I have a rear dropout that was bent due to an accident. It was bent on the derailleur side and I'm wondering if it's dangerous if I hammer it back into shape. It doesn't appear to be bent laterally, as far as I can tell.

Thank you!

I would put a piece of pipe over the end and gently bend it back. I would not hammer on it.

I would not use a hammer or BFH! The non drive side doesn't look too good either. What do you have to lose? I would protect the surface and clamp from the stay joint to the end of the DO and squeeze. Be prepared for failure. I don't know the process for creating this part so can't opine a prediction! Can't be a casting or it would have failed!

Or grasp it with Channel Locks from the backside and try to clamp it closed a bit at a time. I've done that.

Can't tell if that is a stamped or forged steel dropout, If it is stamped plate steel, you can mos likely do the fix yourself. Steel plate is very forgiving. You can hammer it back to shape but do it gradually so the steel's malleable properties will work with you and you can avoid causing cracks. Once you have it back straight, check really close for any cracking. Best to take off all the paint at the affected area to do so.
If it is a forged dropout, it will be harder to fix as it will be thicker/stiffer and heat will most likely be required to avoid cracking it. Applying heat to such critical parts of the bike which can have its brazing adversely affected, should really be left to a frame builder/specialist..... then you have to ask yourself how valuable is the frame and is it worth having to spend such money to fix it.

I'd try to bend it back with a soft hammer, clamped with a 3/8" bolt and nut with 2 large thick washers to keep it aligned.

+1^^, definitely the alignment is a big issue, keeping the flat surfaces in-plane to avoid all added stress in the metal.


Due route's (sp, I know, thanks to auto-correct) pipe idea also seems valid, particularly if a good-fitting pipe happens to be at hand.
1/2" galvanized pipe perhaps?
Or possibly a smaller size, squashed into more of an oval shape?

Think this through, assessing all of what tools/equipment that you may have at your disposal!
Rush it and ruin it I always say.

I will add that possibly gripping the bent lower with a bench vice could allow a controlled re-bending.

Aligning such dropout lower tangs laterally shouldn't be too hard, I bet that in some cases, you can do it by hand, if you have strong fingers......
Doing so will give you most control and avoid bending it too far one way or the other..... You shouldn't "overthink" the fix on these simple (if this is indeed a stamped steel dropout), old bikes....

+1, I've bent back even forged dropouts (not as open like those though).

Looks like a stamped dropout, so bending it back with a pipe or Channel-lock pliers as suggested ought to be ok. The good news is that it doesn't have an adjuster bolt hole, which is a common failure point when bending dropouts.

USPS did a number on a 753 Raleigh SBDU frame I received about 15 years ago. The frame was perfect except for the driveline side dropout had now been closed up to about a 1/4" opening. I was told cold setting would work if careful. It didn't. Dropout fractured right at the adjuster screw hole.

So it sits out in the barn waiting to be sent out for repair. I'll get around to it one day.

Since you don't have the adjusters and it's stamped there's a pretty good likelihood you will be ok. Just go slow and easy. I like the bolt and washer alignment idea.

Good Luck!

Yup, the adjuster raises red flags when I run into this.

The stamped drops on the OP's bicycle should bend right back into shape. I do it by supporting the drops with the suggested bolt idea and then clamp the drop in a vice and, with great care and checking progress frequently, squeeze back into shape.

If the drop is forged with an adjuster, I forget about it. My butt is just too important, no buts about it.

Piece of pipe, like was suggested above has worked for me. If there is a hole for an adjuster screw, I put one threaded all the way in. The first time I didn't, and the hole became too deformed to ever put one in again.
Go slowly.
Good luck, Eric

I use to clamp those in a vice to flatten 'em out them manipulate as needed and reclamp.. back n forth until it was good.

One thing I would do in conjunction with gently bending it back into shape is find something round and sturdy, like a ratchet handle or socket wrench extension, that exactly matches the radius of the nominally intact dropout. Use this as a mandrel in the U of the distorted dropout while you are persuading it back into shape. It would also be good to constrain the bottom of the U laterally with a C-clamp or adjustable wrench, so that it stays flat while you reshape it longitudinally. You probably need a buddy to lend an extra pair of hands, in order to do everything simultaneously.

What have you go to loose? I'd put the bottom end of the dropout in my bench vice and use the rest of the frame as leverage and bend it down nice and slow.

Thanks to all for your input!