Builder question: Steel frames & vent holes

[Mike748]

I took my newly acquired '85 Paramount apart to Frame-saver it (even though the tubes look like they just left the factory!) and noted that this frame has an abundance of vent holes: 2 in the seat stays, 1 in the chain stays, 2 in the fork blades. Made applying the frame saver easy (and messy).

In contrast, my '96 CSi has no vent holes anywhere.

Is the difference just builders' choice? Do the tubes come pre-drilled from some makers (in my case Columbus on the Paramount, CCL which I think is Reynolds on the CSi) or does the builder drill them?

If you don't have a vent hole, doesn't that make brazing difficult as the hot air inside the tube will cause voids or some such as it cools? Or do some builders fill the holes after brazing?

[David Kirk]

I think every steel builder uses vent holes of some sort for the reason you mentioned............. if you don't have them the air pressure builds inside the tube during heating and tends to blow the molten brazing material out onto your shoe. So a small gas hole will prevent that.

Main tubes on bikes usually have vent holes hidden inside. Say for instance the hole in the seat tube that is hidden by the top tube and likewise on the head tube. This allows for air expansion, the removal of the flux from inside of the tubes and the application of framesaver inside the tubes.

The the seat stays and fork blades have no where to vent out to so they have small holes drilled directly into them. You can see these on some bikes as they are left open. I've never been a fan of the open holes myself and I take the time to fill them. I feel this looks better as well as assures no moisture can get in. That said lots of nice bikes have the holes left in there and they last for decades. Go figure.

I hope that answers your question.

dave

[Mike748]

Thanks Dave, that's what I figured. Very nice touch to have the holes filled in... but how do you fill the holes?

[David Kirk]

Thanks Dave, that's what I figured. Very nice touch to have the holes filled in... but how do you fill the holes?

I lil' dollop of brass and 30 seconds of sanding and you'd never know it was there.

dave

[Erik.Lazdins]

I lil' dollop of brass and 30 seconds of sanding and you'd never know it was there.

dave

I love the Roman numeral as it is exceedingly classy, much like your bicycles! :beer:

best,
Erik