Change my derailleur

Front and rear are separate systems, so no worry there. The big thing is whether you're running indexed(shifter moves between defined positions) or friction(shifter moves smoothly through the range)., With friction you can use pretty much anything. With indexed, the shifter + cassette + derailer must all match up.

But yeah, the Tourney should do fine. Although purists might sneer as such a long cage derailer on a road bike.

Thank you for the quick reply! So if I understood it well, I will be able to fix almost every rear derailleur, with these shifters!

[IMG]cyclingforums.com1000Open ↗[/IMG]

And what would you recommend? A long or short cage derailer?

The Shimano Tourney will work, but I recommend that you get a Tiagra-or-better rear derailleur because the Tourney is in sub-classification which is usually restricted to the least expensive OEM groups ...

A used Shimano XT 750 would be a much better choice than the Tourney, IMO.

ALL of my Road bikes have long cage rear deralleurs, BTW.

FYI. Looking at the finish on the lug-work (thin wall lugs with clean edges), that is-or-was a pretty nice frame ... at least, IMO.

BTW. The bike, as pictured, does have an indexed shifter -- it can be toggled into friction mode.

Quoted post said:

Originally Posted by iBram [IMG]/img/forum/go_quote.gif[/IMG]

Thank you for the quick reply! So if I understood it well, I will be able to fix almost every rear derailleur, with these shifters!

[IMG]cyclingforums.com1000Open ↗[/IMG]

And what would you recommend? A long or short cage derailer?

With the shifter set to friction, it'd be a bit of a challenge to find a derailer that wouldn't work. It's possible that something out of the SRAM family would come up short.
With the shifter set to index, the majority of the Shimano family would work.
There are some old oddballs, Dura-Ace, Positron... and some newer stuff that I'm not familiar with. But at a guess something like 90% of the product range should work.
I'm usually not too concerned with appearences, and will happily use whatever that's handy to get back on the road. But I wouldn't turn a short cage down, if it would suit the gearing range I wanted from the bike.
Long cage stuff is more common, and there's not much of a downside to it.

Quoted post said:

Originally Posted by iBram [IMG]/img/forum/go_quote.gif[/IMG]

Someone gave me an old racing bike because he broke the rear derailleur, and didn't want to take it back home. So I looked at the prices of a derailleur, and I decided to replace it! I did some research on the internet, and found that not every derailleur will work on every setup. So I decided to look which setup I currently have, and it is the Shimano 500 EX (shifters, 2 derailleurs). Now I can't find anything about replacing only the rear derailleur, with a new version of it.
I've found the Shimano Tourney TX51, will this one work with a 500 EX front derailleur, and the 500 EX shifters?
On my rear wheel I have 7 gears, and the on the front one I have 2.

Can someone tell me if it will work?

If you need more information, you can ask!

BTW. The 'Shimano 500 EX' shifters/etc. (if they aren't actually "Shimano 600" shifters/etc.) are the immediate predecessor to the just alluded to Shimano 600 component group ...

• the Shimano 600 was renamed as 'Ultegra' (c1998) ...
  
• Ultegra is the component level just below Shimano's top flight component group (i.e., Dura Ace) ...
  
• that said, dabac is absolutely correct that for the most part, the difference between Shimano rear derailleurs is often cosmetic AND most can be interchanged for another ...
  
  

The problem with the Shimano Tourney rear derailleurs (unless I am mistaken ... and, THAT is always a possibility!!) is that the design is very primitive (a vertical parallelogram which is attached to an intermediate hanger) and the over-the-counter price is only a little less than the Shimano derailleurs which are based on more contemporary (based on SunTour's "slant parallelogram"😉 engineering ...

And, a 'used' Shimano rear derailleur which you could buy via eBay will probably cost less & be much better than a new Shimano Tourney rear derailleur ...

So, 'I' would try to limit the choice of a replacement rear derailleur to almost any Shimano rear derailleur which is designated as a 8-/9-speed Shimano-compatible because it should be compatible with your current shifters when used in index mode + most future combinations which you may want to use ...

• BECAUSE (this is starting to get into the weeds ...) the pulleys are narrower on 8-speed-and-later rear derailleurs than on most 7-speed-and-earlier rear derailleurs