Shaft Drive Klunker bike

BartRidesEternal · Sep 27, 2024

Hey Ratters,

I'm working towards my first completely scratch built bike.
And I thought; Lets share the whole process!

At the moment I am working on setting up and arranging my workshop, since I'm slowly working towards building frames for customers.

Regarding this bike I had in mind: I have five brand new shaft drives in boxes. Three 'singlespeeds' or 'three speeds' and two with an threaded rear sprocket.

Two types: Right is for regular hubs like the Shimano CB-E110 or Nexus 3.

At the moment I am doing lots of inquiry! Measuring, calculating and looking for good mountainbiking geometries.

The shaft drives 'chainstay length' is fixed, so that is why I can't build a long chainstay (belly mounted BB) cruiser with this.

Right now I am figuring out the measurements of this shaft and how I build a durable frame with this.

Unfortunately VERY fat tires won't fit, probably a maximum of 2 inches, depending on wheelsize.... which is dependant on the internal gear ratio....

Measuring the dropout width.

BB shell.

My sketch of the bike.
A looptail, shaft driven klunker bike :inlove:

I intend to use CroMo tubing.

BartRidesEternal · Sep 27, 2024

Little update:

I checked the intended dropout width in multiple ways: In my alignment jig and by assembling/adjusting the rear hub.

Shimano CB-E110 hub.

I also checked the Ratio: 1:2
1x crank turn = 2x wheel turning.

Tire clearance is meh. We'll see what we can do with that.

Pondo · Sep 27, 2024

Pretty cool! This will be a fun project.

BartRidesEternal · Oct 1, 2024

Bottom bracket shell is machined. Only a section to be removed that has to be milled:

This is how the bottombracket shell looks in the BRIK bikes (a Dutch brand that sells bikes with shafts).

Youtube video link

Since the 'open section' of the bottom bracket, especially in the corners, has a higher level of stress and tension, I decided to thicken the ends and have that part a lot stiffer.
I purposely designed the open section with a radius, so that tensions do not concentrate too much in a 90 degree sharp angle.

The bottom bracket is a 51,2 inner diameter (almost the same as a US BB) and 57mm outer diameter on the thinner section. The ends are 60mm. So a central wall thickness of 2,9mm :thumbsup:

I don't think this will be a light bike, but then you have more energy downhill

ifitsfreeitsforme · Oct 1, 2024

Neat. I've wanted a shaft drive bike for twenty plus years.

Are you designing with Creo?

BartRidesEternal · Oct 3, 2024

ifitsfreeitsforme said:
Neat. I've wanted a shaft drive bike for twenty plus years.

Are you designing with Creo?

Well, I might be open to selling a frame/bike when its done

I am indeed designing with Creo Parametric! How did you recognize it? Solid Works is common too :thumbsup:

ifitsfreeitsforme · Oct 3, 2024

I could tell by the font. I use Creo at my job (senior drafter at Colt).

BartRidesEternal · Oct 3, 2024

ifitsfreeitsforme said:
I could tell by the font. I use Creo at my job (senior drafter at Colt).

Very cool! At my employer, we work with Creo Parametric and the Windchill system for drawing data storage.
In general, it works really good. I can even work from home and log in to a virtual desktop (the machine at my work does the heavy lifting then).

Shells are done, but I think I need to check the inside angles again and remove a bit more:

No problem ironing that out. You can see the gaps and the shell that can go more to the right.

CroMo tubing is here too!

Working on a geometry sketch.

Seat tube will be 28mm.
Chain- and seatstays 15mm.
Downtube 35mm.
Top tube(s) 28mm.

I'm preparing the bender for a 15mm loopytail.

The next days I will have a lot to do:
Saturday I'm enjoying a day at the Dutch mountainbike museum (800 bikes!).

Monday I will attend brazing class.
Looking forward to this!

ifitsfreeitsforme · Oct 4, 2024

Windchill... my boss calls it "Windshield". We laugh every time.

SwissGuy · Oct 4, 2024

BartRidesEternal said:
Dutch mountainbike museum

I just can't wrap my mind around the fact, that the Netherlands as the very definition of a flat country has a MOUNTAINbike museum...

BartRidesEternal · Oct 6, 2024

SwissGuy said:
I just can't wrap my mind around the fact, that the Netherlands as the very definition of a flat country has a MOUNTAINbike museum...

What should it be called then?
FLATainbikemuseum :thumbsup:

The Dutch always are excited about something they don't have

I will post pictures of some of the 800/900 bikes they have in a thread here on RRB soon. It will be picture heavy then!

In relation to this topic:
Look what I found in the museum:

B1 bicycle. 26". They use these in a dusty mine since a chain gets dirty fast.

Seeing that last picture. It seems that its (the BB) welded first and then machined for the shaft protruding from the frame when assembled.
Also little tire clearance.

BartRidesEternal · Oct 6, 2024

At the mountainbike museum I met a guy who is also enthousiastic about Klunker bikes. We met via a Dutch marketplace and he saw one of my project on RRB's I believe. We decided to meet at the museum and ride

He also met Paul from Atomic cycles last year. Incredibly cool.
We had fun and he seems a great guy. We'll probably ride again!

This was his ride:

1952 Schwinn Hornet with Araya's and a Shimano CB-E110 coasterbrake. Beautiful to see it on the mountainbiking trails :inlove:

Pondo · Oct 6, 2024

BartRidesEternal said:
Saturday I'm enjoying a day at the Dutch mountainbike museum (800 bikes!).

Oh, I'm jealous! That sounds awesome!

moleman · Oct 10, 2024

Super interesting! I wonder, how difficult would it be to widen the bottom bracket? Like, a longer BB axle and an outboard left side bearing? That might allow for wider tires....

BartRidesEternal · Oct 15, 2024

moleman said:
Super interesting! I wonder, how difficult would it be to widen the bottom bracket? Like, a longer BB axle and an outboard left side bearing? That might allow for wider tires....

I thought that too!
Well, the gearing has a certain angle to allow the shaft to move 'outwards' to the dropout width.
I don't know, what will happen when I change that angle (I need new housing for the bearings and, such).
Also the BB width will change. Which, all in all, might pose quite a challenge.

But I do have more shafts (sets) lying in my shack, so I can experiment with another bike.
Maybe even fabricate a bike with open bearings (sealed industrial) and open shaft. :crazy2:

I've got plenty of ideas!

My bottom bracket shells (2x) are done and fit perfectly! (pictures below)
Now I can concentrate on the geometry of the Klunker bike and start with tube bending/notching and such.
First I need to re-arrange my shed, since bike building and bending stuff requires space :thumbsup:

If anyone has a great geometry suggestion, I'm open to it and exploring.

BartRidesEternal · Oct 15, 2024

Is this XL geometry interesting perhaps?
I will compare it to my current klunker, which I like but has a little bit short top tube.
The chainstay is obviously fixed on this shaft drive (445mm).

Shaft Drive Klunker bike

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