ALUMINIUM FRAME WORK

[stumpy]

HAS ANYONE BUILT A TRIKE FRAME FROM ALLY TUBES??? PROS ITS CHEAP AND EASY TO BEND EASY TO WELD.... CONS NOT SURE IF IT WOULD PASS A STRESS TEST ANY VIEWS ON THIS WOULD BE GOOD
STUMP

[triker_Chewie]

properly engineered i dont see the prob, lotsa sports bikes are ally

[Cabman77]

they used to make the space frames of formula 1 cars out of it just got to use the correct grade I would guess, and that might put you`re argument that it`s cheap out of the equation.

[nabsim]

Wouldn't this depend on whether you go hardtail or softail? I am thinking it would be more likely for ali tube to fracture on a hardtail but I don't know. Or does it just need better engineering nous to design a strong safe fram in ali?

[hornet6]

Its definatly a higher grade alluminium......not bog standard stuff on your average jap gsxr, R1,R6 race rep.     

[Dslam]

Hi Stumpy,
Here goes. This is my opinion on Ali tube framing and as my experience is limited (as is my intelligence) please treat it as such and I will happily bow to another who may have a better take on this than I!

Pure aluminium tube is a non starter as it will stress fracture and is too weak.

Aluminium alloys may be a better option but looking at the frames the Japs produce the dimensional increase required to create the stiffness required is immense. Bearing in mind the entire structure is computer designed and hollow cast, a home built welded tube design cannot deal with the stresses inherent with the use to which it will be put. I have discussed in the past the use of Ali structures for bike sprint frames with both frame builders and riders and the consensus of opinion is that the dimensional increase required to get the durability will end up being heavier that an equivalent mild steel one. The welds will need to be perfect also as some alloys change their molecular structure when heated beyond their design limits which will cause the weld to fail just outside the weld field. This became quite a discussion point when Reynolds '531' tubing was all the rage with frame builders. Although not an aluminium alloy it had the annoying habit of failing beyond the braze if it went over temperature during construction a matter of just 100 degrees. The points at which other parts would be attached would wear oval over time as the metal is soft and distorts with impact and vibration. Aluminium has a huge coefficient of expansion which means it grows with heat more than most other metals and transmitts heat very well which may cause additional problems. The Jap cast Ali frames vary in thickness throughout their length to help compensate for the above and to help transmit stresses.
In short, unless you are very competent in the welding and design departments I would stick with the more traditional materials.
Hope that helps. I need to lie down for a bit!!

[steve brock]

To achieve the same strength and stiffness of the frame it would look maahoosive,controls and brackets off the frame would be chunky too, anyway would you polish it, annodise it or paint it after ? Oxidisation could look pants after 5 minutes ... My two cents

[stumpy]

thanks for the input guys and yes over heated welded joints in any metal can lead to fractures not in the weld but in the material weather it tig mig or gas brazing i would not trust not saying its not a good way to join metal but feel its dated and the time and effort and cost of oxy accet puts me off gas welding ...any way ally seen many a trick bike frame fabricated in it it looks the bollox but every tube and bend is duplicate even trippled or 4 tubes is a single sided swinging arm guess i knew the answers but just wanted to write it off my build list thank you for pointing out the facts thou

stump

[Cabman77]

Hi Stumpy,
Here goes. This is my opinion on Ali tube framing and as my experience is limited (as is my intelligence) please treat it as such and I will happily bow to another who may have a better take on this than I!

Pure aluminium tube is a non starter as it will stress fracture and is too weak.

Aluminium alloys may be a better option but looking at the frames the Japs produce the dimensional increase required to create the stiffness required is immense. Bearing in mind the entire structure is computer designed and hollow cast, a home built welded tube design cannot deal with the stresses inherent with the use to which it will be put. I have discussed in the past the use of Ali structures for bike sprint frames with both frame builders and riders and the consensus of opinion is that the dimensional increase required to get the durability will end up being heavier that an equivalent mild steel one. The welds will need to be perfect also as some alloys change their molecular structure when heated beyond their design limits which will cause the weld to fail just outside the weld field. This became quite a discussion point when Reynolds '531' tubing was all the rage with frame builders. Although not an aluminium alloy it had the annoying habit of failing beyond the braze if it went over temperature during construction a matter of just 100 degrees. The points at which other parts would be attached would wear oval over time as the metal is soft and distorts with impact and vibration. Aluminium has a huge coefficient of expansion which means it grows with heat more than most other metals and transmitts heat very well which may cause additional problems. The Jap cast Ali frames vary in thickness throughout their length to help compensate for the above and to help transmit stresses.
In short, unless you are very competent in the welding and design departments I would stick with the more traditional materials.
Hope that helps. I need to lie down for a bit!!

wot he said

[stumpy]

haa lol pmsl well said cabby still laughing

[nabsim]

Jeez Dslam if that post is an examply of limited intelligence I will order a D cap and go and stand in the corner

[Dslam]

Don't tell anyone but I made it all up