Custom Rear Hub Assby -LHS FW sprocket + retained disc brake

boostjuice

10 kW
Joined
Jul 27, 2008
Messages
969
Location
Canberra, Australia
So as part of my ongoing Goldenmotor HPM5000B build I decided I wanted my drivetrain to incorporate a LHS drive, freewheel isolated sprocket whilst retaining my rear disc brake.

Being that my donor frame has 150x12mm dropouts (2008 Mongoose Black Diamond Double) I figured with a bit of custom fabrication I had the lateral real-estate to squeeze in these features using a spare 48H 135mm spaced hub that I had laying around adapted to 150mm spacing (a standard rear Modus hub as equipped on Yuba Mundo's). After a lot of thinking about the design I came up with the following. I wanted to minimise custom machining, so I modified off-the-shelf components wherever possible.

All parts were machined on an ancient manual mill with a rotary table, angular indexing and a slotting attachment (Deckel FP1)

Modifed parts included:

2x Gusset Double Six Single Speed Sprockets
Hope Pro 2 Steel Freehub Body
IS to post mount Hayes 160mm rear disc adaptor
#41 72T Alluminium sprocket
ACS Crossfire FW with Custom BCD flanged outer

The bearing pockets in my hub were also deepened to allow an extra bearing per side to be installed over the standard two. The disc brake flange was also narrowed a few mm as well to increase available space to the bolt on freehub body.

For the axle I used a length of 15mmOD/12mmID seamless SS-316L tube which fits the 6902RS bearings used by the hub whilst also being a matching fit for the 12mm through axle (skewer).

Maybe these pics will help others who want to go down this path and are fortunate enough to gain access to a mill. Any 135mm Disc hub that uses 6902 sized bearings with either a Freehub or screw on cluster should work. I used a Modus hub (screw on freewheel cluster) only because I already had it on hand and it had 48H drillings to allow a strong wheel build. I was eyeing off the White industries M16 Rear hub as an alternative as it also uses 6902 bearings as standard + a regular freehub.

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Jesus H Christ that thing is huge! :shock:

Is the motor going to sit in the frame and drive it with 420 pitch chain or something?
 
Dude, that is some crazy work right there. I went through some of your post history and checked out your bike. That thing is sick!!! I wish you'd post some video. Especially since I have a 2006 Black Diamond Single. Keep it up!
 
Miles said:
Nice work boost. What was your set-up for modifying the Crossfire freewheel?

Perma Grit 6mm Course Tungsten Carbide Spar slotter as recommended by yours truly :mrgreen: mounted in a Deckel FP1 slotting head attachment (indexing done via rotary table). Took a F@*%n age to get through the Crossfire's hardened steel (like 8 hours or so all up). Had to keep cleaning the miniscule amount of filings out every few seconds with compressed air and keep the feed rate very slow and steady or the slotter would come out of parallel and pull the FW out of the chuck on the up-stroke. In hindsight, I wish i had've just sent it to Thud.....

View attachment Deckel_FW_Slotting.mp4

Also, I had to make a hybrid using a standard toothed Crossfire's FW inner mated to memran's custom Crossfire outer bolt-flanged component as he elected ACS to use a more conventional type of removal tool splines without the smaller ID collar needed for the bulk of the spline torque transfer.
 
MD. said:
Dude, that is some crazy work right there. I went through some of your post history and checked out your bike. That thing is sick!!! I wish you'd post some video. Especially since I have a 2006 Black Diamond Single. Keep it up!

Cheers. I ended up cracking the $#!ts with all the power being transferred through deraileur chain (chain guides failing and mangling expensive custom sprockets), so the old drivetrain is now scrapped in favour of a rebuild using the beforementioned 6inch core Axial Flux boat anchor.

Heres a couple of surviving videos of my brother toying around with the previous setup.

View attachment Egoose_Cyclone1.mp4
View attachment Egoose_Cyclone2.mp4


jonescg said:
Jesus H Christ that thing is huge! :shock:

Is the motor going to sit in the frame and drive it with 420 pitch chain or something?

Swing arm mounted motor, close to the pivot point, 9.67:1 fixed 2-stage reduction ratio. 1st stage 22T>65T #219, 2nd stage 22T>72T #41/420. Should top out at ~80kph if Golden motors dyno chart is to be trusted (and get half way up there on 1 wheel only hopefully :mrgreen: ).
 
boostjuice said:
Perma Grit 6mm Course Tungsten Carbide Spar slotter as recommended by yours truly :mrgreen: mounted in a Deckel FP1 slotting head attachment (indexing done via rotary table). Took a F@*%n age to get through the Crossfire's hardened steel (like 8 hours or so all up). Had to keep cleaning the miniscule amount of filings out every few seconds with compressed air and keep the feed rate very slow and steady or the slotter would come out of parallel and pull the FW out of the chuck on the up-stroke.
Crikey! Thanks for the video :)
 
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