The folding bike specialists at Dahon are mostly known for building small wheel, compact commuter bikes, but their new GB-1 breaks that mold. The new aluminum Gravel Bike #1 sizes up to mixed surface friendly 650b Road Plus wheels, yet still folds down into a relatively compact footprint to make it easier to travel to your next adventure ride.
Dahon GB-1 650b folding travel gravel bike
With 650b the GB-1 is set to get the largest wheels in the folding bike maker’s line-up. That’s a big step up for the company that mostly builds 16″ & 20″ wheeled bikes. But with the idea of opening up more freedom to ride on any terrain or road surface, the full size 27.5″ wheeled folding GB-1 opens up a lot more possibilities, whether it means taking up less space at home, or being more compact when traveling by car, bus, or train on your next adventure tour.
Unlike most of their more compact bikes, the GB-1 uses a traditional diamond layout frame that splits in the front triangle. It does feature a dropped toptube with a strut at the seat cluster, a concession to improve standover. That’s so more riders will fit on the bike, as Dahon tends to make their compact folding bikes in a single frame size, making up fit differences in seat and bar adjustment.
We’ll have to wait and see if the single frame size carries over for the production GB-1. Update: Dahon has now confirmed that the GB-1 will get three frame sizes when the bike hits shops later this year, to fit a broad range of gravel adventurers!
The folding front triangle is held in place with the same toothed smoothly integrated LockJaw joint system as their compact Clinch bikes. It looks to share a similar butted aluminum frame construction, with the folding mechanism leaving the rear end unaffected. Geometry-wise we have little info now, other than Dahon calling it “adventure travel inspired”, and promising “loads of tire clearance.” This pre-production bike was seen sporting a set of 27.5 x 1.75″ (42mm) Panaracer Pasela tires with decent clearance, hopefully enough for 47mm tires.
How to fold the GB-1
To break the new GB-1 down for travel, just drop the saddle with its quick release post clamp, fold in the pedals, and unclip the quick release Flatpack stem.
That unique new, open machined Flatpack stem when released allows the road drop handlebar to rotate within its stem clamp, allows the body of the stem to pivot up & down with respect to the steerer, and disengages the body of the stem so it can rotate freely of the steerer tube clap that remains securely clamped. There’s really a lot going on with that stem, pretty much disengaging in every direction with a single quick release clamping mechanism over the face plate!
To fold the frame, the LockJaw joint requires an Allen key to rotate the single locking bolt less than a full rotation in each the top & down tubes, at which point the bike simply pivots on the LockJaw hinge.
A wire loop foot attached at the bottom bracket supports the bike when folded, also protecting the front chainring, and helping the bike to balance upright when folded.
The GB-1 sticks with a number of standard technologies that for the most part have been left behind on premium gravel bikes, but were likely selected to keep costs down, and maybe helping repeated folding for travel remain easy. The bike features quick release axles, a straight steerer fork, a threaded bottom bracket, and Dahon’s easy-to-manage full length external cable routing with housing sliding loosely through the slightly oversized looped cable guides for simple folding.
We’ve seen this prototype built up with a couple of slightly different 1x drivetrains and mechanical disc brakes. But the frame uses a round seatube and looks to have plenty of room around its threaded BB and driveside chainstay to probably fit a double chainring setup as well.
The frame also features rear rack mounts to expand on its mixed-use touring capabilities, and may be able to be set up with full fenders.
The GB-1 as we see it here is still technically being referred to as a prototype by Dahon. That said Dahon claims the bike will be available for purchase in late fall 2018, which suggests design is probably mostly set by now.
Update: The GB-1 has gotten some updated spec around its axles & stem. Check out the updates here.