replace derailleur hanger or buy alignment tool

What he said 👆

Ah, ok. Don't know where to go for it over there. Presumably Park Tool is rather expensive over there too, there are a lot of cheaper brands that will do the job just as well. It's basically a long stiff bar with a bolt one end to go into the hanger and an adjustable pin at the other end to gauge alignment. Do look at the reviews, I wouldn't buy a 1 star rated product. But I also wonder how many bad reviews are down to user error. When using an alignment tool try yo measure to the same point on the wheel so you are getting a true comparison, unless you know your wheels are completely true of course. Only bend the hanger a little at a time, they are designed to break before anything else so are an obvious weak point. I bought a spare hanger with my bike, haven't had to replace it in 10 years, but have straightened it a couple of times. I got a Cyclus one, it's not great, the pin could be longer, but it certainly does the job.

Replacement hangers can be cheap, but not always. However, as you say they are always cheaper than an alignment tool.

In all the years that I had 7-speed, 9, and 10-speed gears I never needed an alignment tool. The alignment required for good shifting is not as critical. But as you cram more gears onto the hub, they get closer and closer together. Therefore, the precision of the shift needs to increase (even allowing for wider hubs).

When I got my first 11-speed, it was a 1x and had a big range cassette, so at times, the lower mech arm hung low and collided with trail debris. The impact can sometimes affect the hanger but without breaking it. On occasions my shifting would go out and no amount of my usual tuning would restore perfection. My LBS fixed the problem for £10 and it didn't take them long. I later discovered that they used an alignment tool.

My first 1x12 speed bike followed and I always seemed to have shifting problems. That 51-tooth cassette was really big and the mech arm was in harm's way. After two visits to the LBS at £10 per go I discovered that they used an alignment tool. So I bought one, learned how to use it off YouTube and fixed the next one myself. But this time instead of it being +/- 3mm as per instructions I spent another 5 mins and got it as spot on as I could measure. As luck would have it, I never had another alignment problem with that bike. But I use the tool now on a new bike just to make sure that everything is spot on to start with. In addition, I have used it on my grandson's various bikes as he is always catching the mech on something.

On subsequent 12-speed bikes I have broken the mech in half right through the body, once on one bike and twice on my current bike. I was lucky to avoid wheel and frame damage. Each time the cause was snagging on a Pine sapling; boy they are tough! When the new mech arrived, it would have been unwise to just bolt it on without first checking that the hanger was OK.

I buy a spare hanger for each bike new to me and I carry it in my pack, just in case.

I bought the Park Tool version, it cost me about £50 and I have had more than my money back in avoided charges from the LBS, plus the avoidance of hassle in transporting the bike back and forth. Getting the bike back on the trail more quickly is a big bonus too. In addition, I have the satisfaction of knowing that the bikes are spot on and that I did it.

I have the Wiggle Lifeline alignment tool and it works well enough to sort out bent hanger problems.

It does have a bit of play in the joints but you can adjust for that.

Maybe the Park tool is a lot better - maybe not - but the cheaper tool certainly allows you to do the job.

I just bend the hanger until it looks straight, never had any problems with shifting. I have found that the aluminium is soft enough that you can do it by hand.

The top pulley is pretty close to the sprockets, the hanger would have to be way out to make a noticeable difference to the horizontal movement.

Align it if you can, but maybe carry a spare in case it gets a knock and breaks.

There's a company on Ebay that seems to specialise in unbranded hangers, cheap to get a spare , we do a bit of touring/bikepacking, handy just in case.