[A Grove]

Well... as most of you know, I've been working on designing a new frame around deuce-quads. I wanted to keep a very similar look while making drastic geo changes as well as dedicating it to 24's. I've also been dreaming up a sus-corrected rigid fork for almost a year now... Currently, the market is filled with "rigid dj/park forks"... But the problem is that their a2c's are VERY short compared to what most people like running on their MTBMX's.

BLKMRKT contraband: 435mm
NS fundamental: 440mm
NS rns: 430mm
DMR Trailblade: 440mm

...Thats a full 40-60mm short of any stock "DJ" fork at 100mm travel. This is great, if that is what you are looking for. But I just want to loose the sus and some weight for a rigid and keep the same geo. After laying things out in cad and coming up with a few designs, I settled on one that was based off the old Hardcore forks my dad used to produce.

Specs on the fork... It's gonna get built around a 20mm, hollow Ti axle that has the abilities to run pegs via 14mm male bolts (thread into axle). Hollow box crown, straight, bladed fork legs for a unique look, and a very burly chromo steer. The fork is going to be built to withstand the forces the bike is going to see with straight-gauge fork legs and heavy walled crown. The forks are going to be built at two a2c's for both crowds (short vs. tall), but am also able to make a custom fork at any a2c.

As for the frame.. Looks very similar to my current and past ride. Going to be using the same overall frame design (flame away...) with a few nice features....

NEW
-Mid BB
-Internal H.S.
-110x14mm rear end (3/8's if desired..)
-990's or Vee's
-Redesigned geo for 24's


GEOMETRY
TT (effective): 22.25" or 23.5"
ST (center-center): 11.25"
HT/A: 70*-71* (around a 455mm a2c)
ST/A: 72*
CS: 13.75"->14.5"
BB: 12.25"

Been designing it out in SolidWorks/cad and thus far.. I am lovin' what the final product is going to be. Below are some screenshots.. and I am expecting the flame-age, so bring it on. (PS. the fork dropout area will look a lot more refined in real life, I just didn't bother to go into massive detail in the model... and yes, it is modeled with a euro BB/external HS cups, but that wont be so in real-life.)

I am building up a small run of 4 frames, and 10-15 forks. I am wanting to get these out to the public/people who ride hard for cheap. I want to get some good feedback and have them put through their paces. Not going to post up prices, but if anyone is interested in anything, let me know...


Feedback is always appreciated, but I would ALSO appreciate it if you left the profanity/rudeness/harshness to pinkbike. THANKS!

-Aaron

 

[Bikael Molton]

cool project.

for apples-to-apples comparisons to other frames, could you post actual TT length?

another point is that i don't think most riders are running DJ forks at 100mm length, regardless of whether manu's are selling 'em at that length.

-rob

 

[A Grove]

Agreed.. I was using that as an example. Most like to run them at 80mm or a tad lower. But, there is nobody making one for that spec.

I'll grab the actual once I get home from school.

Also have been working on layout for a chromo stem and bars...

 

[davemo7]

That looks good, i like the crossed headtube/downtube design. the fork looks sweet as well, im excited to see what it all looks like IRL

 

[ServeEm]

not really into the crossed bars but I can see it's benefits. Do you think you'd get some twisting flex on those forks being that tall?

 

[dexter]

id be interested in testing out a rigid for a bit.

 

[A Grove]

Aye... I am into "unique" designs. Hence why I've stuck with what I had started with. But it seems most do not like the design/can't adapt to change. No biggy, I'm mainly building it for myself and a friend than the general public.

As for the fork.. It should be very stiff, BUT I have been talking with my pops about adding a "arch" above the height of a normal 26" wheel. It will help to stiffen the fork A LOT as well as add some "sex appeal" IMO.

Dexter.. you've got a PM.

 

[jonKranked]

Just a thought... why the decision to use straight bladed legs as opposed to tapered? Tapered (if done properly) would be a bit lighter, but you'd have to do a different style dropout for the 20mm axle. Just aesthetic reasons?

 

[A Grove]

Good question..
Tapered legs, while being lighter, flex a lot. I am building the fork to be stiff, strong, and have the abilities to take abuse. Another reason is because finding tapered fork blades that would be long enough for a sus corrected for and also have the strength required is practically impossible. Tapered legs aren't something that any average machine-shop can produce.. as opposed to the legs we will be using. Which I will be flattening myself.

 

[jonKranked]

Gotcha. I was thinking something along the lines of the Fit shiv fork (for 20"). The legs are tapered, but the wall thickness stays the same (or does it slightly increase?) as the OD of the fork leg decreases, so its actually stronger than a straight tube (or at least this is what I've been told). Also read that this holds true for tubes in a frame design book, not Paterek's, the other one (can't remember the name offhand). Its a process you take a straight (i wanna say single butted) tube and heat treat it and roll it down so it is eventually tapered (something along those lines).

 

[ServeEm]

Aye... I am into "unique" designs. Hence why I've stuck with what I had started with. But it seems most do not like the design/can't adapt to change. No biggy, I'm mainly building it for myself and a friend than the general public.

As for the fork.. It should be very stiff, BUT I have been talking with my pops about adding a "arch" above the height of a normal 26" wheel. It will help to stiffen the fork A LOT as well as add some "sex appeal" IMO.

Dexter.. you've got a PM.

I'm all for change just don't care for the look of a crossed design. Plus I'm sure you're aware that it's been done quite a bit.

The original comment wasn't to be rude or disrespectful, just my opinion which is what I thought you were looking from the public.

 

[WestCoastHucker]

i still don't like the looks of the crossed tubes and i think the fork is kind of silly looking running so much lead, but wish i had the resourses to go at it myself and produce my own ideas. props...

 

[WestCoastHucker]

this is merely e-speculation, but it seems to me that a fork built that was has 2 inherent design flaws...

1. the fork is more difficult to x-up/barspin because of the added mass outside of the rotational axis(the whole fork leg opposed to the dropouts only)
2. the increased fork leg angle makes the frontside of a landing pushing in opposite angle more condusive to bending your fork on cases and 50/50's...

 

[A Grove]

serveem- that part of the comment was not directed towards you. I should've worded it differently. I have the opinion that younger kids into this style of riding (and BMX especially) tend to get very "uneasy" when the idea of change falls into their riding. Whether it be frame design/looks, how someone runs their bike, etc. They have this "perfect image" on how every ride should look, and when one strays away from the image, it tends to instantly be bad.

Thanks for the honesty, If I was aiming to please the public as a whole with this design, I'd be screwed, and I know that

jonKranked- looked into what forks you're speaking of... never heard of them before. But after looking at them, the tapers FIT is running are very minute compared to what is available in lengths long enough to build a 26'er fork. Not to mention, they're all designed for XC and road... not bashing and thrashing.

 

[A Grove]

this is merely e-speculation, but it seems to me that a fork built that was has 2 inherent design flaws...

1. the fork is more difficult to x-up/barspin because of the added mass outside of the rotational axis(the whole fork leg opposed to the dropouts only)
2. the increased fork leg angle makes the frontside of a landing pushing in opposite angle more condusive to bending your fork on cases and 50/50's...

Aye... missed this before. But that is what the testing stage of production is fork Looks can be deceiving when it comes to strength/physics.

 

[Bulldog]

No biggy, I'm mainly building it for myself and a friend than the general public.

If only building for yourself why worry about stock manufacturer fork a2c? If it's just for you, you built a fork longer/heavier/flexier than needed, then built a frame geo around that tall fork. Reading your first post I figured you had to be designing the fork for sale to the public, thus the a2c considerations, but now I'm just confused. Or is what you're building for yourself just the frame, and the fork will be produced for sale?

 

[sittingduck]

Are you going to run a suspension fork on it at some point? If not, the short steer tube and long fork is counterproductive. You weaken both by going that route.
Why not make your head tube a little taller, use taller bars, and build it around a normal 24" fork?
The long forks only exist because the mtb frames are all built around suspension. I want to see some frames like the Melms, and what Cru is working towards.

 

[duck]

It looks great so far, and it sounds like you've put a ton of time into this project.

Keep us posted on the progress!

 

[A Grove]

Sorry for the confusion.. I am making the frames for myself and a friend. I have extra tubing around, hence why I am making two extras. I plan to swap between sus and rigid.. and if I end up liking the rigid specifically, I'll build up a cruiser. But I don't think I'm ready to give up suspension yet.

I am wanting to refine the forks to the point of producing them for the general public, yes.

 

[jonKranked]

jonKranked- looked into what forks you're speaking of... never heard of them before. But after looking at them, the tapers FIT is running are very minute compared to what is available in lengths long enough to build a 26'er fork. Not to mention, they're all designed for XC and road... not bashing and thrashing.

I'm sure with enough hunting you could find something reasonable in terms of a suitable butted tube with the proper dims. Or maybe its just not worth the effort

Here's another thought... maybe an internal reinforcement?

 

[A Grove]

I'm sure with enough hunting you could find something reasonable in terms of a suitable butted tube with the proper dims. Or maybe its just not worth the effort

Here's another thought... maybe an internal reinforcement?

I like your thinking... But to be honest, I don't think I would like the look of tapered legs on these forks.. I want to be able to look at the forks and have faith in them. Plus the final cost to the consumer would be quite a bit higher having to special-order from a frame supplier and also the added work/weight in reinforcement.. I'm not sure it would be worth it.

 

[Leethal]

A G,

I would add the arch on the fork, but would not worry about the other speculation.

 

[greenblinker104]

real men use pro/e

 

[jonKranked]

real men use pro/e

but with the price difference you can buy a LOT of tubing.

 

[jonKranked]

I like your thinking... But to be honest, I don't think I would like the look of tapered legs on these forks.. I want to be able to look at the forks and have faith in them. Plus the final cost to the consumer would be quite a bit higher having to special-order from a frame supplier and also the added work/weight in reinforcement.. I'm not sure it would be worth it.

NO NO NO YOU HAVE IT BACKWARDS!! ITS FUNCTION OVER FORM!!! :biggrin:


just kidding. I'm sure it'll be sweet. I might even know a few people that would want one.

 

[A Grove]

real men use pro/e

but with the price difference you can buy a LOT of tubing.

I tend not to complain whenever I get the program(s) for free

But I would dis-agree on the pro/e comment... but this isn't the place for that argument.

Thanks Leethal. I plan to add on of some sort as it would also serve good purpose for footjams, etc.

 

[grom-dom]

go for an integrated headset and a mid bb shell. wayyyyyyyy better

 

[A Grove]

You're reading comprehension skills amaze me But for my frame, it'll have a euro BB.