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Discussion Starter · #1 ·
I was wondering if a pinned connection necessarily makes for a less desireable rim. Is a welded joint necessary for a quality build? There are quite a few rims out there that are pinned, rather than welded.
 

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Welded vs. pinned

John said:
I was wondering if a pinned connection necessarily makes for a less desireable rim. Is a welded joint necessary for a quality build? There are quite a few rims out there that are pinned, rather than welded.
Pinning and welding are simply two different means of accomplishing the same task. Each has its own advantages and disadvantages. Overall, I feel that if done correctly, a pinned (or sleeved) joint can produce a slightly better result. Too often, welding (and the subsequent necessary machining) can mask non-uniformity in matching the ends of the extrusion, or can induce distortions in the metal.
 

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Discussion Starter · #3 ·
I've been thining about hte annealing that takes place in the heat affected zone of the rim when welded. Rims are so thin, that even a tack weld will alter the strength of the aluminum. I've seen lots of tech stuff on the welding process, but nothing that idicates a heat treating after welding.

This, of course, wouldn't be the case with pinning (sleeve).....no heat used in the joining process.
 

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John said:
I've been thining about hte annealing that takes place in the heat affected zone of the rim when welded. Rims are so thin, that even a tack weld will alter the strength of the aluminum. I've seen lots of tech stuff on the welding process, but nothing that idicates a heat treating after welding.

This, of course, wouldn't be the case with pinning (sleeve).....no heat used in the joining process.

Annealing and heat treating are things involved in high carbon steels, not aluminum.
 

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Discussion Starter · #5 ·
Gee...then I wonder why there are so many alloys of aluminum out there???

That T number after an aluminum designation #( 7005-T6....6061-T4, etc)means "temper".....look at any material catalog....the tempers have a lot to do with strength. Whenver aluminum (or any metal) parts are welded...they anneal...or lose strength...in the area where the heat is greatest. These annealed materals can then be heat treated to restore some of the lost strength.
 

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Annealing and heat treating aluminum

fmw said:
Annealing and heat treating are things involved in high carbon steels, not aluminum.
You should check your facts before posting. There are many aluminum alloys that can be heat treated - including many of the alloys used for bicycle rims. A strong example of heat treating aluminum is the 6061 alloy used for bicycle frames (Cannondale and many others), which must be heat treated after welding to restore its strength, due to the annealling caused by welding.

All aluminum, whether alloyed or not, is subject to work hardening. Annealling works on any hardened metal, whether it was hardened by heat treating or work hardening.
 
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