes with any accent color for components. It’s also the lightest boot axle frame in the open-mold market and the size S geometry is just what I was looking for.
I wanted to try carbon MTB wheels this time and with good experience from my road wheels in the last build, I went with the same open mold supplier. Rims were 33 mm wide, 25 mm deep, they had a 27 mm internal hookless opening and were tubeless ready. The wheels were built with DR lightweight hubs (308 g per pair) and Pillar 1420 spokes.
All of this was done through AliExpress. As you might know, most sellers don’t offer the greatest customer service but with a little bit of patience and a couple more weeks waiting, everything arrived as ordered.
Unlike my previous road builds where I had a set build list that I followed, this one took more of a spec-as-we-go approach. The pandemic is preventing full bike shop inventories and many items were unavailable. I went with shiny orange forks by Fox as they just arrived in time at the local bike dealer.
I really wanted to use grip shifters as I prefer the simplicity of use and cockpit cleanliness that they offer but since they are only offered as an aftermarket purchase and not with the complete set, I knew I had to cobble together a groupset.
I started with a SRAM GX 12 grip shifter and rear derailleur. I lucked out in the local second-hand market when I found some weightweenie-favorite Raceface Next SL crank arms, only to get disappointed when my usual 30T chainrings were not available in any color. I did see some orange-anodized 28s which were small, but then lucked out again when I found some Leonardi Racing 12s cassettes with a 9-49T configuration that gives a 533% range and a 0.50-3.11 ratio! With some more orange Leonardi Racing bits I had my accent color on point!
Most of these purchases were done online which, even if we want to support local shops, will be more convenient as product availability is in real-time and you don’t have to be exposed to crowds – important given the regulations currently in place.
I wanted to keep the unbranded theme for the cockpit except for the fact that I have an MCFK handlebar which was originally 680 mm long, and then had one end damaged in a crash. I sawed it off and repurposed it as a 660 mm flatbar.
I wanted to use tan sidewall tires so I was left with either the new Schwalbe Super Races or Continental Racesport Bernsteins. Despite past difficulties when using Continental MTB tires in tubeless setups, and not having a compressor pump at home to pop the tires onto the rims, I still went with them because of the darker, more ‘orangy’ sidewalls, bigger knobs and harder rubber. After a couple of days letting the tires and sealant set, rotating the tires and letting it lie on both sides, I was able to pop them onto the rims.
The build was straightforward and completed within one chilly February day, with house chores and errands in between, while my wife was comfortably snuggled on the couch minding her own business. After I spent a little bit of extra time bleeding the brakes and tinkering with the fork rebound/compression, it was ready to test.
Because my off-road pedals didn’t arrive in time, I had to use my road pedals and shoes for a quick shakedown. As you can see from the photos, I had so much fun!
In the end I spent less than US$3,000 for all the stuff that I didn’t already have, which puts the build right around the price range of a Specialized Epic HT (11.3 kg / US$2,800), Canyon Exceed CF 7 (10.55 kg / US$3,300) and Trek Procaliber 9.6 (11.34 kg / US$2,800).
When the pedals came in, the bike weighed a total of 8.18 kg – lighter than most top-end built models. All with bolt-on specs and no DIY tuning or Dremel. Considering I used a third-tier shift kit, brakes and pedals, I’m very happy with this outcome.
See below for a full breakdown of the build (note: “LBS” means the part was bought at a local bike shop; “OBS” means it was bought from an online retailer).
|Frame||Unbranded FM199-SL 29, custom painted ‘Cool Grey 9C’, size 15.5||518||New||AliExpress|
|Fork||Fox 32 Factory Series, Boost 110 x 15 mm, Top-Cap Lever||740||New||LBS|
|Handlebars||MCFK MTB Flatbar, 680 mm||NA||From old build (sawed ends to 660 mm)||NA|
|Grips||Supacaz Siliconex MTB Grips||10.5||New||OBS|
|Stem||Uno6 17 / 70 mm||30||New||eBay|
|Seatpost||Unbranded Carbon Seatpost, 0 Offset, 31.6 mm||NA||From old build||NA|
|Saddle||Berk Lupina Padded Grey||NA||From old build||NA|
|Brakes||Magura MT4 Disc Brake Set||132||New||OBS|
|Rotors||Ashima Airotors 160 mm||30||New||Ebay|
|Shifters||SRAM GX Eagle 12-speed Grip Shifters||40||New||OBS|
|Derailleur||SRAM GX Eagle rear derailleur||98||New||OBS|
|Cassette||Leonardi Racing General Lee 9/48 XD cassette, black orange||220||New||OBS|
|Pulley cage||Leonardi Racing Leo SRAM inner plate, orange||20||New||OBS|
|Crankset||Raceface Next SL Crankset, 175 mm GXP, Blackspire Cinch 10-48T||352||Bought used||NA|
|Bottom bracket||Raceface Cinch BB92 Bottom Bracket||38||New||OBS|
|Pedals||Crankbrothers Eggbeater 1||NA||From old build||NA|
|Wheelset||Unbranded Assymetric Rims 33 mm, Pillar 1420 Spokes, DR six-bolt hubs||542||New||AliExpress|
|Tires||Continental Cross King, Bernstein Limited 29 x 2.20″||90||New||OBS|
|Miscellaneous||Titanium Bolts, Clarks SL Shift Cables, Elite Vico Carbon Cage||NA||NA||NA|
Which brings us to the following question: why would you build a bike this way? If you want to ride a unique bike and not bump into a couple of similar models out on the bike park but also don’t want to spend a princely sum for the high-end models, then having a bit of patience and resourcefulness is the way to go.
To critique, the brake hoses and cables could have been tidier and the frame finish gloss instead of matte so it’s easier to manage the scratches. And I need to get a matte finish seatpost. I will also lookout for the durability of the carbon rims.
So far I’ve found the bike to be nimble and quick to react – probably thanks to the 69.5º head angle and shorter 425 mm chainstays – and stable on the downhills whether on dirt or on the road. In the past I’ve always put 2.0 or 2.1″ tires on my MTBs but this time, with a slightly larger diameter, plus the solid fork, this build is more capable on the new bike park trails. I assume a very experienced rider would have loads of fun on this!
With the very low weight it obviously climbs just like a road bike, so the small little hills around old villages are no problem, neither are long climbs up to the Big Buddha.