[troy]

Update at post #41 (top of the 2nd page)

So yeah, season is over, DH01 came out really awesome, time for an Enderpo bike!

Spec
26" wheels
6.3" travel (160 mm), high single pivot with 0.6" (15 mm) reward travel
Idler (not shown)
66* HA
73* STA
16.53" CS (420 mm)
13" BBH (330 mm)
46.65" WB in Large size (1185 mm)
18.11" Reach (460 mm)
44mm HT
142 x 12 mm axle, 73mm standard BB
Low Direct mount front der. (Sram S3 type/Shimano low DM)
Post mount 74mm DM rear caliper 180mm (not shown)
ISCG 05
7,5 lb~ without shock
True Temper Supertherm/OX Platinum tubing
7075 T651 liinkage
BB main pivot 24 mm axle
8,5x2,5" shock (216x63mm)
accepts every seatpost size with a reducer.

Very supple begining of the stroke, progressive feel through the travel. Idler for nice anti-squat and lower pedal feedback.

Wanna built couple of frames for testing (Enduro and some DH but not DH01), and hopefully start a small company in the end of this year. Any thoughts, sugestions or ideas?

 

[tacubaya]

Looks flexy

 

[troy]

But... it will come in rootbeer. Does that fix that issue?

Seriously tho: TT supertherm is BMX super strong STEEL tubing.
44mm DT/38 mm TT, those CS plates are 5mm thick. Haven't done rear triangle FEA yet, but it should be plenty stiff. It's just a "proto", so some bits are missing.

 

[jstuhlman]

if it's at all like your other bike...#baller

 

[MmmBones]

the rear end is going to behave like the tacoma narrows bridge in 1940, needs moar stayz

 

[troy]

Looks flexy

the rear end is going to behave like the tacoma narrows bridge in 1940, needs moar stayz

Where will it flex exactly in Your opinion? On those plates or the tubing? In what direction and under what load? Can You draw it in Paint for example?

 

[ChrisRobin]

Need room for coil over shock. Looks cool

 

[troy]

Need room for coil over shock. Looks cool

There is plenty CCDB Air with LV can fits without a problem, so any coil shock will fit as well.

 

[SDet]

I'd think the plates would be fine. The box should be stiff as long as your pivot axle is good. What size tubes is the rear triangle made of?

 

[troy]

I'd think the plates would be fine. The box should be stiff as long as your pivot axle is good. What size tubes is the rear triangle made of?

Steel is around 3x more stiff than even 7xxx grade aluminium. Those plates in CS are 5mm thick so an aluminium equivalent would be made from 15mm thick plate. Haven't done FEA work to the rear triangle yet, but it if any flex/twisting will occur it will be on the tubing.

Those are 22mm x 1,25mm tubes (really stiff stuff), if FEA and some future testing will show some problems i will try to do it with 2x 19x0.9 tubing (on drive side). It will be quite hard because of an idler placement/chainline issues.

True Temper Supertherm tubing comes in limited sizes, that is why this frame looks like it looks. For that reason I'm thinking of using some mix of Supertherm tubes and 4130 normalized tubing. I would need to heat treat the whole frame after welding then, so for prototypes I will stick to TT Supertherm tubing only. For production models I will probably go in that direction! Some rectangular 38x19mm profiles would be great but they are very hard to get with really thin walls and as it is an enduro frame weight is a big factor.

 

[Jm_]

This too has been done before.

 

[troy]

This too has been done before.

I'm sorry, I do not understand. Can You elaborate on that?

 

[Jm_]

Moto-link with single-tube swingarm, although I do admit I haven't seen even a steel one with a rear swingarm that small before. Also, those flat plates that weld to the ends of the swingarm tubes and connect to the pivot are going to be huge sources of flex, nowhere near the stiffness of a tube. Also, the moto-link pivots on these types of designs usually end up seeing very high loads. Definitely do-able, but many of these style bikes have had crap bearing designs in that area over the years.

 

[troy]

Moto-link with single-tube swingarm, although I do admit I haven't seen even a steel one with a rear swingarm that small before. Also, those flat plates that weld to the ends of the swingarm tubes and connect to the pivot are going to be huge sources of flex, nowhere near the stiffness of a tube. Also, the moto-link pivots on these types of designs usually end up seeing very high loads. Definitely do-able, but many of these style bikes have had crap bearing designs in that area over the years.

@Jm_ thank You for Your input! As I said, haven't done FEA for rear triangle yet. It is just a 3d model so don't worry. Those flat plates shouldn't be an issue at all (please read my earlier post).

As You said, many of those designs failed because of poor engineering. Unfortunately nothing uncommon in the bike industry

 

[SDet]

I didn't see the plates on the swing arm. I'd be worried about them. Even though steel is 3 times stiffer, your area moment of inertia, stiffness of the shape, Doesn't change linearly with size. Treating your flat pieces as rectangles, the stiffness depends on the thickness cubed. In short, an 8mm thick I-beam of 7xxx aluminum would be stiffer. I strongly recommend a machined piece. The rear tubes look fine though, around 10 times stiffer than the plates in pure bending.

 

[TrumbullHucker]

hook that frame up to some stress analysis solidworks ( if you haven't already )

pretty sure @troy has it in the bag with his last beauty

 

[jonKranked]

turner called, they want the linkage to the old DHR back

 

[StabprimoMonkee]

As You said, many of those designs failed because of poor engineering. Unfortunately nothing uncommon in the bike industry

The designers of which always claimed that other engineers have no idea what they are doing.

 

[troy]

Moment of interia for flat plate depends on qubed height of the profile not thickness, depending on what direction we are talking about As I said, CS was not calculated at all (except some quick buckling loads calculations for tubes etc) an will be changed. It is just a model to check for interferences with cranks, fd and idler. Stay tuned

 

[SDet]

I was looking more at lateral flex.

 

[troy]

I will try to make it 27,5" compatible. What do You guys think about posted geo but with 27,5" wheels? What would You change?

 

[Sandwich]

Where does the idler go? At the little hole that's just chilling there, or at the pivot? Personally I'd rather see one just below the pivot for a little added AS without jacking up the pedal feedback.

I say triangulate the swingarm. The brooklyns had more significant swingarms and were pretty much noodles when it came to handling. I would think you could add a second tube to each side (so it's no longer asymetric) and brace them a bit, and you've have a nice robust piece.

Just my two pesos. I'd be in for one if you can clear a twennyniner for me. 110/120mm of travel, wagon wheels...yipee.

 

[OBB]

I'd knock the STA forward 1 to 1.5 degrees, while reducing the effective TT length ( I see that isn't published). 460mm reach long for a size LG, even with a 40mm stem but you might have your reasons for it. Shortening the ETT will give a better seat climbing position, closer to the front wheel.

 

[shirk007]

Looks cool. Interested in seeing how the FEA comes out on the swingarm.

 

[troy]

Where does the idler go? At the little hole that's just chilling there, or at the pivot? Personally I'd rather see one just below the pivot for a little added AS without jacking up the pedal feedback.

I say triangulate the swingarm. The brooklyns had more significant swingarms and were pretty much noodles when it came to handling. I would think you could add a second tube to each side (so it's no longer asymetric) and brace them a bit, and you've have a nice robust piece.

Just my two pesos. I'd be in for one if you can clear a twennyniner for me. 110/120mm of travel, wagon wheels...yipee.

Yes idler goes through this hole, so it is below the main pivot to get nice AS curve and reduce pedal feedback. I will triangulate swingarm for sure using square/rectangular profiles.

I'd knock the STA forward 1 to 1.5 degrees, while reducing the effective TT length ( I see that isn't published). 460mm reach long for a size LG, even with a 40mm stem but you might have your reasons for it. Shortening the ETT will give a better seat climbing position, closer to the front wheel.

to 74/74.5 de. You mean? This is a good idea. Thank You guys for the input!

 

[IH8Rice]

Seriously tho: TT supertherm is BMX super strong STEEL tubing.

ive heard about how great it is but the three DH bikes ive seen made with it have all broken

 

[troy]

ive heard about how great it is but the three DH bikes ive seen made with it have all broken

You can say that about almost every material. Everything depends on design, tubing selection and post welding heat treatment. Supertherm tubes are not very popular because its thicker BMX tubing that comes in short lenghts (too heavy and too short for typical hardtail). If something breaks it's usually fault of either design/poor welding or an accident. From what I see on the market none of either 4130 or Reynoplds/Columbus/whatever frames are PWHTed... Can You post some pics of those failures? I guess those supertherm tubes were welded (I hope they were TIG welded) to some cro-moly and it simply failed in cromoly HAZ or it buckled due to wrong tubing selection and geometry.

 

[IH8Rice]

Can You post some pics of those failures? I guess those supertherm tubes were welded (I hope they were TIG welded) to some cro-moly and it simply failed in cromoly HAZ or it buckled due to wrong tubing selection and geometry.

all of the failures were similar to what you described..ill shoot ya a PM

 

[no skid marks]

I say triangulate the swingarm. The brooklyns had more significant swingarms and were pretty much noodles when it came to handling. I would think you could add a second tube to each side (so it's no longer asymetric) and brace them a bit, and you've have a nice robust piece.

This would make it a stiffer swing arm, but you're still only using single pivot with the shock/link location not aiding much in stiffness with it's close proximity. Using your DH01 design for triangulation would provide a stiffer rear, but you're not wanting to reuse the DH01 design due to hassle of manufacture correct? If doing as Sandwich suggested and adding more tubes to the swing arm, would it be much more work to just make a mini DH01 instead? Love that design.

 

[kidwoo]

Moar chainstays

Final answer.

 

[jstuhlman]

oh, i thought moar toobs? maybe same thing.

 

[troy]

This would make it a stiffer swing arm, but you're still only using single pivot with the shock/link location not aiding much in stiffness with it's close proximity. Using your DH01 design for triangulation would provide a stiffer rear, but you're not wanting to reuse the DH01 design due to hassle of manufacture correct? If doing as Sandwich suggested and adding more tubes to the swing arm, would it be much more work to just make a mini DH01 instead? Love that design.

I will definetly make DH02 and EN02 using DH01 design (probably with different tubing). For now I want to make something simpler, easier for production and cheaper to make with lower MSRP. Don't wanna risk doing more complicated design and dealing with some f*ups during production (alignment issues were strong with this one). For now I'm thinking of a swingarm like on BB7/appalache frames (but much shorter) so I will keep the weight on reasonable level and increase stiffness.

oh, i thought moar toobs? maybe same thing.

Son I'm disappointed. Correct answer is: RUX, always RUX. Remove swingarm > put RUX instead. Moar RUX!

 

[jstuhlman]

hmmm... i'm a fox/ccdb guy myself. you must have me confused with da peach. but i'll oblige. still looks flexy.

 

[troy]

I have to do some more FEA, maybe I will go with mini DH01 design and normalized 4130 tubing + stress relieving after welding... I'm wondering how much I can reduce weight of that thing. DH01 front triangle is ~ 1.1 lb heavier than EN01, so it is doable I guess. Kinda hard to ignore all this positive feedback about DH01 (which is far superior design to current EN01) Got to think about it...

 

[troy]

looks flexy.

Because You have used the wrong RUX bro... (mad ps skillzz btw )

This is THE RUX

 

[jstuhlman]

new rux is moar rux-ier? who knew?

 

[Trasselkalle]

As 'moar Rux' appears to be the ideal, any new model should by default be 'moar Rux', shouldn't it? I've always wondered though, as 'moar shimz' also appears to be a universal solution to all situations in life, if moar shimz is better than moar Rux, or vice versa, or even if moar shimz in a Rux makes it even moar ruxy?

But then again, I may have had too much coffee today and lost my final marble.

 

[jonKranked]

This would make it a stiffer swing arm, but you're still only using single pivot with the shock/link location not aiding much in stiffness with it's close proximity. Using your DH01 design for triangulation would provide a stiffer rear, but you're not wanting to reuse the DH01 design due to hassle of manufacture correct? If doing as Sandwich suggested and adding more tubes to the swing arm, would it be much more work to just make a mini DH01 instead? Love that design.

if the pivots are the same as the DH01, they are massive 24mm spindles w/ external bb bearings. should be plenty stiff.

 

[Sandwich]

For now I'm thinking of a swingarm like on BB7/appalache frames (but much shorter) so I will keep the weight on reasonable level and increase stiffness.

that's what I was thinking. Just a nice clean triangle that mounted to the same plate setup/ pivot.

The only problem I can think of with that linkage setup is the limits it places on chainstays length, and the possibility of being a mud catcher.

 

[no skid marks]

I have to do some more FEA, maybe I will go with mini DH01 design and normalized 4130 tubing + stress relieving after welding... I'm wondering how much I can reduce weight of that thing. DH01 front triangle is ~ 1.1 lb heavier than EN01, so it is doable I guess. Kinda hard to ignore all this positive feedback about DH01 (which is far superior design to current EN01) Got to think about it...

Sweet. Surely you can sort out the alignment issues with good jig, might be more work initially, but you'll end up with better frames with better geo and a possibility of a 29er, not that a 29er will benefit as much from a higher pivot as smaller wheels, thanks to 29ers better roll over. Still be cool for big wheelers. and will allow shorter stays for a 29er.

if the pivots are the same as the DH01, they are massive 24mm spindles w/ external bb bearings. should be plenty stiff.

large sealed bearings, plates, tubes twisting, might all be small amounts of flex/tolerances, but would all add up I'd imagine. Wonder what his computer analysis has said.