Hi. Is having a crank that has been cross threaded worth being fixed / rethreaded? I've pushed too hard and ruined right side. From Manchester UK if anyone knows a shop that does the work? Cheers.

Not to me. If I could get it to go on correctly without having to do anything special, I'd probably live with it till it became a problem. Might work fine that way for the life of your crank, pedal or bike. Otherwise, I'd just get another crank arm or entire crank.

Chasing threads removes material so I wouldn't want that. Others have chased the threads and probably worked fine for them. Helicoils work too, but that's a little involved for anyone that's a first timer doing that type stuff.

Have you tried threading pedal in from the rear?

Three summers ago I had a pedal loosen on a (funny coincidence?) UK made Raleigh GP and before I got home it was twisting in the crank.

Wrench at co-op threaded the pedal in from the back side of the crank, then screwed in as normal from front. Worked fine though I always wondered about it.

Last year my son took that Raleigh over and this spring sane pedal loosened again but this time I replaced the cranks because it was too far gone. I believe it might have been salvageable again if he'd noticed in time.

In theory a helicoil can be placed to repair the thread, such are made in R/L threading for bicycle cranks. It involves drilling a larger hole
with a specific drill in the crank and then tapping the hole for the helicoil and placing the helicoil. Some bike shops have this capability.
OTOH sq taper cranksets are pretty cheap for run of the mill bikes and it could be a toss up $ wise. Splined cranks (all cranks introduced
in the last 25yrs have been splined) would be a bit more expensive. In the US it is possible to order either a R or a L single crank,
sometimes name brand, others generic east Asian, and for sq taper these could be as little as $15-30.

As a general rule if the pedal can be screwed in from the back, the thread might be usable for a time, but cross threading of an aluminum
crank with a steel pedal removes 20-50% of the threading which means under pedaling forces it won't take long to trash the remaining
threads, as in WGB's experience. If only 2-3 threads are affected their is likely enough intact thread left to salvage by back side pedal
install or thread chasing with a tap. The latter should only be done by those with threading experience and the taps are not common
outside a bike shop.

A Helicoil will make stronger threads than the original aluminum ones. Helicoil installation is commonly done in new work where stronger more wear-resistant threads are desired than can be obtained in aluminum alloys.
Chasing threads can only reform the distorted thread form and help avoid future cross-threading, the weakness from displaced or missing metal will remain.

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...I do this repair here. Last time I checked, you could still get RH threaded helicoils (the ones for older spark plugs, when you strip the hole in the cylinder head.) But it varies with manufacturing trends, and there might now be someone making and selling the RH/LH sets again out of Asia.

OTOH, the tool set for overboring, rethreading the hole, and installing something called a "threadsert" (which appears to be stamped out of sheet metal) are readily available from a couple of sources, The threadserts themselves cost about six or eight bucks each. When you buy the tool set, it comes with a few sets.

It's not an hugely difficult job, if you remove the crank from the bike, hold it in a vise, and pay attention to getting it at a 90* angle to the crank arm. I'm sorry, but I don't do it for other people any more.I find working for other people to be a painful exercise in patience, which I have in short supply these days.

So I guess it depends a lot on the value of your crankset. I have a lot of older ones to which I am attached.

The Unior brand of bike tools includes reamer/taps to re-thread 9/16" pedal holes to, I think, 5/8 and matching inserts to get back to the proper 9/16". Both right and left hand reamer/taps are available with RH and LH inserts to match. Niagara used to sell this stuff and I've seen it on Amazon and Ebay as well, but don't know about current availability. My recollection is that the tools and inserts were a bit pricey, but perhaps a shop has the tools and the knowledge to do it at a reasonable price.

....I went back and reread this. If by right side you mean the drive side, that's RH threaded. So it's not impossible that you can get someone who works on cars and/or cylinder heads to install a helicoil like the ones they use for a spark plug hole repair. You want 9/16" x 20 tpi .

Thanks everyone. Taking it to a bike restoration shop today to take a look as have said they do helicoil. Surprised at how few places don't and have told me to get a new crank. Concerned about the strength but that appears mixed too.