Press fit crank vs Dee Jay

[Dee Jay]

disassemble a generic steel cog from a press fitted chainring in 4 easy steps!

hold the chainring/crank up and inspect the crank side like-so and say "hhmmm.."

turn it and inspect the other side and say "fnck..."

commence to grind (sorry no pic) with a handy-and-oh-so-dandy Ryobi bench grinder till you see a hairline separation between the crank and cog

then use a pulley puller to gently separate the pieces (sorry no pic)
View attachment 2
center the cog to the cover plate by inserting the axle from the outside,the stator portion of the axle won't fit through the splined inner diameter of the cog, it should rest around it. Spin the hub/cog to check the cog for high/spots

once it's centered, mark the cover where you wanna drill for mounting bolts (not sure if there's enough space for screw heads between plate and windings, you may have to the drill cog and the plate closer to the axle. washers should be glued on each side of the cover plate for aluminum reinforcement

bob's yer uncle 8)

 

[Dee Jay]

shifting under load would wear out the teeth and chain pretty quickly I imagine...

geared BMC..
that's a whole lot of gears!

nice color, too

[youtube]R5ZdbAGKJ90[/youtube]

 

[Chalo]

That's a clever hack. Seems like you could do the same with a one-piece crank chainring that had a hole pattern in it, though. Ones like this have a 5/16" hole (close to 24mm) and retail for about $6 at my shop:

Chalo

 

[Dee Jay]

That's a clever hack.

thanks!

Ones like this have a 5/16" hole (close to 24mm) and retail for about $6 at my shop:

Crystalyte 4011 and 408 axles are 18.9mm so you'll need a spacer ring between the axle and the cog for better marking accuracy.

Then marking and drilling the mounting holes will be tricky, you'll need a straight shot down with a marker through the sprocket holes to the cover plate

..and you can't use a handheld drill, you have to use a good drill press and drill from the outside in cos I believe some covers have support ribs inside.

oh, you can use a drill press to mark the plate with a spike or a headless nail

This was just a little exercise/experiment, I wanna use a junked 3 gear pressed fit chainring to see which gear is more efficient for the Crystalye 408

 

[Chalo]

Ones like this have a 5/16" hole (close to 24mm) and retail for about $6 at my shop:

Crystalyte 4011 and 408 axles are 18.9mm so you'll need a spacer ring between the axle and the cog for better marking accuracy.

Lucky for us there are these things, made for centering a 15/16" bore sprocket on a 19mm spindle:

Chalo