olioli

Is there a mechanical reason for the internal step at each end of a headtube , or is it just a means to using narrow thicker walled tube ? Can I just use straight tube?

unterhausen

The frame is built and then the headtube is reamed to the correct dimension for the headset. The step is the end of where the tube was reamed, and it's not important. Not sure how you plan to avoid it though.

olioli

Hi , apologies I should have been clearer...I'm looking for parts to build into a wooden bike frame , and the ones I've seen online (ie Bear Frame Supplies) have a step already cut into them. I was just wondering if it was possible to use unstepped tube of the right dimension , and not need to ream it since there would be no heat being used that might distort it.

Canaboo

The problem is that tubing is basically not available in that interior dimension.

Nessism

...and even if there was the tube may not be perfectly round.

wsteve464

If you are talking about standard straight tubing specifically for head tubes you will need to ream it as they are slightly undersize to allow for distortion when brazing. Buy your headset and take it and the tubing to a machine shop. A bike shop maybe have the reamer but not the equipment to hold just the tube.

There are a couple of bamboo bike builders on here perhaps they will chime in.

Too slow

guy153

On the last frame but one I built I used a Reynolds 631 headtube with a 34mm ID for the usual 11/8 headset. It was supplied at the exact right size and didn't really need reaming. I sort of skimmed it a bit but hardly removed any material. I was a bit surprised by this as the Columbus HTs are deliberately a little small on the ID so you ream. But it seemed to work out absolutely fine.

It's just a plain gauge tube with no steps so you could use one of those.

unterhausen

I don't know how I feel about having the head tube be actual size. Haven't built a filleted frame in a long time, but last time I did filleted something together I got more distortion that I was happy with.

guy153

I was welding it and it did go a little bit oval but still averaged out to the right size and the cups went in fine. I was quite pleased because I only have a proper reamer for EC30 and was planning on seeing how I got on with a janky adjustable reamer (actually made in India surprisingly not China).