Motorized Bicycle Engine Kit Forum  


Go Back   Motorized Bicycle Engine Kit Forum > Motorized Bicycle > Motorized Bicycle Welding, Fabrication and Painting - The Chop Shop

Motorized Bicycle Welding, Fabrication and Painting - The Chop Shop Custom fabrication and projects, tanks, frames and more.

Thread Tools Display Modes
Old 11-29-2015, 01:29 AM
thxcuz's Avatar
thxcuz thxcuz is offline
Motorized Bicycle Elite Member
Join Date: Jul 2012
Location: St.louis
Posts: 288
Default Filling holes

Total noob question here.
My new years resolution is to learn how to weld. I'm getting an inexpensive arc welder from harbor freight and plan on practicing a lot before I make any attempt on a bike frame. One of the projects I want to tackle is giving a girls bike a sex change. If I cut off the bikes top tube and re position it, how do I fill the hole that's left behind on the seat tube?

I have a need for slightly increased speed

Last edited by thxcuz; 11-29-2015 at 09:29 AM.
Reply With Quote
Old 11-29-2015, 01:47 PM
2door's Avatar
2door 2door is offline
Super Moderator
Join Date: Sep 2008
Location: Littleton, Colorado
Posts: 16,224
Default Re: Filling holes

First thing that comes to mind would be to use a section of a seat post. It should slide down into the tube and cover the hole you make. Then, being very careful (you'll need some welding experience here) weld the post, where it shows, to the tube. This will do two things: Fill the hole but also reinforce the damaged area.

Good luck, and good luck with that HF welder.


EDIT: I've thought about this a few times today and it occured to me that there should not be a hole when you remove the girl's bike downtube. It is probably welded to the outside of the seat tube and when you cut it off it will not leave a hole but only the metal and weld bead.
A grinder should take care of that and you shouldn't be faced with filling anything.

Just be sure that you replace it with a top tube that will support the weight of you and the bike and is structurally strong enough. We've seen builders remove the top tube leaving nothing to keep the bike from folding in half but the down tube and bottom bracket. That won't work.

Age and Treachery Will Always Triumph
Over Youth and Skill & "Charlie Don't Ride"

Last edited by 2door; 11-29-2015 at 07:04 PM.
Reply With Quote

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

All times are GMT -5. The time now is 08:08 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2016, vBulletin Solutions, Inc.