justinzane

I'm wondering about the durability of rear deraillers. My current RD has gotten to be as crooked as the proverbial dogs hind leg and I wondering about what to replace it with. The obvious criteria are chain width and chain wrap that match my cranks and cogs. Lower weight is certainly nice, but I want to find something that is relatively bulletproof. My primary concern is resistance to bumps and bangs when the bike gets blown over by the wind, gets banged by others in a bike rack, etc. Since I'm using friction shifting, index compatibility is not relevant for me, but I'll assume standard Shimano indexing since Campy and some SRAM are really specific to their own shifters.

Are there any product lines well known for their durability? Known to be really fragile? Or is it impossible to make generalizations beyond a particular specific model?

fietsbob

Dont crash or drop the bike onto its right side and you really extend the useful lifespan .

I'm still using the pre indexing stuff I got in the mid 70's..

nfmisso

Shimano RD-TX55 - cheep and durable. Increasing $$$ means lower weight and less durable.

MRT2

I have never had a problem with any Shimano rear derailleur, and I think all my family bikes have some kind of Shimano derailleur. Derailleurs I have owned or used in include Tourney, Acera, STX, Alivio, Deore XT, 2300, and Tiagra. The higher end ones are lighter and shift better. Hence, I would rather have a Deore XT than a Tourney or Acera, but they all work, and are pretty reliable, even over years.

70sSanO

My latest RD weapon is an XTR M900/M910. It seems to have a good balance of performance and durability. It is a medium cage to 32t.

For short cage applications that are friction, (or index), Dura Ace 7402 rear derailleur was my weapon of choice for years. I ran it with a 28t with no issues and even tried a 30t, but neither of us were happy with that combo.

These are about as bullet proof as I have found.

John

Neddog

I had to replace a bent Shimano Tourney, but that was such a rare occasion and on a pre-owned project bike so I really could make no generalizations from it. It was enough to encourage me to keep a spare derailieur though, so now I have this really beautiful and rare Suntour on standby if I ever need it. XD

70sSanO

Now if you want to really go back in time. I have yet to find a Suntour Cyclone derailleur that was abused to where it wouldn't work. Although I'm sure that they are out there.

However, I have seen bikes left out in the rain and half rusted and I could still get the Cyclone stuff to work.

John

79pmooney

I went a couple of decades riding Cyclones with both the short and long cages. When play started developing in either the cage pivot or the parallelogram, I would go to a bike sop, sort through their box of trashed derailleurs, find a new one with a broken other half and rebuild mine. (This was pure luxury. Like you said, those Cyclones shifted very well long after a lot of play developed.)

Ben

Camplex

SunTour in general, yes. I have a bike with a long-cage Cyclone and it seems indestructible. Same with my backup, the XC7000 Sport.

travbikeman

Last time I had to replace a derailleur for failure.........think it was 1986 or 87. The basic store bought Shimano on my old Columbia Blaze died. Replaced it with a nice Suntour at the time. I miss Suntour.

corrado33

Is the derailleur bent or is the hanger bent?

I don't often see derailleurs bent, even on abused bikes. They're all pretty tough. The hangers are supposed to bend before the derailleur. That's the point of them.

davidad

My 105 long cage Der. gave out after 90,000 miles. I have 28k miles on the new Ultegra.

JamesRL

I'd say 90,000 miles is pretty good service.

mtnbke

I just can't help it, this thread begs for a post about Mavic SSC derailleurs.

The old Mavic "erector set" derailleurs (friction) and the 8-speed indexing group that Lemond won a Tour on and that Sean Kelly won a lot of stages on were essentially LIFETIME kit. While the friction 820 shifters were the same price as Record Syncro the 821 7/8 indexing levers were almost twice as much. The Mavic front derailleurs were more than twice the cost of Chorus, and more than $10 more than Record at the time. The Campagnolo Record rear derailleur and the Mavic 840/841/845 were the same price, but half again more than Chorus, both. At the cranksets the Mavic was again about $10 more than Campy Record and about $75 more than Chorus at the time.

The reason Mavic kit was so expensive during the peak Campy era of titanium and non-finicky "too many cogs" drivetrains? Mavic derailleurs and components were completely modular. Mavic derailleurs were put together with cir-clips or e-clips and any damaged piece was completely replaceable with a spare. Making Mavic kit more modular than just being completely modular, the same Mavic rear derailleur 840/841 that won a TdF (Lemond) and lots of stages (Kelly) on the road bike was identical to the Mavic 845 rear derailleur that was in the Mountain bike group. Source a spare long cage and you could convert your short cage (840) or medium cage (841) to a triple/long cage setup to use on your mountain bike our touring bike. The only difference between the Mavic 845 and the road derailleurs was the the mountain bike version had a Sticker while the road versions were silkscreened/engraved (whatever it was). I've actually always wanted to peel off the sticker on my Mavic 845 long cage to see if it says Mavic under there in the understated way the roadie derailleurs are, only I've never had the courage.

Beyond just moving the rear derailleur from bike-to-bike for racing, touring, or mountain biking you could move the front derailleur from a braze-on set-up to different clamps and back again. Again everything was built using cir-clips and every aspect of the derailleur was modular. In fact that's the kool guy trick to buying vintage Mavic derailleurs. It doesn't matter if "that" front derailluer is braze-on or the clamp fits your current build, and it doesn't matter if the rear is the right cage length for your current needs, you can just swap out the bits from your Mavic stash to make everything what you want it to be.

The Mavic kit was world class. Make no mistake. The rear hubs were so stout that they literally were just the same road hubs used on the TdF and gran tour bikes but with a 135mm axle. You could swap back and forth between a 130mm or 135mm axle depending on whether you needed the hubs on your touring/mountain bike or on your road bike. In this era when every freewheel hub was failing left and right due to the axle not being supported only to the bearing at the flange width of the hub (think largest cog), those constant failures propelled in the free hub era where the axle was supported to the bearing at the width of the smallest cog. The exception to the failures were Mavic and Phil Wood hubs. Believe it or not a Mavic hub that won the TdF and lots of gran tour stages also had the same alloy axle diameter as a Phil Wood touring hub at 15mm. The Mavic necks down at the bearings, but the bombproof nature of the axles is what allowed Mavic to get away with using their road race hubs as 135mm Mountain Bike hubs with zero changes save swapping the longer axle and changing the band to green and calling it a Mavic 531.

BikePro.com / Buyer's Guide / Archive Reviews of Mavic Hubs - Bicycle Parts at discount prices / the Buyer's Guide / Bicycle Parts at their finest! / Professional Bicycle Source / Bike Pro

So what happened? Well, the market changed and most people couldn't afford kit that was more expensive than Campagnolo Record and significantly more expensive than Chorus. The average dentist or anesthesiologist doesn't just want good kit, he wants good kit that other people recognize as good kit. Its about the cache. Its why celebrities and athletes buy more Ferraris than Masarattis. They want everyone to know what they have, as much as they want to have something good. Now don't get me wrong, Mavic derailleurs weren't the "best." While the derailleurs used an expensive titanium bolt to attach to the derailleur hanger for some madding reason Mavic used plate steel for the cages instead of alloy. The derailleurs weren't the lightest. That didn't stop Lemond or Kelly, but they just didn't look "fast" compared to some of the Campagnolo stuff. Also the indexing shifting for both the road downtube levers and the mountain bike shifters wasn't the best.

Mavic would perfect the trim from integrated lever with the Mektronic group that actually continued to use the same front Derailluer with a more elegant trim function than even Campagnolo has ever managed. This was Mavic's second electronically shifting derailluer group after Zap, in case anyone is all impressed with their Di2 or EPS setup that shows up essentially 16 to 20 years after Mavic first managed it. The Mavic electronic derailleurs only used electrical current to send the signal, the pedaling action actually powered the shift, which is a more elegant design with less battery problems than a Di2 or EPS system. Most people don't remember that Chris Boardman competed on Mavic Zap/Mektronic his ENTIRE professional career, and even won an Olympic Bronze (to Indurain and Olano) on it. Mektronic was also wireless, which many Mavic enthusiasts actually thought of as a regression believe it or not.

From Inside Peloton: Mavic Zap - Peloton Magazine

Mavic historical pricing compared to Campy:
December 2009 ~ tears for gears

So what is the punchline of all of this? The Mavic front derailleur was bombproof. Good enough for a TdF win in the biggest gran tour of them all and lots of Tour stage wins. That 860/862 front derailleur was good enough for a road bike for the best cyclist in the world, and was the SAME front derailleur that became the Mavic 875 for the mountain bike group. The insanity of Mavic was that while the company tried to innovate first, and do everything with "no second best way" they made strange decisions. They used steel adjusting screws and steel plates for the derailleur. They just as easily could have used titanium or magnesium to lighten up the derailleur considering the price.

The irony of the Mavic derailleurs is that they were touted as the "last front derailleurs you would ever have to buy":
Mavic Front Derailleurs - Bicycle Parts at discount prices / the Buyer's Guide / Bicycle Parts at their finest! / Professional Bicycle Source / Bike Pro

Which was apt considering how elegantly they moved between different clamp sizes with the shim setup, or how easily they could be moved from braze-on to clamp by just undoing the cir-clips and swapping modular bits. However, even though spares were available these lifetime derailleurs now find themselves forgotten on the shelf. All the modular spares bits for these modular components (cages, pivot linkage, cage etc.) while they were available to rebuild these or transform them, Mavic no longer maintains those spares in active production. So while they are still truly lifetime derailleurs for those with spares, they aren't quite the same as they once were where any bit could be sourced from your local LBS off-the-shelf, well great LBS shops anyway.

So when front and rear derailleurs proved themselves as being capable of winning a TdF (when was the last time Campagnolo managed that anyway?) and lots of stage wins, and ALSO proved to be capable of being bombproof enough to be used as a part of a mountain bike group, what else needs to be said.

Light, strong, rebuildable. Probably the best derailleurs ever made. And being 8-speed compatible with a triple/long cage option and completely modular and rebuildable how strange is it that the TdF racing kit is also ideal for non-finikcy shifting perfect for unsupported round the world touring (due to the ability to carry spare bits)? Who ever confuses Phil Wood hubs with Campagnolo Record hubs, as touring options? Nobody. However, Mavic kit was that bombproof, that good. The same stuff good enough for a gran tour, a mountain bike, any bike in your fleet.

The Mavic front derailleurs were essentially unchanged from being introduced in the 70s all the way through the Mountain bike group and the Zap and Mektronic group in 1994. That's staggering. Think about how many iterations and offerings Campagnolo, Shimano, and Suntour wade through during that timeline!

Bulletproof. Functional. Good enough for a MTB, but good enough for the TdF and Lemond/Kelly and Boardman's entire career as well. Modular. If the answer to the OP's question isn't the Mavic 821 front derailleur and the Mavic 840/841/845 derailleur, I don't think the discussion has much integrity.

Now all that being said, nothing is as beautiful, at least to me, as a Mavic "erector set" rear derailleur 801/851 that originally accompanied the release of the 820/821 front in the 70s. No its not a slant-parallelogram design but it might be the most beautiful derailleur ever manufactured. Putting it up against a Nuovo Record derailleur makes the Campagnolo offering look like something cheap from Wal-Mart, retrospectively.

3alarmer 

...you can read reviews and get a general sense of the history of these on Disraeli Gears.

justinzane

Any suggestions as to appropriate sacrifices to the wind god? What about pacification methods for garage gremlins? Both seem to feel that the act of crashing someone's bike is just not worth it if it don't squish the mechs.

justinzane

I'm using SunTour Accushifts, 7 speed indexed, in friction mode and they are built to last through WWIII. I'll keep an eye out from a good deal on a Cyclone, if nothing else as a bulletproob backup.

Are we just old crochety bastards, that we so miss the way everything from bike kit to houses were built in the proverbial good old days? Or have things just gotten disposable in all aspects of life?

justinzane

Neither of the pulleys are coplanar with the cogs or with each other. They will straighten enough to ride, but get bent with nothing more than really hard pedaling in lower gears.

corrado33

That doesn't make sense. There's no torque on the pulleys other than in the plane of the chain. The cogs receive the brunt of your hard pedaling, the derailleur doesn't really care.

Perplexing.

justinzane

Most perplexing!

Now, I'm using friction shifting, so I'll get the RD slightly misaligned which surely interacts with things. But I thought that it was odd as well since the force should be transferred across the TOP run of chain. And, the chain, cogs and chainrings are all close enough to new that wear is not an issue.

The fact that the pulleys are continuously out of plane is indisputable. And, they are not even consistently misaligned, which is worse. I'd try to figure it out, but it just ain't worth it. I'm just trying to get a good training/travelling RD that can handle a clumsy oaf of a rider.

corrado33

You may also want to consider the RD "guards" they put on really cheap bikes. They protect the RD from getting bent in bike racks, when falling over, etc.

Something like this.

Cycling Bike Bicycle Rear Derailleur Chain Stay Guard Gear Aluminum Protector | eBay

alexaschwanden

I saw today a broken Di2 ultegra derailleur with the chain in a knot, broken spokes and the owner pissed.

fietsbob

They are not so dorky discs after all .

RoadGuy

If you lay the bike down with the non-driveside down, it cannot fall over.

If you drop the bike on the driveside, or somebody crunches it while on the bike rack, or you crash on the driveside, you will bend or break parts (derailleur and/or derailleur hanger).

The same people who make fun of riders who choose to install (or leave the spoke protector installed) are the ones who scream the loudest when the frame of their expensive carbon wonder, and the rear wheel get trashed in a derailleur incident. There should be a rule that if you make fun of dork discs, and riders of bikes with dork discs, you are not allowed to complain when you suffer a rear derailleur incident.

DBrown9383

I disagree