Aluminum Frame Longevity

Discuss light weight issues concerning road bikes & parts.
boolinwall
Posts: 195
Joined: Thu Aug 23, 2012 11:19 pm

by boolinwall

It's worth noting that very few companies know aluminum like Kinesis. Yeah, they don't have the pedigree behind the name, but the quality's there. Plus,, the best alloys on the planet are useless in the hands of the wrong welder. Take too long to weld a joint and you'll compromise it.
Being in Sweden, you must be familiar with Principia? These guys were the masters of aluminum welding. They'd even allow you to send your frame back after awhile to get re heat treated to put the snap back in it. Too bad they had awful financial management though. I'm not convinced the current Principia are quite what they used to be.

by Weenie


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by User Name

DMF wrote:This is a 51cm ST/53,5cm ETT frame though, the 58cm ETT equivalent is in the 1.800+ grams range... Not that I'm concerned though, I like my porky little girl, which would make it a shame to retire her :)

But weights aside, I reckon there is some truth to the quality of alloys used, that might contribute to the frames fatigue, or time before it goes soft, or is there not? Is all 7005 created equal, for instance?

I would regret to spend three or four times the cash of this one (say a Caad or Allez) and only get three good years out of it... That's an individual number ofcourse, but seeing as my case is my case so...

Ah yeah, i suppose that is a little beefy. My old 57cm Specialized Allez Comp was 1730g, and man, I loved it. It was my first alu frame, and it was beautiful: stiff enough, yet smoooooth in all the right places.

I'm not too techy when it comes to different alloys of alu. I was always told that the mid-range, brand name alu tube-sets were stronger than the generic, heavy stuff, but I dunno. I couldn't imagine busting one of those cheap 1900g Gitanes unless I ran over it :D

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DMF
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Location: Sweden

by DMF

Yes, quite fondly remember Principia (but they were Danish though, weren't they?). Never owned one, but aspired to some years back...

Glad to hear Kinesis are in the ballpark, but sadly that might put aluminum out of the equation all together for a new frame. Steel it is then :)

boolinwall
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Joined: Thu Aug 23, 2012 11:19 pm

by boolinwall

Yes. Principia are in fact Danish. I have a Boreas frame kicking around somewhere. It was made by Principia. Or at least designed by the same people and made from the same alloy. Either way. Amazing stiffness, good weight, and not as harsh as you'd expect from a frame that rigid.

mickey
in the industry
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by mickey

re: frames "getting soft"

Here's the consensus on alu frames starting to "feel soft" when I've polled some of the better known alu frame builders and big 5 co. design engineers:

(Experientialy) about half of us think there's something to it, half of us don't. None of us can think of ways to rig up a test rig to figure it out. Basic laws of metallurgy don't really give us a yes or no answer.

When I'm fit I'm a 1700+ watt sprinter. I maybe sorta-kinda "notice something going on" over the course of a few years on a really light frame- sometimes, but mostly when my self-esteem is low.

I have a 16 year old dirtjump frame that still seems crispy fresh...
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boolinwall
Posts: 195
Joined: Thu Aug 23, 2012 11:19 pm

by boolinwall

I actually giggled there. The 16 year old dirt jump frame still feels fresh because it isn't cycled nearly as much as a road frame. By "cycled" I mean that each pedal stroke under load is a "cycle". These add up over years of road riding. Picture 80 RPM's over 4 hours of use, every week for 5 or 6 years. Combine that with the tube walls on your dirt jump frame being at least twice as thick. Yeah,, I'm not surprised it still feels great.

boolinwall
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by boolinwall

And props to an industry guy being on here giving his two cents worth Mickey. It helps everyone when folks in the know help. As apposed to guys like myself who've just spent years studying others results instead of testing them himself.
Basically, I'm saying,, you have more first hand knowledge than I could ever hope to have.

MarkTwain
Posts: 168
Joined: Sat Feb 23, 2013 10:51 pm

by MarkTwain

boolinwall wrote: Basically, I'm saying,, you have more first hand knowledge than I could ever hope to have.

Then why poo poo his post? :noidea:

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btompkins0112
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Location: Mississippi

by btompkins0112

Yeah, bit of double-talk. The dirt jump frame also.....wait for it.....jumps dirt. Lot harder use than the typical road bike. Not to mention, I would guess that Mickey spends a lot of time shredding his dirt jump bike. Just sayin'.


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justkeepedaling
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by justkeepedaling

Yeah... That dirt jump bike is probably taking loads that are at least quadruple of "pedaling at 80 rpm" regularly.

boolinwall
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Joined: Thu Aug 23, 2012 11:19 pm

by boolinwall

I wasn't poo-pooing his post. Just saying why I thought a DJ frame would feel different than a road frame.

MarkTwain
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Joined: Sat Feb 23, 2013 10:51 pm

by MarkTwain

Fact is, both are built to the specifics in which they are ridden.

Comparing the two is besides the point. The question was longevity of aluminium, to which Mickey gave his experience and stated examples.

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DMF
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by DMF

Surely the DJ frame note was just there for giggles? If It's about cyclical loads, then no DJ frame sees even 1% the amount of a road frame of those, not even in a decade, or two...

And, take this from a guy who did nothing but ride bikes (didn't even work, couldn't find the time) thru the grand "Go BIG, or go Home" era of Freeriding, these frames really only take a pounding when you either tank the landing or go beyond your abilities.

Ofcourse both happens, but really not as often to justify calling it cyclical loading. Most DJ landings are a pretty smooth affair once you get the hang of it... and when DJ frames break, it's seldom due to actual fatigue. It's like banging a hammer on a kitchen table until it breaks and call it fatigue...

Pugrot
Posts: 62
Joined: Wed May 12, 2010 11:52 am

by Pugrot

Out of interest what's the best source of technical information about the different grades of aluminium and heat treatment requirements, must be a bit out there given it's prevalence in aircraft?

I had a shot at aluminium TIG the other day and struggled bad to lay down a single decent bead on a flat plate, let alone in 6G which most bike welds seem to be. Full respect to anyone who can manage to wrap perfect beads around thin wall tubes and then have them head out the door for years of abuse.

by Weenie


parajba
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Location: London, United Kingdom

by parajba

Interested to hear your opinions on my Caad9 purchased 4 years ago. I've done around 45,000 km on it (99% commuting though London), went through 1 chainset at around 35,000 and several wheelsets. Very well looked after.

Time to replace the frame? I'm 69kg.

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