Aluminum (6061) frame dropout squeeze

Question

I have a bicycle with a 6061 aluminum frame. I had to replace the rear wheel, and I bought a wheel with an axle length that is a few mm short for the dropout spacing.
In order to fit the axle into the frame I would have to "squeeze" the dropout about 4mm. Currently the outer dropout of the frame is 144mm, and everything seems to fit if I squeeze it down to 140mm.
I have already ordered a longer hub axle, but it will be at least 2 weeks until I get it, and I would like to ride my bike with the squeezed frame until then. I know that in general, it is not a good idea to bend or even squeeze aluminum frames, but I am not sure those measly 4mm will make that much of a difference.
So, my question is:
Considering this is an aluminum frame, will the 4mm dropout squeeze cause damage in the long-term or maybe breakage? How safe is this?

Grigory Rechistov · Answer

It will damage the frame long term, or rather shorten the life expectancy for the rear triangle. Short term… it depends how short the term is.
Wheels are typically have standardized widths, as are frame's inner distances between the dropouts made to match them. Unless the frame is already damaged and bent or has a manufacturing defect, as the comments above suggest, you are likely trying to squeeze a 130 mm road hub wheel into a 135 mm MTB-frame (or maybe a 135 mm MTB wheel into 147 mm Boost-QR? does not matter, really)
Note that you may also have problems with adjusting the rear derailleur, as the cassette will also be off its intended position. It may not be possible to shift into the biggest rear cog.
If I were stranded somewhere far from proper components with only a 130 mm wheel to have, I would rather have attempted to add some sort of spacers taking up 2.5 + 2.5 mm at either side of the wheel, rather than compressing and stressing the dropouts.

Aluminum (6061) frame dropout squeeze

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