(ORBO) BACK40 by LTJ, design by OJ. (ROLLING! But withdrawing from the build-off.)

[squirreldh]

I had to google the Firestone Twin Flex. Cool looking bike, early full suspension!!

Was going to suggest paragon machine works. They make some nice machined sliding dropouts for custom builders, but dont think they make them for 14mm axles!

http://www.paragonmachineworks.com/cgi-bin2/commerce.cgi?search=action&category=0006

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[LukeTheJoker]

I had to google the Firestone Twin Flex. Cool looking bike, early full suspension!!

Was going to suggest paragon machine works. They make some nice machined sliding dropouts for custom builders, but dont think they make them for 14mm axles!

http://www.paragonmachineworks.com/cgi-bin2/commerce.cgi?search=action&category=0006

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They do make some nice stuff!

Luke.

 

[gigmata]

As long as you are making the dropouts why not make one that will allow you to change your mind later? Make a sort of multi-dropout like we see on the Sharkfire forks.


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[LukeTheJoker]

As long as you are making the dropouts why not make one that will allow you to change your mind later? Make a sort of multi-dropout like we see on the Sharkfire forks.


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You mean with three or more slots?

Luke.

 

[gigmata]

You mean with three or more slots?

Luke.

How many you think are best. You can change the characteristics of the bike that way at will. Just a thought.


- by Gigmata

 

[LukeTheJoker]

How many you think are best. You can chain the characteristic of the bike that way at will. Just a thought.


- by Gigmata

I like it! Not sure how much room I have in the rear because of the tiny freewheel, but I can always fit different drops to the same mounts. Might do something along those lines at the front too, can raise or lower the front wheel then, that would make a big difference to geometry for going up or down hills.

Luke.

 

[kingfish254]

Digging your framework as usual

 

[LukeTheJoker]

Digging your framework as usual

Thanks King!

Luke.

 

[ECarolinaCruzn]

These dropouts have worked pretty well on my bike. cool thing is you can run gears, or put a separate dropout in for single speed. I think Canfield actually sells these, but probably a little spendy.

 

[OddJob]

Hey Luke, when are you going to finish the BACK40?

 

[LukeTheJoker]

Hey Luke, when are you going to finish the BACK40?

I guess I asked for that one!

These dropouts have worked pretty well on my bike. cool thing is you can run gears, or put a separate dropout in for single speed. I think Canfield actually sells these, but probably a little spendy.

Very nice!

I think I have finally come up with a sliding design I am happy with, so I can start building on it soon!

Luke.

 

[metalchewy]

Those look like they will work out well.

Building... riding...

 

[SILVERKINGPC]

Cool frame LTJ. It sports characteristic lines from all sorts of bicycles! Carbon TT road, Spaceliner, Twin Bar, Straight Bar, Looptail, Bmx, Mountain....& more! I am interested in how you pull off the disc brake caliper mount tabs in the rear. With adjustable dropouts that move forward/back as well as vertically, I wonder what your plan is. Will the vertical axle position end up being fixed, or adjustable? I ask this because as you know, the final bolted position of the axle is crucial for proper caliper/disc alignment. Watching!

 

[OneHorsePower]

Cool frame LTJ. It sports characteristic lines from all sorts of bicycles! Carbon TT road, Spaceliner, Twin Bar, Straight Bar, Looptail, Bmx, Mountain....& more! I am interested in how you pull off the disc brake caliper mount tabs in the rear. With adjustable dropouts that move forward/back as well as vertically, I wonder what your plan is. Will the vertical axle position end up being fixed, or adjustable? I ask this because as you know, the final bolted position of the axle is crucial for proper caliper/disc alignment. Watching!

Mounted on the adjustable dropouts is my guess

 

[SILVERKINGPC]

That may be, but with the large discs, I can't visualize where they would fit on the adj.drops. Only Luke knows the answer to this, and we may have to wait a bit to see what he comes up with! Anything is possible when Ratting, especially if LTJ is involved.

 

[LukeTheJoker]

Those look like they will work out well.

Building... riding...

Thanks MC! I hope they do!

Cool frame LTJ. It sports characteristic lines from all sorts of bicycles! Carbon TT road, Spaceliner, Twin Bar, Straight Bar, Looptail, Bmx, Mountain....& more! Watching!

Thanks SK! I am not ashamed to say that I 'borrowed' ideas from all over the place on this one and OddJob kicked in the curved seat tube and refined the design a fair bit too!

I am interested in how you pull off the disc brake caliper mount tabs in the rear. With adjustable dropouts that move forward/back as well as vertically, I wonder what your plan is. Will the vertical axle position end up being fixed, or adjustable? I ask this because as you know, the final bolted position of the axle is crucial for proper caliper/disc alignment.

Mounted on the adjustable dropouts is my guess

That may be, but with the large discs, I can't visualize where they would fit on the adj.drops. Only Luke knows the answer to this, and we may have to wait a bit to see what he comes up with!

1HP has it right, they will be mounted of the dropouts. The axle will only move forwards and backwards, not up and down, I did look at making them move up and down as well so that the geometry could be changed for different riding styles, but it just became to fiddly and too many moving parts. It could be done with a more standard frame, but with a looptail and the seat tube being a tight arc over the tire it was just too much going on. I have the dropouts made now, and the start of the calliper mount, and will post them in the next post so you can see them.

Anything is possible when Ratting, especially if LTJ is involved.

Thanks SK! Glad you are enjoying following along!

Luke.

 

[LukeTheJoker]

As mentioned in the previous post, the drop outs and sliders are started!

Cut out the drawings I made and traced around them on to some 5mm (1/5th") plate, then tacked the two sides together and went to town with a cutting disc and grinding wheel:

Got them close to where I wanted them and drilled the holes. The slots are drilled 8.5mm to clear 8mm bolts and the holes were drilled 6.5mm and then tapped to 8mm, you can also see here the extension to hold the brake calliper on the off-side dropout:

Worked a bit more and started on the slots:

There will be lots of filing yet to finish the slots off, but that can wait till another day, I also will be slotting the axle holes, but only after the sliders are tacked to the frame, this way the axle can help to locate everything properly for tacking. I may remove some steel from the brake mount extension too while tiding the sliders:

I had to test fit!:

Not a bad days work and now I have the next few work days figured out there should be some good progress in the coming days!

Luke.

 

[SILVERKINGPC]

So there it is! The tall caliper mounting posts appear! Disc brakes are just superior stoppers in every way. Nice job Luke...

 

[OneHorsePower]

Amazing what you can do with a grinder and a drill . looking great !

 

[ind-chuckz]

Looking good!!