pstock

I am having a devil of a time installing a rear wheel on a Bike Friday of mine.
some rears fit okay, others are a complete struggle, some are impossible

looking at the RH rear dropout it seems some axles are getting jammed as the dropout is not wide enough to accept it.

Thinking back I did bend the derailleur hanger about 10 years ago and had it straightened.
But I also never had to replace or remove the rear wheel in all those years (until today, when I had onto test whether my #1 wheel was dished incorrectly - that's another story)

anyway, one of the wheels I am installing to measure where it sits in the rear triangle will not seat fulling in the dropout.

measuring just now, the axle on the wheel I was struggling to install just now measure about 10.0mm
the axle on the wheel I normally use has a Dual Drive IGH and the axle (I notice now) has two flats on it. the Flats measure about 9.5mm and the other diameter of the axle measures 10.5mm (ahhh, yes the famous but scarce 10.5mm axle nut)

but my frame should take a standard 10mm axle.

so, is there any issue if I just file or drill out that dropout opening a bit?
seems less tricky than prying it open.

Andrew R Stewart 

All the Bike Fridays I've worked on (number more than a dozen) have used a "common" rear drop out based on a 10mm axle diameter. Between manufacture's tolerances, the industry using both 9.5mm (3/8") and 10MM diameters and things like paint thickness and incidents changing dimensions there can be situations where one wheel won't enter or fully seat into the dropout. If it is a paint or a slight closing up (and one measurement is worth a thousand assumptions) of the dropout slot then yes, filing the slot or paint slightly can be a good fix (and doing so only on the rear face of the slot to not affect the chainstay length and wheel alignment). Note the word "slightly"... What to avoid is also filing the top/seat face of a dropout as this will result in the wheel seating cocked, not in line side to side at the top and bottom of that wheel. This would look to the untrained eye as a wheel with a bad dishing (assuming the rest of the frame is straight).

But remember removing material from a nonreplaceable part (the dropout) needs to be VERY carefully thought through before going down that one way street. What I usually suggest is a slight filing of the wheel's axle end that won't fit as that is replaceable at far less cost than a frame repair or replacement. If the axle is keyed rotationally (as most IGHs are) clocking that filing is important to pay attention to. If the poor fitting axle were a threaded one (and I know in this case it isn't, but this serves as an example of what "slightly" is) the amount of filing on opposing points on the axle end is usually less than the thread depth. Like around half the depth.

Bending a dropout is also fine but (like filing it)thist can be another one way street if one went too far and the dropout broke. While it takes a number of bendings to work harden steel I tend to only do the minimum of this whenever possible. Not scared to do it but I rely on my experience to guide my in this work as I've seen the results of overly enthusiastic home jobs go bad before. Andy

delbiker1 

I have badly bent a couple of drop outs, steel frame sets. I do not have a lot of experience, but both times I used a bench clamp and arm strength to slowly, carefully get the drop out close to where it needed to be, stopping often to look at what was happening with the drop out. Then I used like a small cheater bar to do final adjustments. Both times they came out fine, but far from pristine looking. Adding one caveat, while the frames are nice 853 steel, they are well used, not worth a lot of dollars. Ergo, if the drop outs got destroyed, I would not have been happy, but okay with it, as the bikes were unusable without a fix. I might have made one of them a single speed just to keep it in use. I am still riding both bikes.

FBinNY 

Assuming, that the dropout was somehow bent inward slightly so the gap at the open end is too narrow, you can insert a lever and gently pry it back out so the sides are parallel again. Or, if you prefer not to pry, no problem using a file, but ONLY file the lower side, and again to get it parallel to the top.

If you're pulling out the file, you may also want to file a bellmouth into the lower side so it's easier for the axle to enter when you mount wheels. I do this to ALL my bikes, along with filing the lower tip narrower for the same reason.

pstock

Could you share a photo of what these mods look like?
I am not familiar with the term Bellmouth (and google is not helping me any)

FBinNY 

No photo, but picture the cross section of the end of a trumpet or funnel.

Kontact

Maybe I missed someone saying it, but the axle with the two flats is made like that so it can't rotate in the dropouts, which makes it challenging sometimes to slide the axle into the dropouts without the corners hanging up. You have to align the axle flats with the dropout slot and control the axle as it goes in.

grumpus

Both dropout slots should be the same width - if the drive side is closed up you really should bend it back into shape, rather than removing material. I'd use a large cold chisel to pry it apart, insert from the side and work it up and down while pressing in to "walk" the wedge between the sides until it's spread.