Does re-plating a part make it weaker?

[WillWork4Parts]

You could answer your question by simply taking a file to test the metal surface hardness. I do not believe they were case hardened.

Hardening would cause another set of problems. Hardened metal breaks "clean", think the way glass breaks.

Just a thought.
John

I do believe the ten speed varsity cranks were tempered. This is going off of memory from what a shop owner told me back in the early 90s.
I tried confirming with ads, but this is the closest I could get starting with a 77 Varsity sport.

The cheap 10sp Varsity bikes I could find at a salvation army got robbed for their cranks and definitely took a beating better than the standard issue one piece cranks of that era. They had a diamond shaped cross section.

 

[Schwinn Sales West]

I do believe the ten speed varsity cranks were tempered. This is going off of memory from what a shop owner told me back in the early 90s.
I tried confirming with ads, but this is the closest I could get starting with a 77 Varsity sport.

View attachment 1777394
The cheap 10sp Varsity bikes I could find at a salvation army got robbed for their cranks and definitely took a beating better than the standard issue one piece cranks of that era. They had a diamond shaped cross section.

When BMX was starting, we used the 27" Schwinn cranks when building up custom BMX framesets. The 10-speed Schwinn cranks were 1/2" longer, had a stiffening rib (diamond shape crank arm) which I attributed, but maybe they were also hardened. I never saw one bend or break that was not backed over by a car in the driveway. Eventually, everything went very light in weight for BMX racing.

John

 

[lordscool]

They use acid to strip them so it very possibly makes them weaker.

 

[ian]

When Steve called me about this I was shocked-this doesn't happen that often. The first thing I asked was he standing up on the pedals/off the seat......answer=yes. In every incident of a busted crank I have heard of this was the culprit I feel. I am sure the above mentioned re-plating changes have something to do with it-but the drop forged crank after 75/80 years use and designed around an 80/100 pound kid may have some merit. When my dad was a kid his crank broke and a very sharp shard cut him across his ankle and up his leg. He joked he doesn't know how he made it home without bleeding to death-still had the scar-nasty one too. On some of the rides I go on with other riders they must be thinking-'that old guy can't keep up' because every hill/upgrade-I get off and walk my bike uphill. I never stand on my pedals. Just my opinion........

I do the same uphill. I dinna wanna break a chain either.

 

[Schwinn Sales West]

I do the same uphill. I dinna wanna break a chain either.

I call it, SELLING the idea.

I'm in the same age group as you guys so don't think I'm picking on just the old grey hair, no hair guys. When we get to the hills, or a rise in the road, we all get off the bike and then tell the younger stronger guys it's because we are concerned about breaking a chain or a crank. When we were younger, it was always a sprint to the top.

Our views change over the years, it's no longer important to be the KING OF THE HILL.

John

 

[Thee]

When BMX was starting, we used the 27" Schwinn cranks when building up custom BMX framesets. The 10-speed Schwinn cranks were 1/2" longer, had a stiffening rib (diamond shape crank arm) which I attributed, but maybe they were also hardened. I never saw one bend or break that was not backed over by a car in the driveway. Eventually, everything went very light in weight for BMX racing.

John

YUP DIAMOND CRANKS 😀 !!! 7 1/2 “ BMX OLD SCHOOL !! NICE !! we’d scrap a whole bike for them back in the day

 

[Thee]

They use acid to strip them so it very possibly makes them weaker.

Original vs Restore ? I put new chromoly cranks on my BMX cruiser builds so they don’t break and make me Eat S*%T ! I can do that just fine without a catastrophic part failure 😆😂🤣

 

[ian]

I call it, SELLING the idea.

I'm in the same age group as you guys so don't think I'm picking on just the old grey hair, no hair guys. When we get to the hills, or a rise in the road, we all get off the bike and then tell the younger stronger guys it's because we are concerned about breaking a chain or a crank. When we were younger, it was always a sprint to the top.

Our views change over the years, it's no longer important to be the KING OF THE HILL.

John

My hair is "antique blonde" , not grey..... 😀

 

[Thee]

My hair is "antique blonde" , not grey..... 😀

Hey you kinda stole my line @ian lmao - Brushed Nickle hahahaha