Hello bike forum mechanics,

I have a trek 1500SLR, not exact on the date. Looks exactly like this one, except for no discovery channel decal. https://www.trekbikes.com/us/en/bikes/2006/archive/1500

Long story short, I crashed and bent the rear ultegra derailleur beyond repair (according to LBS). I would like to purchase a used and working rear ultegra for the LBS to install, because they only carry the new 10spd ones.

Does anyone know which Ultegra rear derailleur I must purchase? I asked a buddy and he said I must factor in amount of gears and chain length. I would just like to purchase that same one that came stock with the SLR, which should theoretically fit without a problem.

Any advice or links to sellers would be awesome!

Thank you bikeforums!

From the Trek catalog you referenced your bike came with an Ultegtra RD-6500 long cage rear derailleur intended for use with a triple crank, which it also has. So you can use any 9 or 10-speed Shimano long cage road derailleur. A 105 will do just fine and you don't have to stay with Ultegra.

Thank you HillRider for the speedy reply! Any idea why there is the discovery decal on it? because the bike I have is just blue/silver. Also, the LBS told me that they had 10spd ultegras in stock, but would not fit onto my bike because it was a 9spd. Was he wrong?

Trek sponsored the Discover Channel Bike racing team for a couple of years and the pictured bike was made during that period.

Whether the Ultegra your LBS has will work or not depends on what cage length he has in stock. If he only has the short cage model it won't work as it won't "wrap up" enough chain for your triple crank. As to 9 or 10-speed, I'm almost certain a 10-speed rd will work fine with 9-speed everything else.

Thanks for all the help so far! I've been searching all over eBay and have only found a few long cage ones with decent prices. Am I correct that switching to 105 RD would be a downgrade? I've found a few 105s that have a buy it now option.
https://www.ebay.com/itm/New-Shimano-...4#ht_500wt_715

https://www.ebay.com/itm/New-Shimano-...9#ht_500wt_715

https://www.ebay.com/itm/New-Shimano-...d#ht_500wt_715

These should all fit without a problem? Lastly, if going to 105 is a downgrade, how much of a difference is it? I'm mostly using the bike to commute around campus, and the occasional long ride on the weekends.
Again, thanks for all the suggestions so far.

Unless you are weight watching, going from Ultegra to 105 isn't too much of a downgrade; 105 is normally seen as the sweet spot in the Shimano road range for value / performance, even MY2012 Tiagra (4600) pretty good.

Looking at the ebay links you've given, all look fine, think silver would probably go with your frame better than black.

9 speed shifters, chains, and cassettes can be used with 10 speed derailleurs. Your LBS guy rides the short bus.

If you crashed and damaged the derailler, make sure to get the hanger checked for alignment/bending.

those links show shipping out of Taiwan FWIW. I recently installed a 5600 gs on my daughters 6 speed without issue. Cambria had them on sale for $39 a couple weeks ago, shoulda bought 2.

search for Ultegra GS GS is the designation for long cage. as others mentioned, a 105, tiagra hell even a sora RD would work for you and yes, your lbs guy rides the short bus.

Judging from what LBS people have been telling customers in so many threads I've read, that bus is standing room only.

So I decided to go with the silver 105s as suggested by jimc. I realize they are from Taiwan, but the sellers ratings convince me they're genuine. The hangar was the first thing that was swapped, thanks for the headsup dedhed. I should be back on 2 wheels in a week, can't wait!