Steel frame - Alloy seatpost - Minimum insertion?

badgerjockey

I have a steel road bike - Genesis Equilibrium 20, which was bought second hand after someone custom built it.

It looks like they used their old Ritchey V2 seatpost in it which had approx the bottom 5cm cut off it.

I also discovered an ever so slight bulging of the seat tube on the frame an inch or two down from the top tube-seatstay junction. Is this normal or cause for worry?

They way I have the seatpost setup at the moment gives me an insertion into the seatube of about 9.5cm.

Any thoughts would be great.

H

Monty Dog

3-4 x seatpost diameter minimum is recommended, well below the toptube junction. If the bulge is all the way around then the tube is probably externally butted to give it extra strength in this area.

badgerjockey

You're right, there is the distinct possibility this is just the butting junction... But, 8.5cm is really toward the minimum of the minimum insertion. I am an 80KG rider and might start to use a saddle bag too...

Monty Dog

Depends on how much is sticking out the top too - but as you've noted, the seatube is reinforced. More a problem with 400mm ultralight carbon posts sticking out of compact frames TBH, with a steel frame and a robust alloy post, shouldn't be a problem as long as the post extends below the butted section.