CNC Swingarm 'Gull Arm' Whats your opinion?

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The Atomic Reign 150M's look OK ...... That alloy frame you posted a pic of would be good if they left a 10 mm thick web in the centre of the back bone and made the top and bottom parts thicker (like an "I" beam) instead of chopping all those diamond shaped holes thru them ..... You only need to take a look at the shape of railway line and the massive weight and flexing it can handle to realise that "I" beams are super strong .... (girder , conrods , spanners etc)

The Motovert Pro alloy frames are pretty impressive when it comes to strength and design ..... has anyone seen one of those break or crack thru the spine yet ??????? It's fricken hard to find pics of a bare frame though .....
 
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ducar.r.spec said:
my frame looks similiar in pics
look at some of the holes in the frame u can see the machining
Click to expand...

Your frame is far better quality than that Ducar .... :p Yours is very similar to a Thumpstar TUV frame .... the small holes weren't there for looks .... they were there to help get the shape of the bend right .... the original Thumpstar frames were fairly heavy , dense metal so the bigger round holes were machined in them after the bending process to lighten them a bit .... I'm pretty sure Vickers wanted $800 just for a bare back bone part .... with no rear sub frame .... they wanted $1200 for a twin spar frame minus the sub frame .......
 
i am 100% happy with my frame its been a few months now and it hasnt bent/crack or warped
non of the mount holes have been ovaled out
and im running standered ball bearing in the stem
heres a recent pic
reecespics052.jpg
 
Cactus Jack said:
Your frame is far better quality than that Ducar .... :p Yours is very similar to a Thumpstar TUV frame .... the small holes weren't there for looks .... they were there to help get the shape of the bend right .... the original Thumpstar frames were fairly heavy , dense metal so the bigger round holes were machined in them after the bending process to lighten them a bit .... I'm pretty sure Vickers wanted $800 just for a bare back bone part .... with no rear sub frame .... they wanted $1200 for a twin spar frame minus the sub frame .......
Click to expand...

lol yeah had 1 here that i pulled some parts off
was beautiful great quality
if i could get 1 now i would
 
Yes the frame at the front is the strongest if you get rid of the mill marks which are stress risers and not machine so much off the bottom rail . Leave it like the top one and eliminate the triangular holes plus put the fricken bolts back in ..... bolting is actually stronger than welding and rivetting is even stronger still .... Welds fatigue and crack plus weaken the parent metal , that's why bridges such as the Sydney Harbour bridge are fully rivetted and have zero welding ..... They've machined the bottom frame rail so the spine is like an upside down rail line ... frames start breaking from the bottom rail which tries to stretch .... so the lower rail or tube should be stronger or at least as strong as the top which gets compression force on it ..... What are the other two frames ? Pitster X3R and Motovert Expert ? We know how the extreme rear frame fares on a decent landing .... and the X3R frame I wouldn't trust if the 4 bars are hollow ......

Ducar , I was talking about this type of frame that I thought you bought off Snitchy .....

allybike3valveframe.jpg


Here's a genuine Thumpstar frame ....

Thumpstarbilletframe.jpg


And here's I-Thumps' pic of the lattice work alloy frame .... which looks like a genuine prototype carved out of solid billet alloy .... the frame you get sold would most likely be a cast alloy copy of that frame ....

ALLOY_CRADLE_WEB-1.jpg
 
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Cactus Jack said:
That may well be mountain ... I don't know about the frame that I-Thump posted pics of but I have personally inspected genuine Thumpstar T-6 billet frames (the TUV certified solid billet spinal frames) and was quite impressed with them ...... the TUV certification was stamped into the frame ...... they most certainly definitely didn't look like they were made in China .... the spine part was one solid piece that was bent by high powered hydraulic roll forming machinery ..... the human riders bones would snap and crush long before those frame back bones ever bent ......

It doesn't matter where in the world things are made these days .... most of the parts are made by million dollar Computer Numerical Control Machinery .... the workers just handle and assemble the finished machined parts . Hi quality parts can be made anywhere ....
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The first ones were made in taiwan in a very known Bicycle factory which build frames for Specialized, Merida and Giant!! They are really good no doubt!
 
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Have you ever noticed how tiles or glass are cut ???? You score it then snap it ... or you can even heat it then cool it and it will crack cleanly and neatly along the score line .... When you score anything you create a stress riser which means that all the load will be concentrated in the bottom of the "V" where the section of the material is thinnest ........ mill marks act as stress risers just as if they are multiple scores .... for strength in metal preparation the surface would be smoothed and polished ... then shot peened to increase metal density to help prevent cracks from starting .....

There you go .... anything I say can easily be checked out by anyone with a quick google search :

milling marks are stress risers - Google Search

Shot peening - Wikipedia, the free encyclopedia
 
Thanks cactus, I value your opinion on this subject so I got one more frame that I would like to hear your thoughts on.

Do you think this alloy frame would be worth over $250?

ALLOY_CRADLE.jpg
 
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looks weak at the bottom section of the frame where the engine mount and rear swingarm attach to the frame. looks like paper. (I-thumps frame)
 
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Flarry said:
Nah I baught that one from snitchy, got it in my honda.

People seem to sell the genuine thumpy ones for around $300 and Ive heard they're not real billet alloy and just cast on planet mini's a few times, Im not sure if its true.

Apparently the good ones are the ones by fast50s.
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Right ... I can recall you PM'ing me about it but I somehow thought that Ducar bought it ...... great score dude !!!!!! Yes the Fast 50's frames look good ..... don't trust everything you read on Planet Minis .... the moderators are 22 year old kids who think they've got the engineering knowledge of an 80 year old NASA engineer ....... :p They argue about engine balance factors and harmonics not being the cause of broken cranks ...

Here's a few links on engine balance etc . That guy hits the nail on the head when he says that most of the people modifying engines don't have much of a clue on the basics of physics ......:

ATI - The Dangers of Power Pulleys & Understanding the Harmonic Damper

And in this link they state that stock engines are balanced for stock general use ... but the moment you start racing them or modifying them .... the stock balance factor is inadequate ......

Crankshaft Balance Factors

I can assure you that the original TUV certified Thumpstar frames are GENUINE high quality billet alloy ..... the proof is in the fact that nobody can show a broken early Thumpstar billet frame and that blows away any BS people may come up with ...... and the fact that they still sell for $300 tends to back that up ...... bad frames or anything for that matter lose value very quickly . Also .... people who own them must be pretty happy with them because I've never seen one listed on ebay .....
 
gull swing arm

this designed by a man in China GUANGZHOU and it looks strong we made 20 bikes with this frame and swing arm see pixes and fit 10/10 wheels for supermoto use then fit 250lbs FASTACE BR58AR shock on it now i know it's not worthable to purchase this expensive i would rather buy a original CRF bike if pay for 1350USD i still have two frames like this in shop but now it is with dust
 
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Cactus Jack said:
I can assure you that the original TUV certified Thumpstar frames are GENUINE high quality billet alloy ..... the proof is in the fact that nobody can show a broken early Thumpstar billet frame and that blows away any BS people may come up with ...... and the fact that they still sell for $300 tends to back that up ...... bad frames or anything for that matter lose value very quickly . Also .... people who own them must be pretty happy with them because I've never seen one listed on ebay .....
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Yeah you see a few 05 thumpy pro's with honda's in them around today because the gearbox is the only thing that deosnt last in them, so they replace them with a honda engine.

And in reply to your other post, TJ russel managed to snap a motovert pro frame, dont know where/how it snapped though.
 
I_THUMP said:
Thanks cactus, I value your opinion on this subject so I got one more frame that I would like to hear your thoughts on.

Do you think this alloy frame would be worth over $250?
Click to expand...

When you ask about frames you have to state the intended end usage ..... For motard or road riding ...... ANY alloy frame will obviously work OK ......

But for off road riding where the frame gets subjected to varying loads and constant pounding .... then the alloy needs to be SOLID to deal with it and last for a long period of time .......

If the top and bottom spars were solid alloy and the frame was heat treated AFTER welding .... then yes I'd say it's well worth the cash ... but the welds look cold to me which means they'd lack penetration and be brittle .... OK for motard and road riding ..... risky for dirt and off road ... forget jumping it at all ..... :p

If you want to know what truly properly done aluminium welds should look like .... take a good close look at the welds on an alloy fuel tanker truck .... then you'll realise that any alloy frame with welds that look any different should be steered clear of ......

Google Image Result for http://www.ieg-systems.com/naht2.jpg

This is what good welders aim for ..... the strength is in the peno and how well the metal fuses and wets in at the edges .... under cut weakens the the parent metal and over rolled edges indicate lousy fusion .........

picsofweldpenetration.gif


A full peno alloy weld plus other pics of high quality well fused alloy welds :

Fullpenobuttweldonaluminiumsheet.jpg


Alloywelding1.jpg
 
Flarry said:
And in reply to your other post, TJ russel managed to snap a motovert pro frame, dont know where/how it snapped though.
Click to expand...

Wasn't that a Motovert Expert frame ? Which looks very similar to the one this thread is about and is basically a Pitster type twin pipe frame made in alloy ........

snappedmotovertExpertframeTJRussell.jpg


I just noticed that the top tube was previously cracked nearly all the way around !!!!! The dark coloured parts are old and the light coloured parts are fresh .......... you can see where the lower tube tried to hang on but got stretched too far then let go in one clean break .......

snappedmotovertExpertframeTJRuss-1.jpg


The video (it copped a pounding though) :

YouTube - MOTOSnap!! 125!

Also check out what BBR says about welding broken alloy frames in this link under ... # CAN YOU PUT MOTOR X INTO CHASSIS Y? It's the absolute honest truth .......

BBR Motorsports, Inc - Browser Support Page
 
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