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Discussion Starter · #1 ·
Dual crown, rigid, carbon MTB fork.

Is "Lefty" a reg. trademark?






Just spent a couple days getting the molds for these
(left and right sides) done.

536 g's. included the weight of a 1/2 x 2 1/8 x 5" hunk of 7001 series for the top clamp and rotor bracket. (should be less after milling).

Will make one (with both legs for the Fattie) Each leg can be about 30% lighter so wonder what it will weight?

Too bad I have to break this one :p

JM
 

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Man, I know it's kinda structurally silly but when it came to changing flats, lefty forks are so cool.

Not only do you avoid removing the wheel, but the bike serves as an impromptu stand for the wheel.

I'd ride a single sided entire frameset without complaining, save for the gawking it would receive.
 

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Discussion Starter · #4 ·
Thanks,

Also going to use these legs for a "linkage/girder" Girvin, Noleen, Fournales/Look, type.
Along with a single pivot rear on the same frame.
The mold is "modular" so I can use the front triangle with any (axle width) or the full boing rear.

Was supposed to get to the frame this week but ran out of cloth after building the molds and some customer parts.

Takes 10 days for a 100 yrd. roll to get here from my supplier in MI.

JM
 

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Very interesting! I've been thinking about a single-sided fork also. Can you share more details of the fork/hub interface? How are you securing the axle to the fork leg? Thanks!
 

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Discussion Starter · #7 ·
Have the "convertible" hubs that come with 15, 20mm and QR adapters.

Will turn a custom axle with the 20mm at the fork end tapering to (whatever I need to adapt the QR cup side. (just to clean that side up, making it almost flush-mounted like some trike hubs. 10 mm Ti fixing bolt. (6 mm at the other end)

Just pulled a 15mm axle off one of my trike builds to mock-up.

Dropped 4- 45 lb plates on it from 4 feet today. Bent my fork jig.
The single-sided thing is hard to jig up. (for testing.

The Euro test drops 90 kilos from 1 meter. Then they "cycle" test for tens of thousands of cycles under load. That was a test I could not (easily) replicate when testing my race bike forks.
So I dropped the 180 lbs from 5 feet 5 times. Then put it on a friends press with a strain gauge and it took 27-2900 lbs of force to break (tested 3 forks total)

Am going to just go ahead and run this fork as is and pay attention.
Can add some rivets and/or bolts to back up the adhesive on the lower tree plate.

There are a couple methods I could use to secure the trees that would be fail-safe.
If a customer HAD to have one of these on a build I might go that route?

Was messing around with the girder linkage geometry between coats of PVA today.

A single-sided linkage fork might ROCK?!

Laying up the main frame tomorrow!!!
Will spend the rest of this week on this (vanity;-) build.

JM
 

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Discussion Starter · #11 ·
I honestly had not seen it done before.

But I KNOW, there is almost nothing you can think of that has not been tried/done before.

Man, that's so "2011".

Thanks!
 

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Discussion Starter · #16 ·





Bike has been ridden hard all over the usual Front Range trails and up in the mountains.

Could get the 2.4's to rub going over some woops at a BMX type section.
Ended up running Kenda Karma 1'9's. Same tries I run on my other 29'r for years.

Been on rocky stuff. Nothing extreme.
Prefer buff single-track high speed riding.

Thanks

JM
 

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Discussion Starter · #17 ·
The fork does deflect as you would expect.
Nothing drastic.
Ended up beefing them up below triple-tree.

Was just looking around the shop at un-finished projects.
There are a set of the same legs, (left and right) sitting there along with the "three-spoke carbon, air-tank/expedition wheels"

Need to finish them and either mount up to existing Fat-bike frame or go ahead and build a new frame same as above with wide rear and both seat/chain stays?

The front triangle is modular so I can run any rear triangle I want.

JM
 

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Enough about the fork, tell us more about the bad-ass asymmetrical rear triangle! Certainly makes chain replacement easier... How does it hold up torsionally?
 

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I can only imagine there is some flex. Awesome to hear it's been holding up for some good riding. Seems like you know your way around a layup.

Are you doing the layup on each side of the frame mold and then bonding them together?
 

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Discussion Starter · #20 ·
Yes,
should have specified; the rear tire moves up and to the left as expected/predicted.

Enough that when getting a (little) air over the whoops I could get the 2.4's to graze the seat stay. Actually like the 1.9's better for the weight savings.
Brakes and crank are quite portly. (still have 2 full sets of XT brakes leftover)

I DO build everything in "two halves" with a spline or "joggle" bonding them together.

The way I have been doing the stays. They are complete when molded so no secondary bond there.

Re-inforced the chain-stay when I beefed the fork.
Could have also beefed up the seat stay but this frame was only slightly over 3 lbs.

They are also building some aero TT bikes this way. I have built tubes (tapered and radius' of course) and just bonded the or made lugs also.

Frames can be stronger with less gluing surface area when bonded on centerline.

Also looks cool as hell have the herringbone pattern at the seam :)

Need to make some fat fenders. With the "two-half" method I can change the width with one set of molds. A little heavier for fenders but stiffer w/the spine at center.

JM
 
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