Bent triangle
- Thread starter ILoveMyElectra209
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three steps.
First is the "string method" for checking the alignment and rear drop out width.
Second is getting the dropouts parallel to each other.
Third is the chain line.
Everything you need is at the Sheldon Brown page on frame alignment. Pictures included.
https://www.sheldonbrown.com/frame-spacing.html
These cheap gas pipe frames are the easiest to realign. Some get (oopsie) bent when someone drives the car in to the garage and squeezes the bike up against the wall.
Aluminum and carbon fiber frames are not straighten-able without destroying them for good. Cromo frames are so much stronger it's hard to cold set them.
I respace and align several frames every year. Some due to damage, mostly because I do a lot of single speed conversions on derailleur bikes. . Respacing a frame to fit a hub vs adding spacers to an axle to fit a particular frame. Just depends on the frame construction & hub. Most single speed hubs are 110 mm wide, most 10+ speed bikes are 121, 126, 130, 135mm wide. Adding too many spacers means more axle flex and possible breakage. Some frames are just too difficult to respace well.
First is the "string method" for checking the alignment and rear drop out width.
Second is getting the dropouts parallel to each other.
Third is the chain line.
Everything you need is at the Sheldon Brown page on frame alignment. Pictures included.
https://www.sheldonbrown.com/frame-spacing.html
These cheap gas pipe frames are the easiest to realign. Some get (oopsie) bent when someone drives the car in to the garage and squeezes the bike up against the wall.
Aluminum and carbon fiber frames are not straighten-able without destroying them for good. Cromo frames are so much stronger it's hard to cold set them.
I respace and align several frames every year. Some due to damage, mostly because I do a lot of single speed conversions on derailleur bikes. . Respacing a frame to fit a hub vs adding spacers to an axle to fit a particular frame. Just depends on the frame construction & hub. Most single speed hubs are 110 mm wide, most 10+ speed bikes are 121, 126, 130, 135mm wide. Adding too many spacers means more axle flex and possible breakage. Some frames are just too difficult to respace well.
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I have both versions of that park tool but a 2x4 works better for overall alignment. (different hook sizes) I only use the two park tools (at the same time) when I'm trying to bend a stay mid-stay without bending the stay at the bb a the same time. If you use the park tool you need something to leverage against. Just having 1 park tool only works if you have an immovable anchor for the frame. I've broken 4 bench vises in half trying to remove bb cups, etc, and my bench (with the vise) isn't rock solid.
With the 2x4 you use the floor and gently step on it. Worse case you have to lift the 2x4 and have the wife stand on the frame to hold it down.
With the 2x4 you use the floor and gently step on it. Worse case you have to lift the 2x4 and have the wife stand on the frame to hold it down.
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I’ve used hardwood blocks on the cement basement floor to keep the bent part elevated, a 4x4 placed under a basement beam, a horseshoe shaped hardwood block to clear areas that aren’t bent and a small hydraulic jack to press the frame back. Sometimes you have to bend it a little in the opposite direction before it springs back straight. You can make it straight and leave it for a few days to see if it’s going to spring back before trying to bend it opposite. Go slow, avoid dents by spreading the force with another hardwood block or a piece of angle iron. I no longer have a basement so I made this contraption.
Homemade tools to determine if the frame is aligned.
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