Tiny Gravel Bike Protoype

@Neuhaus_Metalworks and I finished up a gravel prototype last month and dumped it down south in San Diego for some testing.

Whenever we approach a new bike, I like to design and test a prototype of the smallest size to develop my knowledge and intuition. I have said this many times before, but it’s worth re-iterating: 25% of the population is under 5’4.


I wanted to make this bike as small as possible and address the pifalls of production bikes:

  • toe overlap
  • too big
  • steep STA

I am slowly honing in on 3D printed FM designs:

Wheelsize: 650x40c

To minimize toe overlap and wheel flop, we choose to go with 650b wheels. We also wanted to keep the bike solidly in the sporty gravel/allroad category. The bike is designed around 650x40c tires.

Fork: No6 Road fork

We chose the No6 road fork for a few reasons:

  • It has a low A2C and clears 650x42c tires
  • It is tested and rated for gravel
  • It is available in multiple offsets


The Good:

  • The reach was spot on
  • There was no toe overlap!
  • Both riders commented on how nimble and sporty the bike felt. I attribute that to the short trail (73mm) and the smaller wheel and tire size
  • The bike was very comfortable. The large amount of exposed seatpost allowed me to flex the seat several MM with my body weight.

The Bad:

  • I undershot the stack by quite a bit. Dana and Karlene are the same height, but Karlene rides with 30mm taller saddle height (crazy!). A 110mm HT would be a better balance between the two riders.
    • with a taller HT, the reach would probably need to be even shorter at 460mm
  • I am really bummed the limited edition GRX groupset does not have 165mm cranks
  • 3D printed Flatmount:
    • I need to add more horizontal tolerance to the FM slots to be safe
    • We need to mask the bottom of the FM bosses during paint. Powder eats up a bunch of space.

We left the bike down in SD so people can get more ride time.


The smiles say it all!


That is super cool! I built a similar bike to this in 2015 for a small women, 5’0’’ if I recall. She was amazed to find such a nice fitting and balanced bike back then and she brought it back last week for a tune up, she is still in love with it. It is built with 26’’ wheels to avoid toe overlap and hydro brakes made a big difference for her too.


love it! I think wound-up forks look great on steel bikes. After we built up our prototype, I’m convinced the 650b/26 is the way to go for ~5’4 and below for gravel bikes. It fits so much better. I have a hard time trying not to project my wheel size insecurities on others :sweat_smile:


Surely you mean 650-40b tyres? Looks fantastic though. Makes you wonder why the big manufacturers (and even the small ones) can’t get smaller sizes consistently right…

I always feel that a very small or very large bike is much more likely to be “right” if it doesn’t look very small or very large until you put someone of the wrong height on it (then it might just look like a cartoon).


Looks awesome, I’m a big fan of the proportional wheel philosophy.
I made something similar for the lady, although yours looks much nicer of course.

I used the last version of the mechanical+disc ultegra group. Got a set of 165 cranks too and the work a treat.

I too undershot the stack. Aimed to have room to go lower if the bike ended up being used as a roadie but the fit stayed the same and the bike keeps off road mostly.


These old Georgena Terry videos were very enlightening for me:

There are four total.

Additionally, the Georgena Terry Cobra interview, and the Path Less Pedaled one as well.

My partner is 5’4", but we have the same 30" inseam. It’s been really interesting seeing the bikes she has progressed through. Old Specialized Sequoia (with the zerts inserts) 700x35mm tires, to a Marinoni road bike with 700x25mm tires, to the current drop bar bike that I’ve made for her with 650b x 48mm tires.