timsuren said:
I have an entry level trek and the rear derailleur was damaged beyond repair in a recent cross-country move. It is outfitted with Shimano Tiagra group components, but thought it an opportunity to upgrade the derailleur now. Any suggestions on what to upgrade to? Dura-ace? Ultegra? 105s? Also, with changing out this, is there any other components that I should swap out as well? The bike has about 2000 miles on it. working on a budget of <$300.
How damaged is the rear derailleur?
Are you sure it wasn't the derailleur hanger which was bent?
FWIW. My observation is that most of the less expensive Shimano rear derailleurs are as good as the more expensive ones ... there are exceptions, but if a Shimano rear derailleur has the same silhouette, then it will perform the same if properly adjusted & maintained (lubed) ...
The difference between a vintage 200GS which I have and my
normal rise, XTR rear derailleurs is mostly in the weight & finish AND the bearings (or, lack of) in the pulley wheels -- the 200GS probably weighs about 2x as much as the XTR rear derailleur because the 200GS is mostly steel & the XTR is mostly alloy ...
The Ultegra & Dura Ace rear derailleurs have bearings & the pulley wheels whereas Shimano's lesser rear derailleurs (e.g., 105, Tiagra, etc.) use bushings which need to be oiled/greased on-day-one since it seems that Shimano doesn't bother to ...
Because the cost differential between a 105 & an Ultegra is minimal, most pre-6700, Ultegra components are a best-buy for almost everyone because it is hard to find the stuff below 105 at a bike shop. Letting mail order OR eBay be your friend will allow you to find/buy the components below the 105 line.
Presuming you are using 9-speed shifters, I would suggest that you consider getting an SLX or XT rear derailleur because it will give you greater options with regard to cassettes ... i.e., you can use a cassette with a wider gearing range with less effort.
The Shimano 950/952 [the primary difference between the two is the number of teeth on the pulley wheels] XTR rear derailleur has generally been my preferred rear derailleur on my
road bikes.
The
caveat to choosing most Shimano MTB rear derailleurs is that many are now "Rapid Rise" (reverse movement/pull) ... some of Shimano's MTB rear derailleurs (like the SLX) only seem to be available as Rapid Rise, now ...
Rapid Rise should actually be a 'plus' with Shimano ROAD shifters when shifting under load (i.e., going uphill) because it seems to be a benefit on MTBs ...
While I prefer [and, recommend] Campagnolo shifters, I've mounted a Rapid Rise XT rear derailleur on one of my road frames which I will eventually mate with a pair of Shimano shifters if I ever get motivated enough to complete the build (I need to put a chain on the bike + wrap the handlebars); and then, I'll do a road test to confirm the superiority of the Rapid Rise rear derailleur with the Shimano road shifters to using a 'normal' rear derailleur ... MANY people claim they don't have a problem shifting to a larger cog with their Shimano shifters when their drivetrain is under load; so, if you haven't experienced balky shifting then don't even bother to consider a Rapid Rise rear derailleur.
Anyway, THAT's a long-and-convoluted way of saying that you should let your budget-OR-ego be your guide in choosing a replacement rear derailleur.