Geometry critique

As a complete novice I was wondering if anyone could see some glaring mistakes in this proposed frame. I think I’ve included the neccesary dimensions at this stage in the process, including my own geometry (using PVD/RAD method) to give some context about my position on the bike. I have the means to fabricate a custom stem to get the fit right.

Bike Geo.pdf (46.4 KB)

PVD-RAD.pdf (38.4 KB)

Use case

Despite an aesthetic preference for mountain bikes, this will predominantly be ridden on road or on mild singletrack when bike touring. Given my space constraints this really has to be a do-everything bike and i’m aware that it will have to compromise in a number of areas to achieve that.

Parts pref.

  • I designed this frame around the eXotic 110mm Boost Fork
  • I plan on using a flat bar
  • I can make my own stem but would prefer to buy it. I think the current length of the head tube will make this difficult
  • 29"
  • 175mm cranks

I also thought it might be cool to have a dedicated thread where novices could show prints of their proposed builds for critique, but as a novice myself i’m not so sure what the desired criteria for a print really is to make this worthwhile.

This drawing was made using @Daniel_Y fusion 360 tutorial so big thanks to him.


That reach is Haute Catagorie. You may have difficulty finding tubing that long and would probably want to run your stem backwards if that seattube length is correct. The CS length is quite short, you may need a special yoke depending on material, tire and chainring choices. 69* is steep for a 490mm crown to axle and 56mm is a lot of BB drop. This design pushes the envelope!

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If you’re mostly going to ride road and gravel why the huge reach/shortish chainstays? Weight balance is going to be wacky to say the least and it’ll corner terribly if you’re sitting back in the saddle just due to having no weight on the front wheel.

I mean, it looks like a crazy aggro mountain bike that someone misprinted the 63 degree HTA as 69 on.

IMO it will be the worst of both worlds when it comes to riding both gravel and mountain bike terrain. Long and unwieldy but not particularly confidence inspiring when pointed downhill.



As someone who lives in Moab and West Yorkshire, I think Wiz is up to some British mocking of these digital tools, but I’m sure he’d get better results if he just kept saying “longer, slacker” to ChatGPT. :rofl:

Is this intended to be a handlebars behind the steering axis bike?

To be honest I saw PVD’s 2021 X1 all road bike and took quite a lot of inspiration from that. Choosing to dial back the FC a bit as I’m currently riding 690… the RC I increased a bit because I’m tall and I believe STA and HTA are ripped directly from PVD’s bike. Im not trying to take on road racers, I just want to do wheelies and bop off of curbs. Maybe ride it in the woods every now and then. Would you suggest reducing the Front Center?

I mean if this was the right geo (which I’m getting the impression, it is not) then yeah I have no issue running a stem backwards. From what I understand it affects steering very little

Also English and also lived in Moab! Worked a brief stint at Milts.

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I’d say go for it. Who cares what people think. If it sucks to ride you learned some valuable lessons for the next build. If you love riding it, then great news. Tell us either way.


Best answer yet! Only one way to find out if it’s truly the bike of the future!

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When I design a bike from scratch, I decouple the fitting geometry from the handling geometry.


In general, I think PVD and Lee’s RAD is a great framework for quantifying and measuring and fit across your own designs. But I would be careful applying their recommendations to your own personal fit.

The RAD method biases towards standing descending geometry and forces you onto a steeper STA, which can cause wrist and patela (knee cap) pain in some people. For hardtails, I tend to weigh seated climbing fit over descending fit which results in a slacker STA and longer chainstays. This leads to a less-than-ideal standing reach. However, I welcome that tradeoff because I want my hardtails to be endurance mountain bikes.

If this is the case, I would look at your seated geometry first and compare that to your RAD fit.


Also, a strawbale builder. :rofl: It would help to know your height. The seattube length and reach are out of proportion. If you’re really tall (6’4"-8") you might find a reach of 550mm about right with a short stem, but there are very few options for the 450mm + seatpost that you will need for that 370mm seattube. If that seattube works for your height (5’4"-8"), then that reach, or even 550mm, will position you like superman.

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I think what you need to remember is that Pete gets SUPER EXCITED ABOUT STUFF and goes way overboard with it and then years later gets excited about something else and changes his mind.

He’s a great guy but he’s a terrible guru and there’s no need to follow him down whatever his rabbit hole d’jour is. Riding easy trails and gravel is something people have been doing for a LONG time (150+ years) and you don’t need to do anything crazy to build a fun bike for those conditions. You’d be better off copying a Roubaix or something than copying Pete, honestly.

But yes, some basic info about you/your height and weight and such would help.

To be clear: you should build what you want! If it’s not perfect, that’s ok! You’ll have fun building it and fun riding it and there will probably be things you want to change for iteration #2 regardless. Don’t let a bunch of internet dorks ruin your plan if you’re excited about it!



I agree with Walt. Be careful about what Pete preaches. I subscribe to his basic idea but have deviated in a few key areas and ended up with bikes sthat ride great. Honestly, pick a bike you like the look of and copy the geo with maybe a tweak and see how it goes…or as said above build your design and see what kind of bike it gives you. Use the exercise to learn how to build bikes and mess around with it.



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Community rebuilds?? I was there from feb 2019. Small world if so.

Haha I feel like I’m slowly being deprogrammed. I really appreciate the encouragement from everyone to just give it a go but for my first bike (and in general) I think I really need a win. I’m going to go back to the computer screen and implement the wisdom here.

I’ll take a look at my seated geometry on my current bike, far from a perfect fit but the best I’ve been able to do with what I’ve got, and then go from there.

For ref. I’m 6”3/190.5cm and weigh about 75kg

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Yo love the idea of this thread. Figured I’d share this as I had a bike built to a similar brief in 2020 — off-road/tourer that would do double duty as my primary MTB. This was the initial drawing I sent the builder (Darren Larkin AKA Larkin Cycles, based in LA at the time). For reference I’m 183cm (6’0) with a 89cm (35") PBH — all legs and no torso.

The final design changed based on some feedback Darren had but it was similar enough in the end. A few thoughts on the bike after 2 years of riding it.

  • Seat tube could be a touch steeper for a dedicated trail bike but 73° deg seems to be where I’m happiest on longer rides. I agree that the best thing to do is find a bike you like to ride seated and base the rear end off that. A little steeper will be fine but I wouldn’t go all out there. If you’re touring on it you will be sitting for most of the ride.
  • The HTA is perfect (final design was updated to be 67° sagged, shown above at 67° static), I wouldn’t want the bike to be any steeper. Currently riding it with a Helm Coil, 44mm offset, 140mm travel.
  • I went with Paragon Sliders and have ended up with the stays at around 450mm. I played around with them a bit when I first built the bike and can’t really notice any difference in handling with the stays 10mm shorter so went with the extra mud clearance.
  • 50mm ish BB drop seems about right for a 29er, I rarely get any pedal strike and can get pretty lazy with my feeting when I’m tired.
  • The bike has a very high hand position and that makes a huge difference to me for longer rides. I’m using 37mm rise bars with 15° backsweep (Hunter Smooth Moves).
  • A long headtube is great. It makes for significantly larger framebag space than I’ve seen on equivalent bikes. I can fit my tent w/ poles, all tools/spares/pump and a 3L water bladder in my framebag and still have room in the front triangle for a 800mL bottle mounted to the seat tube.
  • If you plan to tour on it defo add some kinda rear rack mounts. In my experience a rack is far better way to carry gear than any seatpost mounted bag. Especially if you throw a dropper into the mix.

Photo below of the bike fully loaded for a 3-day / 200ish mile ride we did early last year. 40% sealed, 40% gravel, 20% rough 4x4 roads/singletrack. Yes it’s a compromised design but I would say I’m 90% happy with where it’s at considering what I set out after. Good luck with the project and post us some updates!

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I am 6’3" and have played around a bunch with long reach/long effective reach (reach +stem). 3 of my dual suspension MTBs have reaches greater than 500mm, one is 530mm, with effective reaches all around 580mm. I can’t see going much longer, as the bikes, especially the 530mm, feel noticeably sluggish and less maneuverable until they get going 15+mph. You will need a longer seattube for your height/leg length, probably north of 450mm, or you will have to get a special seatpost.


In the '90s, for private residences around Moab/Four corners.