Unique features on my 90 Yo

mkozaczek

New member
I finally got around to building up my 1990 Yo and am curious about what look like some reinforcing welds around the headtube and seat cluster. I'm not the original owner of the bike, but the paintwork appears original and it even has a sticker from the bike shop I'm assuming sold it (I suppose it could have been traded back at some later point though). So, these seem like factory added welds. Also interesting to note that it lacks the Fat Chance decal on the seat tube and instead has the Team Yo decal and also no American Flag sticker on the chainstay.

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I-ROBOT

New member
Hello

Nice early YO, and that is the explanation!

All Yo Eddy's have inserts welded into both ends of the head tube and the top of the seat tube. On the early models, we left the welds as is.

I made rotating fixture that spun the parts while I held the torch over them to join the inserts to the tubes. The first few head tubes were welded by fusing the inserts to the tubes but we had cracking issues since I was not adding any filler metal and the rapid cooling rate of the fusion welds would cause the 4130 to harden and the welds were cracking. We fixed some of them by rewelding them with the same filler metal that we used on the remainder of the frame welds and the issues were solved. It's possible that the frame you have was returned and repaired under warranty.

I kept tweaking the weld parameters and figured out how to add filler metal and make the welds much smoother on the later models.

The seat tube inserts were welded in the same fashion. If you take your seatpost out, you can take a coat hanger or other metal rod and stick it in the seat tube and you will feel the edge of the insert.

This was done to provide extra rigidity in the seat stay area and to be able to use a light-weight seat tube that would otherwise not be strong enough in the seat stay area and to be able to resist cracking from repeated loosening and tightening of the seat clamp.

Hope this answers your questions

Good Luck with it
Scott
 
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