Hello Guys!
Some time ago I realized that it’s already ten years since I sent a first message to the local framebuilder asking for a possibility of taking a course at his workshop. Long story short - I didn’t take the class, but since then I spent countless hours thinking of design, tools and fabrication of frames. However, not a single build was made by me until now, so I decided that I should finally start now.
This topic was created to document my idea, design and finally: fabrication of my first build.
So let’s start!
Chapter 1: Idea
I want minimal number of bikes that cover most of my needs. By minimal I mean only one bike.
I used to have lots of them and after initial excitement of purchasing the next rig, I realized it’s not for me. Most of them ended gathering dust, partially disassembled, none of them fully working, taking my physical and mental space.
I spent last few months selling them, getting rid of unnecessary parts and settling with 2 for now:
Vintage touring bike, which is used 95% of time to commute or just ride along when time allows and modern steel hardtail, which is lovely on steep, technical trails, but for my neighborhood feels a bit overkill, since my local offroad routes are mostly gravel and flat, easy singletracks.
So I still feel bad for my mountain bike sitting alone and unused in my garage and think of reducing to only one bike, but having only a drop bar all-road bike doesn’t appeal to me, so I came up with the idea of designing a bicycle that would cover as wide range of applications as possible and keeping it as my only one if it happens to be as good as I think of it.
And finally, I want to build a bike myself!
Chapter 2: Guidelines
Application: the bike has to work for me primarily as a commuter, since it’s 90% of my riding time for now. Other than that, I want it to allow me to have fun on a pump track while going back home from my workplace, do the groceries, and handle offroad well enough, so I can ride with my enduro buddies that one time a year, that we can finally meet. That’s a lot to have from one single rig.
Other than that, I want it to be simple, easy to maintain and be versatile in a particular way. Not like a complicated multitool with 74 interchangeable attachments. More like your favorite shoes that are so comfy, that you use them every day for every possible occasion.
I spent quite some time looking for similar bikes in the web. Most of them turned out to be rigid mtbs, often singlespeed, which, once you are aware that you want something somewhat good enough in every field instead of specific purpose tool, seemed to made their owners really happy with them.
Most appealing to me were bikes like Kona Unit and Stridsland Beachcomber with their simple look and adventure readiness. However, the second one is non-suspension corrected which I found limiting in terms of offroad capability, so the Unit became some kind of a baseline for this project.
So it’s time to turn my wishlist and inspiration into some specifis requirements and constraints:
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Robust - steel frame
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Easy maintenance - outer cable routing, most popular standards with variety of parts available:
BSA73 mm , UDH, 44 mm head tube, ISO/PM brake mounts - yet to be decided. -
Commute friendly - full fender mounts, dynamo wiring, luggage space - head tube mounts for the front rack
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Pumptrackability - some kind of nimbleness, not so long wheelbase, bombproofness, stepover clearance
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Offroad - rather long wheelbase (need to find compromise), dropper post compatibility, 29 inch wheels for the best availability of tires and rims.Boost axles. Suspension-corrected geometry allowing for 120-130 mm fork. Default setup full rigid.
Chapter 3: Geometry
The initial geometry layout became more or less obvious as soon as I choose tire size, intended purpose and measured my fit from currently used bikes.
Middle of the road tire size of 29x2.3-2.4 offers lots of models ranging from slick to trail tires and we take it as our primary size.
Being 6 ft/183 cm high with inseam length of 86 cm I am in the “Large” size area most of times, so I checked geometry tables of similar bikes such as Unit, Nordest Sardinha, Surly KM and compared it with my current mtb.
The initial values are:
Reach: 640 mm
Stack: 465 mm
WB: ~1180 mm
CS: 430 - 435 mm
FC: ~750 mm
BBH: 315 mm
BBD: 60 mm
ST: 460 mm
STA: 74°
ETT: 640 - 650 mm
HTA: 67-68°
ATC: ~510 mm
FO:51 mm
Now I have to go to the drawing board and make sure chainring and tire clearance will be enough with those numbers.
Please, stay tuned for CAD drawings and progress logs.
Let me know, what you think!
Regards,
Bartek