drabina

I have 2009 Fuji Crosstown 4.0 bike and would like to upgrade rear derailleur. Currently, I have Sunrace RDM4S which I am not happy with (performance, plastic parts, etc). I have posted my question in the hybrid forum but was redirected here. I only put about 250 miles a year on the bike and all my riding is purely recreational on flat paved roads. I do not need more than 7-speeds so I would like to stay with rear-only derailleur system.

Would Shimano Tourney or Acera be a good replacement for the Sunrace? If not, anything else that's 7-speed compatible? The shifters I have are: SRAM MRX Grip shift 7-speed. I am looking for something that's basically plug and play. I will be changing brakes and wheels also but would like to keep shifters and freewheel if possible.

Here are the full specs of the bike:
2009 Fuji Crosstown

Thanks.

CACycling

Tourney would not be an upgrade. I'd go with Deore which can usually be had for little more than Acera or Alivio. Why are you changing wheels and brakes? With the small amount of miles you've ridden, neither should be needing replacement. You'll see a lot more difference by upgrading the tires and brake pads than wheelset and brakes.

JiveTurkey

Either of those would work. Any Shimano MTB RD would work--except the 10-speed only ones (Dyna-Sys). If you wanted more of an upgrade, an 8-speed model like Alivio or 9-speed model like Deore would work as well.

As long as the number of speeds of the rear shifter, cassette/freewheel, and chain match, it doesn't matter what speed the RD is (with the above exception).

The RD also has to be able to handle the largest cog (MTB RDs can handle up to 34T) and chain wrap (with just one chainring, you can use either GS or SGS length cage).

zukahn1 

Either of those should work no problem if you get a 7 speed with the same gearing you have right now you won't need to change anything.

oldskoolwrench

Hard to tell from the photo, but if the frame has an integral derailleur hanger then the Acera would work just fine. If it doesn't then the Tourney would work as well.

In fact, any older 7 speed Shimano rear derailleur will work, as long as it's in good condition, it's a long cage, and you have the frame mounted hanger. Alivio, STX, Exage 300-500LX, RSX... all of these will work.

Alan

drabina

Thanks for replies. So if I understand correctly, with the 7-gear freewheel I have, the Shimano Deore SGS RD-M592 (https://www.amazon.com/Shimano-Deore-.../dp/B002PTQFXA) would work, correct? Sorry if that's a simple question but while I am handy with wrench, all the tech talk about chain wrap, long cages, etc is beyond my knowledge.

As to the CACycling's question, I am not upgrading due to wear but because the components that came with the bike are very cheap and of poor quality. The wheels i.e. are too flexible and I need to true them frequently. I am not even sure if they are what the specifications claim to be. There are no labels or markings on the wheel. The rear derailleur is built from plastic parts. Brake levers have the rubber coating separating in few places.

CACycling

That RD will be fine. By the time you replace the RD, wheelset and brakes, you will most likely have spent more on parts than the bike cost new. And you will still have a low-end, freewheel-equipped bike. Might want to consider putting that money toward getting a better bike.

oldskoolwrench

drabina,

Personally, I wouldn't put that kind of money into that Deore rear derailleur; it's overkill for the bike that you have.

A less expensive derailleur will work just as well, especially if you entertain the notion of replacing the bicycle soon.

Alan

Chris Chicago

look for a used one on ebay and save yourself 20 or 30 bucks

gyozadude

I've installed the TX-31/35 RD on a number of bikes as RD replacements and it has very wide range support. It's a bit heavier, but shifts extremely well and comes in models with and w/o additional derailleur bracket. I've only used the direct-bolt-on model, and at $10-$12 for an RD, it's hard to beat. The next level up might be Acera but I think it's no more aesthetically good looking than the TX31 and roughly the same price as Altus M310 RD. Both Acera and Altus are in the $18-$25 range with the Altus maybe a buck or two more. Both shift great; IMO, the Altus looks better with the more modern body shape and beefy-looking dual 13t pulleys. TX and Altus both work with 7/8 speed transmissions and I'm using SRAM MRX grip shifts in 7 speed w/ Altus on my wife's bike right now. I have a commuter with Altus RD riding 8-speeds but in friction mode. For an RD that cheap, it sure shifts great and seems to have no issues with my wet and dry commute but I split my commute up over 3 different bikes. I haven't crashed it yet and don't intend to (knock on wood). But I'm quite pleased with the price-performance of both the TX and Altus RDs.

Retro Grouch 

BINGO!

How does your derailleur attach to the frame? If your frame has an arm that extends downward from the dropout to the derailleur, I'd go with the Acera. If your derailleur contains a kind of "claw" that attaches to the rear axle, you're going to need a Tourney.

quimming

I don't get this. I'm going through a similar debate and I don't know the answer. If it has a claw, isn't it where the built-in derailleur would mount? Can't the OP use the Acera with a claw? If not, then are there claw specific derailleurs and if so which ones?

drabina

Here are the pictures of the derailleur mount:

picture 1
picture 2

Hope that helps since I have no idea what type of mount this is.

Thanks.

Retro Grouch 

That's not a claw. That's a replaceable derailleur hanger. If it was my bike, I'd get the Acera.

drabina

So the Acera will mount without any modifications to the existing mount?

JiveTurkey

Yes. The RD bolts into the silver hanger. The hanger is integral to the frame. The hanger is meant to bend/break--rather than your aluminum frame--if the RD gets banged up and can be replaced.

When replacing the RD, you'll need to either break apart the chain so you can un-thread it from the old RD and through the new RD or remove the pulley bolts and dismantle the cage of the RDs and re-install. The former is the normal way, but you'll probably need a quick-link for the chain since the pins of newer chain cannot be re-installed after driving out.