Im building an omnium inspired cargo bike. I’m about to connect the steerer to the fork.
Since there is no fork underneath the headtube. How do you secure the steerer tube?
I made a “stem” where I braze on a plate for the connector.
Is it better to use the tp part of a headset on the bottom, or do I make a crownrace seat on the steerer tube?
Thank you
Start watching this video from Phil Vandelay’s cargo bike build at the 7:00 minute mark – he constructs the steering mechanism. It might give you some pointers…?
-Jim G
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I did the latter. I just brazed a standard crown race on about 10mm from the bottom of the steerer. Then, I cut some slots in the bottom 10mm to act as a key for the steering linkage plate.
I suppose you could use a top headset, and clamp the linkage to it, but that seems like more work, and takes up more space.
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Omniums use a crown race and bottom cup at the bottom since the steering arm bracket is welded to the bottom of the steerer tube. It’s a rock solid setup so that’s how I would do it. You can also buy an Omnium steerer tube that’s ready to go but we won’t have them back in stock for a few months yet.
If you’re using a clamp on steering arm I guess you could use a top cup upside down. Seems unnecessarily complicate to me though since you don’t need adjustments there to align the bars with the fork.
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I used some 1.125 .035 chromoly tube, welded a crown race and arm like bushtrucker posted. The linkage is 70mm from center (bushtrucker was kind enough to measure the Omnium).
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Thank you all, this was the info I needed
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Finished the task today, I brazed a crownrace seat on the extended steerer and put in a star nut. Should be secured now
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I never bothered to add a crown-race seat. I just used an upper headset on the bottom upside down.
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Here’s another question about building cargo bikes.
The headtube assembly on my fixture can’t get low enough to build a cargo with a one piece downtube, “boom”. But I fixed that problem by buying konga’s flat surface fixture blocks. So next build will be a omnium style corgi with a one piece downtube/ boom thingie.
My question is what tube will do?
I thought a 46mm down headtube. But they don’t come that long.
And a 46mm 4130 tube might be to heavy?
Thanks
We (a friend and I) used a 50,8 mm CrMo (don’t know which steel exactly) tube with a wall thickness of 1,2 mm. Wasn’t very heavy and seems fine so far 
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Thank you, that will the route I go
