Bottom bracket

The bottom bracket is the heaviest part of any bike. No wonder since it needs to be the strongest. Don't be surprised if your first attempts result in some squeaking noises while pedaling. Something I really hate. The aluminum tubes make it even louder. But both methods described below should work pretty good.

It is essential to have an adjustable bottom bracket. Yes it is possible to adjust the length with the seat only. But the riders weight will shift accordingly. Ideally you can tweak both.   


Plain bottom bracket shell.
After looking at Rich Richardson's Raptor trike I finally figured this one out.
The two side plates are higher then the boom or the bottom bracket shell won't fit inside with the exhaust clamps. So they stick out on the top by half an inch or so when using 50x50mm tubes for the frame.

If you were to cut the main tube all the way back to your size, the bottom bracket shell could be in the middle. The sliding boom extends far enough to adjust.

But if you keep the main tube longer the bb assembly can be shorter while sliding over the tube. I preferred a longer main tube in case I want to attach a fairing. This means the bb shell and clamps need to clear the main tube.     







Derailleur post.


Suspension BB shell






5 comments:

  1. This comment has been removed by the author.

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    1. I never replied!

      I had no problems with the BB despite the threads facing the wrong side. In fact if you have the threads the conventional way, one would expect the cups to come loose when you pedal. But they don't. I guess it doesn't matter that much.

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  2. Is this setup possible with a single speed crankset?

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    1. You can have as many gears as you want. A single gear. Or 3X3X10=90 gears with triple, mid frame gears, and rear. Or 270 with all of that plus an internal hub. But basically you only put gears on you need. Modern mountainbikes have single cranksets and a wide range 11-36 or so cassette. Use what you have. Build cheap.

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