RIP to an old friend: The longevity of aluminium frames
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- Philip Whiteman
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RIP to an old friend: The longevity of aluminium frames
Does anyone have any wisdom about the longevity of aluminium?
After eight years of years of heavy usage, I have decided to condemn my Giant TCR aluminium and carbon hybrid construction road bike. I have heard in some circles that aluminium frames only have a life span of around five years due to corrosion and stress fatigue. Furthermore, my frame is a carbon aluminium hybrid frame whereby the tail is constructed of aluminium and carbon bonded together. On that score, I am not too sure about the long term integrity of a bonded construction.
Saying that, the only evidence of corrosion in the frame is to be found at the bushes surrounding the bottle holder threads. Yet, I am conscious that alu bikes are life limited because of the potential stress fatigue and fractures at the welds and at points of corrosion.
The actual reason for the withdrawal is due to the sheer economics of replacing the wheel set, bars, bottom bracket and entire group set for what is obstensibly an old bike.
After eight years of years of heavy usage, I have decided to condemn my Giant TCR aluminium and carbon hybrid construction road bike. I have heard in some circles that aluminium frames only have a life span of around five years due to corrosion and stress fatigue. Furthermore, my frame is a carbon aluminium hybrid frame whereby the tail is constructed of aluminium and carbon bonded together. On that score, I am not too sure about the long term integrity of a bonded construction.
Saying that, the only evidence of corrosion in the frame is to be found at the bushes surrounding the bottle holder threads. Yet, I am conscious that alu bikes are life limited because of the potential stress fatigue and fractures at the welds and at points of corrosion.
The actual reason for the withdrawal is due to the sheer economics of replacing the wheel set, bars, bottom bracket and entire group set for what is obstensibly an old bike.
A man who makes a habit of stamping pedals out of their cranks should probably swap his frame every season.
The rest of us can probably make an alu frame last more than 5 years. One hears scare stories about these 'modern' materials, but they often have a ring of urban myth about them, and I tend to take them with a pinch of salt. Anecdotal evidence (hearing of acquaintances whose frames snapped while out) makes me suspect that, in practice, they don't fail any more often than steel frames used to.
All the nasty 'snapping' stories I've read/heard have involved the failure of handlebar/stems, not frames.
The rest of us can probably make an alu frame last more than 5 years. One hears scare stories about these 'modern' materials, but they often have a ring of urban myth about them, and I tend to take them with a pinch of salt. Anecdotal evidence (hearing of acquaintances whose frames snapped while out) makes me suspect that, in practice, they don't fail any more often than steel frames used to.
All the nasty 'snapping' stories I've read/heard have involved the failure of handlebar/stems, not frames.
Re: RIP to an old friend: The longevity of aluminium frames
... but in reality a new one?Philip Whiteman wrote:... for what is obstensibly an old bike
- Philip Whiteman
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Re: RIP to an old friend: The longevity of aluminium frames
Over the past year, I have had three servicable bikes but in practice only ever used two. Therefore a third has been excessive and rationalisation is probably required.George wrote:... but in reality a new one?Philip Whiteman wrote:... for what is obstensibly an old bike
Last edited by Philip Whiteman on 21 Nov 2011 10:19, edited 1 time in total.
- Philip Whiteman
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- GrahamGamblin
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Aluminium does have a lower tensile strength than steel, however this is compensated for by using larger diameter tubing than steel-framed bikes to attain stiffness and strength. It is also more likely to be stressed by the welding process, so on a cheaper bike the joints may be weaker (more expensive frames can be heated and slowly cooled to strengthen the joint). Basically if you made an aluminium bike to the same design and with the same welding as steel, it wouldn't last very long, but the relative weakness of aluminium can be compensated for in the design and manufacturing processes.
Graham
Early aluminium frames did have a bit of a habit of cracking near the welds as it is a material that is tricky to weld and the process can reduce the area close to the joint to pure aluminium, which is an excellent conductor but has a tensile strength similar to that of marzipan.
The problem was solved by complete frames being heat treated after the building process. Hence artisan frame builders, by and large, abandoned trying to build in the material.
As Alan says, a Reynolds frame will last a lifetime, but it will be prone to internal corrosion in old age. However, this usually occurs around the bottom bracket and so the resulting failure is bloody annoying rather than dangerous.
The problem was solved by complete frames being heat treated after the building process. Hence artisan frame builders, by and large, abandoned trying to build in the material.
As Alan says, a Reynolds frame will last a lifetime, but it will be prone to internal corrosion in old age. However, this usually occurs around the bottom bracket and so the resulting failure is bloody annoying rather than dangerous.
- chris ankcorn
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I have just had my road/track frame, built by Bill Pollard of Coventry in 1947 ,renovated and resprayed [colour Magenta].
This is the fourth respray in it's long life.
Built of Reynolds 531, it was found to be in excellent, safe, condition when stripped to it's bare metal and carefully checked for integrity.
This is the fourth respray in it's long life.
Built of Reynolds 531, it was found to be in excellent, safe, condition when stripped to it's bare metal and carefully checked for integrity.
ALC
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alloy frames
For those concerned about the life of alloy frames, i believe that fatigue failures will always start with a hairline crack, which could be there for a considerable time before a fracture occurs. The point of this being that it is possible to buy a inexpensive crack detection kit. (about £25 ) that would do maybe 20 or so inspections. The one that i found on the web was from a aerospace company and is recomended for use on aicraft landing gear etc. It comes in 3 aerosol cans, a cleaner, a penetrating dye and a flaw finder. Very easy to use, first the cleaner, then the dye that will penetrate into the most minute of cracks, wipe the dye off and apply the flaw finder and any dye left in cracks will show up.
- Philip Whiteman
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1. Thanks Bob, that is really interesting. Where can these be obtained from?
2. The frame has been donated to Charles for renovation.
3. I vividly recall a very nasty accident on a club run caused by a fracture in a L shaped steel stem. Upon close inspection, I noted that only 2mm was fresh as the remainder of the break was rusty. The bicycle had been subject to an earlier collision and had been stored in the open air.
The accident occured near to Bredon Hill. The cyclist concerned was an American who was visiting another Beacon member. During the ride, the stem snapped clean into two, the rider lost total control and he landed head first onto a tarmac pavement with a sickening thud. He lost consciousness and went into convulsions. He was treated at A&E where he was diagnosed with minor but reversible brain injuries. The club run was instantly terminated and the 20 strong group returned to Birmingham in a state of shock.
2. The frame has been donated to Charles for renovation.
3. I vividly recall a very nasty accident on a club run caused by a fracture in a L shaped steel stem. Upon close inspection, I noted that only 2mm was fresh as the remainder of the break was rusty. The bicycle had been subject to an earlier collision and had been stored in the open air.
The accident occured near to Bredon Hill. The cyclist concerned was an American who was visiting another Beacon member. During the ride, the stem snapped clean into two, the rider lost total control and he landed head first onto a tarmac pavement with a sickening thud. He lost consciousness and went into convulsions. He was treated at A&E where he was diagnosed with minor but reversible brain injuries. The club run was instantly terminated and the 20 strong group returned to Birmingham in a state of shock.
Crack detection
Hi Philip, The failure that you described Is absolutely typical, as the crack had obviously been there for some time. When i was a lad and a steam train pulled into the station someone would walk along tapping the wheels with a hammer.If it rang like a bell it was ok, if the sound was more of a thud it denoted a cracked wheel and needed changing. But doubt if that would work on a frame. However the company that has the kits is. LAS Aerospace. www.lasaero.com
- Philip Whiteman
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Re: Crack detection
I am probably the only member of the Beacon who can proclaim to have undertaken that job. In my role as Carriage and Wagon Chief Examiner for the K&ESR during the early 90s, I used to tap wheels. Ultrasonic test kits were available at the time but were prohibitively expensive for a heritage railway. The tap hammer was effectively a small ball hammer with a very long handle. Fortunately, I never heard a thud. The major disadvantage was the inability to test tyres whilst the vehicle was located on a curve, not something that would have been a problem for ultrasonics. The only reason I had to withdraw wheels for re-tyring or lathing was usually due to the infamous flat.bobg wrote:. When i was a lad and a steam train pulled into the station someone would walk along tapping the wheels with a hammer.
Re: Crack detection
Blimey, if trains can't withstand the hedge cuttings there's no hope for us cyclistsPhilip Whiteman wrote:The only reason I had to withdraw wheels for re-tyring or lathing was usually due to the infamous flat.
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