Belt and chain custom frame build thread

[Papa]

I don’t know what u mean by HAZ coloring

The HAZ, or Heat-Affected Zone, is the area of the base metal (adjacent to the weld) which is not molten, but has had its micro-structure and properties altered by the intense heat from welding.



Apparently, it was the clear coat giving me the false impression the frame was titanium. My error.

 

[Hummina Shadeeba]

700$ for the hardtail above. It needs bearings replaced in the motor and jackshaft as it’s getting noisy but otherwise runs great and my daily commuter.


I had more frames made. A bit longer and stiffer around the bb and conical headtube n nice steel fork. If u want one i have an extra.


Making a full suspension frame I don’t trust having the pivot point behind the bb is good enough and maybe the chain will drop. It’s the norm on motorcycles but bikes always use a chain tensioner. And this rigid bike is good enough and moving on.

Had a psu mold printed for making the batteries and moving on to ion cells and a smart bms.

 

[Hummina Shadeeba]

A swing arm concentric with the bb isn’t ideal for a pedal bike and causes bobbing when u pedal but for simplifying a rear suspension on this bike it’s ideal

There are only two places making concentric pivot bikes for a single speed

The first I still don’t understand exactly what or why they do what they do:

Digit Datum — Digit Bikes

Trail Bike MTB Mountain Bike Made in USA

www.digitbikes.com

And the starling bike:

https://www.starlingcycles.com/frames/beady-little-eye-2024/

They would sell me the rear for like 1400$ and I’m not doing it because of the cost and I’m not sure if I like their design and wondering what you think of it and my possible alternative.
The explanation of how they do it starts at 3:00

Instead of adding a separate extended threaded part to support the bearing, as they do, why not just get bb shells made that have the correct outer diameter to act as shafts for the bearings? The bb shell diameter just would need to be accurate and with a slight lip at the inside ends to stop it going too far in. The bottom bracket would hold the two bearings in the same as with the starling bike.

 

[Hummina Shadeeba]

I want to get this frame made but wondering if the squat will be horrendous. What you think/know? It will use 70 and 22 tooth chainrings with a rear suspension pivot point concentric with the bb and driving sprocket, and use a typical bicycle swingarm length.


I can’t find the source here on the forum or on the web, so tell me if I’m wrong, but I think I remember in a race through tight cones a bike with its mass vertically-centered will be quicker. This is because the bike pivots at this center of mass when turning and moving mass closer to this pivot point means the mass has less distance to travel when turning so quicker. This seems a rare understanding though and often the only reason stated to raise mass on a moto gp bike is for clearance.

 

[Hummina Shadeeba]

Selling this for 600$ message me.