Bike Design with Crayons

We just learned about the 2023 Marin Gestalt X10. A $1,549.00 bike that is almost worth riding.

I try to rep Marin County with my bike work. It’s an incredible place to ride, especially if you want mixed terrain. We have hundreds of miles of gorgeous fire roads and a ton of singletrack from mild to wild. When a bike has the name of this county on it, it should be taken seriously. The bike should be sick. This bike isn’t.

Don’t take this post wrong, there are few bikes in this price range that have as much potential for an entry level rider. What I am going to explain is that for almost exactly $0.00 more money, this bike could have been a high value bike that the market could really use. A cheap bike to challenge bikes 7x the cost.

This is decent bike for an entry level rider. A total train wreck when taken seriously.

I took the time to translate that geometry gibberish into something meaningful that we can all understand. Below is a BikeCAD sketch of a large framed bike. The yellow highlight values are those provided or implied by the marketing. The other dimensions I added as if I were setting this bike up for myself. For reference, I’m 5’10” tall and tend to not use drop bars.

To call the seat tube on this bike a tragedy is an understatement. Certainly, the ‘designer’ doesn’t have much experience or understanding with bike design. By effectively chopping the tube short, very little seat post insertion is possible. Combined with the idiotic choice of a 27.2mm pin, the user is left to use only very low quality short travel dropper posts. I drew this with a 125mm dropper but I’m being very charitable. IRL, I’d expect to have to use a 100mm junk dropper.

Why? This was an expensive and time consuming choice, making a tube like this. What was served by shaping the tube as they did? Nothing good, all bad.

Below, I show the difference that can be had when the basics of bicycle design are understood.

    1. 31.6mm seat pin. A 27.2mm post can still be used with a shim if desired. More, high quality dropper posts can be used.
    2. Shorten the seat tube to 450mm. This gives enough room for an average real world dropper stroke to be used. Here, 210mm.
    3. Slacken seat tube 1.3 degrees to 72.7 degrees.
    4. Offset seat tube 15.2mm at the bottom bracket.
    5. Bend the seat tube 10 degrees at the very bottom.

That’s really not much to change. Visually, the bike looks better. The frame is cheaper, easier, and quicker to make. The user is able to have a wide choice of quality droppers to use. This is OBVIOUS! Producing the bike as they did is simply stupid.

We then look to the front of the bike. A 710mm front center is about as much as is going to be had when using commodity drop bars and stems. A slightly longer head tube make help open up stem choices and reduce spacer count.

The problem now is that there is a divergence in ‘what a gravel bike is’, even in popular uses. Some won’t consider anything but drop bars. Others, looking for much higher off-road performance, are moving to flat bars. Those are two different frames.

Below, I show the OEM frame with SQ Labs 30x 16 degree bars on it. This would be my choice for setup in this case.

The problem here is obvious, I’m forced to use a 120mm stem to fit the bike because the front end is designed for use with drop bars. This means that, in the dirt, the bike is slow and sketchy because of a compromised design.

What if Marin chose to break up the bike to two frame types? A drop bar frame and a flat bar frame. This isn’t as crazy as it sounds. This is a very cheap aluminum frame. Having two types is hardly a hardship outside of inventory needs. What they get is the ability to sell a very high performing flat bar bike. This is the bike people should be buying. Provide that.

In addition to the previous changes to the seat tube:

  1. Extend the front center to 775mm
  2. Increase the head tube length to 185mm

There you go. Two frames that Marin COULD have made….but didn’t…because they didn’t hire an actual bike designer. I wasn’t trying to push my idea of cutting edge design here. Just do the very basics changing as little as needed. Much more could be done (like bringing the rear center to 410mm).

PS. I honestly think that Marin was trying to copy my 2018 Bird of Prey, without understanding it. Lesson, don’t copy what you don’t understand.

For reference, here is a print of the stock XL Gestalt X10