CNRed

I'm rebuilding a couple Electra Townies. Both have been abused and well used in the past to the point of replacing several components on both bikes. I'd like to replace the rear 7 speed derailleurs on both. That being said, I would like to replace them with something maybe a little better then what they originally came with.
I've been shopping on Ebay, but there are alot of derailleurs to choose from over alot of diffrent price points. I'd like to keep the cost in the vicinity of less then $50.00 each for a good quality derailleur if that is possible.

alcjphil

You have to first determine which ones will work with your shifter

Iride01 

Why not just get a brand new DR for 11.99 plus shipping? SHIMANO TOURNEY RD-TY 500 REAR DERAILLEUR

Though without knowing the shifters and rear DR you have now, I don't know that this is appropriate for what you want.

eBay has been overpriced for bike parts for well over 15 years. I buy and sell on eBay, but there are many things that are just overpriced because eBay attracts people willing to part with their money because they won't look elsewhere for the best price..

CNRed

The bike I'm presently working on has a Shimano thumb and trigger 7 speed shifter. The bike is a Townie 7D so there is no front delailleur to worry about. There is no derailleur on the bike presently so it's a "clean sheet of paper" so to speak.
I don't mind spending a few extra dollars for a quality derailleur, the problem is I don't know a good one from a bad one, and I don't want to b uy junk.

Iride01 

In the 7 speed DR market, you aren't going to find much new technological innovation that you have in the 11 and 12 speed markets. 7 speed was pretty fleshed out by the 90's.

I'm not entirely sure what "quality" means. Just buy what was probably on it originally. If you can find the exact model and series number on the shifter, then get the Shimano DR that is made to go with it.

There might be other higher tier Shimano DR's that will work fine. However finding the exact model and series number of the shifter will allow you to go to Shimano's compatibility tables and find out what works. I don't know where Shimano puts that number on those type shifters. On STI's, I'd just pull up the rubber hood and see on the body.

I think Tourney is probably Shimano's lowest tier price level. But that doesn't mean it's not a good enough for the job DR. Nor are you really likely to get that much more "Quality" by spending more money.

dedhed

Differences between Shimano Tourney, Altus, Acera, and Alivio components

CNRed

Iride01,
Thanks for the information I'm a "Newbe" at this bicycle stuff, I've built a bunch of motorcycles but this is my first venture into bicycles, they are quite diffrent.
I really don't want to throw money at this, but was attempting to up grade the shifing performance of the bike.
I'll find the Shifter model and see what corresponds with that.
Again, Thanks

CNRed

Thanks, very helpful

Retro Grouch 

It's still not quite a clean sheet. Is there a derailleur mounting finger attached to your frame or does the derailleur attach to a "claw" on the rear axle (my bet)"?

dedhed

Shows it has a replaceable hanger.

https://electra.trekbikes.com/us/en_...Code=greendark

CNRed

It has a hanger, I just replacd it last week.

dedhed

Virtually any Shimano road 6-10 speed or mountain 6-9 speed rear derailleur is compatible with your shifters.
While 9 speed and up run a narrower chain and "sometimes" the RD cage doesn't like a wider 6/7/8 speed chain I've never found it to be an issue - yet.

Microshift also makes budget Shimano compatible derailleurs.

The problem at the moment is finding things "In Stock"

CliffordK

Does it have a front derailleur? What is the rear cassette/freewheel size? What brand/model of derailleurs/shifters are currently on te bikes?

If I was doing an "Upgrade", to Shimano it would probably be either Ultegra 6500/6600/6700.

Or, perhaps a Deore M750 or M760.

Or, Deore XT RD-M772 Shadow.

https://en.wikipedia.org/wiki/Shimano_Deore_XT

Different if trying to stick with SRAM compatible.
https://en.wikibooks.org/wiki/Bicycl...ing_Dimensions

ARider2

The bottom level of the Shimano line is Tourney. The next level up is the Altus and then the Alivio. The Altus and Alivio should work even if your largest cog is a 34 tooth. On the Tourney line some only have 28 tooth capacity and others have a 34 tooth capacity so you'll have to determine how many teeth are on your largest cog. I would go with an Altus as it will do the job quite well.

oldbobcat

It's a Townie, for cryin' out loud. The demands on its rear derailleur are slight. Don't overthink this.

tyrion

Parts are expensive right now because there's a shortage due to the Covid bike boom. I'd make do with what you currently have until prices come down (assuming they will), then take your time and look for bargains.

slightly off topic: anyone predicting a used bike glut when masses of Covid bike newbies decide bicycling isn't their thing?

CNRed

You're right, "It's a Townie". But in Phoenix AZ, they're selling like wild fire.

CNRed

[QUOTE=tyrion;22089670 slightly off topic: anyone predicting a used bike glut when masses of Covid bike newbies decide bicycling isn't their thing?[/QUOTE]

I believe you're right on, new bikes are getting pretty expensive, there are alot of pretty nice used bikes already showing up.
Summertime in Phx is not the best place for Bikes, the heat makes riders get up pretty early in the morning, People new to this sport, in most cases would rather sleep in, the bike will go unused for several months then become a Craigslist ad.
Others will find other less demanding things to do now that the Pandemic has somewhat subsided.

CNRed

Thanks for the tip, bith these bikes have 34 tooth rear sprockets.
I realigned the rear derailleur hanger on the bike I am presently working on, and changed the derailleur with the other bike, It shifts better but still not as crisp as I would like it. It seems to shift from the smallest rear sprocket to the largest just fine, shifting fro large to small is not great.

alcjphil

Poor shifting from a larger to a smaller cog is a classic sign of excessive cable friction. If the cable and housing are old it may be time to replace them

CNRed

Thanks, all the cables and housings are new. I'll take a look at the rear cable loop from the rear frame going into the derailleur itself, maybe I have it in too tight of a loop.

CliffordK

Modern derailleur housing uses a lined non-compressible housing + liner. Wires run longitudinally, not in a spiral.

Couple that with a stainless steel cable, and it works very well.

A cheaper bike could use unlined spiral wound housing and galvanized wires.

hokiefyd 

About the best derailleur you'll find for that bike without having to make any other change is the RD-M591. This was the last pre-Shadow Deore derailleur and is widely regarded as a very nice unit. They're readily available on eBay, though often not inexpensively.

Other good options I can recommend from personal experience...all Shimano, just for ease of reference, and in descending order of price and perceived quality:

RD-T4000: non-Shadow Alivio. It's mostly metal with a very long cage. The front knuckle is plastic, but it's pretty stout.
RD-M360: Acera with 13-tooth pulley wheels. I've had a few of these and I think they're pretty nice for the price. They run quietly and smoothly. As with the T4000, it's a mix of alloy and plastic...the front knuckle is plastic, but all else is metal.
RD-M310: Altus with a 13-tooth upper wheel and 15-tooth lower wheel. This a pretty compact derailleur because of the large wheels (the cage is short).
RD-TX800: current "nicer" Tourney. I don't have personal experience with this one, but it looks very similar to the RD-M360 Acera noted above.

You should able to find some of these at reasonable prices. Especially all but the T4000 (that one may be pricey, like the Deore).

SoSmellyAir

For what this is worth, the current Electra Townies come with an Acera (RD-M360) rear derailleur; I ordered one from REI for my wife last summer but cancelled the order when a similar bike (Electra Loft 7D) became available.

Pop N Wood

I will second that. Currently running an XTR rear derailleur with a shimano 8 speed trigger shifter.