Double sided bolt on fixed hub

[Chris N]

Built a Pompetamine up just after Christmas with a bolt on Velosolo cog on the disc mount of my SS 29er wheels, but this means that a) I can't run a back brake and 2) my 29er doesn't have any wheels.  There are only two solutions out there that I can see for fixed disc hubs - Phil Wood or Surly and both are over £100.  I also really like the bolt on cogs, so decided to make my own:





Some big chunks of aluminium:


It only exists on CAD at the moment, but I've done some rough 2D drawings and ordered the bearings and seals and hope to start making it next week.

[Jurek]

Nice dwg.
Be interested to see how this goes.

[Chris N]

And me. Not machined anything this complex since uni.  Might take me a while, need to make some tools and fixtures first.

[yoav]

Your project does look interesting, always impressed by a man with his own lathe

But be honest, making this is going to cost you a lot more than £100, in sweat if not hard cash. Still, let us know how you get on.

[Chris N]

Belongs to work, not me:


It'll cost around £45 in materials but will take hours to make.

[Chris N]

Bearings and seals:

[Pickled Onion]

Maybe it's the way I'm reading those drawings, but how are you going to get the bearings out?

[Chris N]

Slide the axle out after removing one of the end caps and push the central bearing spacer tube to one side.  Then I can use a long drift to tap out one bearing using the inner race.  Then turn the hub over and go at it from the other side.  Also the ID of the hub shell (between the flanges) is a little bigger than the ID of the outer bearing races so you can tap the outer races out with a long thin punch.

[Pickled Onion]

Ah clever!

[air dancer]

How about integrating the inner-race spacer sleeve into the axle and then the axle would also become the drift?

Less components, stronger axle, less faff changing bearings.

[Jurek]

Neat idea.

[Chris N]

How about integrating the inner-race spacer sleeve into the axle and then the axle would also become the drift?

Less components, stronger axle, less faff changing bearings.

I did think about that, but it's a little harder to make and with a separate spacer I can vary the preload on the bearings to remove play by making the spacer shorter (or longer if I make a new one).

In production though, that's definitely what you'd do.

[Ian H]

I'm wondering about the strength of the flanges, given that machined ally tends to be more susceptible to cracking than is forged. Unless Al alloys have improved since I last looked.

[greenmeansgo]

Third option from DMR at half the cost of the others

[Chris N]

Third option from DMR at half the cost of the others

Go on then, explain how I get a 6 bolt disc and a 6 bolt cog on there.

[jsabine]

Long bolts, spacers, and either L/H drive or R/H braking.

You mean you hadn't thought of that?

[greenmeansgo]

Ah yes, on re-reading the thread title it doesn't fit your bill! Whoops!

It is a far easier solution though, but I can see that's not the name of the game here! I look forward to following your project!

[Chris N]

I'm wondering about the strength of the flanges, given that machined ally tends to be more susceptible to cracking than is forged. Unless Al alloys have improved since I last looked.

It'll be made from 6082-T6 (old BS ref HE30) which is a common grade used for machining that is reasonably strong.  You made me think about the flanges though - I measured a couple in the shed and have increased the thickness from 2.5mm to 3mm.  I will need to carefully chamfer the edges of the spoke holes to clear the heads and elbows.

[air dancer]

I like the decent external seals.

Someone ought to do similar as a retrofit kit for existing hubs.

[iddu]

Third option from DMR at half the cost of the others

Go on then, explain how I get a 6 bolt disc and a 6 bolt cog on there.

http://www.broakland.com/dixie.html

[greenmeansgo]

Like it! I now remember seeing something like this previously!

[Hot Flatus]

The path of homemade bike bits ends in extra long nose hair, and a faded hi-viz helmet cover.

You have been warned.

[Chris N]

Thought I'd practice on the easy stuff first - axle and bearing spacer done:


Looks like this when assembled:


End caps and hub shell next.

The path of homemade bike bits ends in extra long nose hair, and a faded hi-viz helmet cover.

You have been warned.

I can see some kind of custom map holder in the not too distant future.

[jsabine]

The path of homemade bike bits ends in extra long nose hair, and a faded hi-viz helmet cover.

You have been warned.

I can see some kind of custom map holder in the not too distant future.

Are you taking orders yet?

[Chris N]

Oh, it's not the sort of thing you can just buy.