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Cracking on older Aluminum Lugs

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Cracking on older Aluminum Lugs

Old 05-27-14, 07:51 AM
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MuchoMaas
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Cracking on older Aluminum Lugs

Hello everyone,
I posted this the other day in vintage but thought I'd also ask around here.

I picked up an early 90s Alan cyclocross frame, and just finished building it up for my gf to use as a city commuter. The frame seemed to be in great shape when I bought it, but I have now found two stress fractures in the seat post lug. This lug has two sets of "ears," one set on top for the binder bolt and the set below is were the seat stays bolt on. One fracture runs side to side beneath the binder bolt, normal stress from years of compressing the post I assume. But the second fracture really worries me as it runs top to bottom between the lower set of ears where the seat stays attach. Both are pretty small.
I have 0 experience with older lugged aluminum frames, let alone this threaded and bonding method that Alan apparently used. How concerned about these should I be? We don't have deep pockets right now so a full on replacement will probably have to wait a couple months. Does anyone have experience with similar issues and have a sense of how quickly these fractures might develop into a serious safety problem? Am I looking at a gradual decline or will the cluster completely separate while she's riding?

Thanks for reading!
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Old 05-27-14, 10:31 AM
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JohnDThompson 
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A picture would be nice...

Unfortunately, Alan frames do often fail at the lugs. Most often the head lugs, but sometimes the seat lug as well, as you discovered. Do the cracks extend all the way through the lug and the seat tube? Drilling a stop hole at the end of the crack can help slow its progression, but it has to be at the end of the crack to be at all effective. You may need to use a dye kit to determine this. Keep in mind that unlike steel, aluminum can fail very quickly and with minimal warning.
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Old 05-27-14, 10:42 AM
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MuchoMaas
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I found it difficult to see how deep the crack runs, due in part to the seat post having now become stuck after lowering a few cm. Interesting idea about drilling a stop hole... I will post a picture when I get home tonight.
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Old 05-27-14, 01:15 PM
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fietsbob 
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I had one a road got 2nd hand in trade for a re tubed and repainted and decalled Masi in 86..

and a cross super I got New from Mel Pinto Imports .. ( liked the road version better)

Shipping (air Freight) from the US was so expensive , although the repair once in Italy was quoted as Cheap, that I threw it in the recycle bin. sold the fork . to someone whose AlAn fork had cracks .

the CX forks were so lively the wheel shook in them an inch or more at the axle, when I put the canti brakes on ..

CX racing , slimy with mud it may have been better I sold the CX Super to someone else who raced Cross.. ..

Save your GF getting Hurt. .. Hang it up for Looks.. Or resell it to another victim.

For me circa 90-, all the components migrated to steel frames ..

still have 2 25.o Campag seat posts from them any Wants ? USE shims to use them in a 27 and a 27.2 frame were bought ,

a RB1 the 27.0 , a steel Pinarello CX is the successor , with the 27.2..

Last edited by fietsbob; 05-27-14 at 01:34 PM.
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