KenNC

I am fixing up a 1981 Peugeot 12 speed (Atom 77 compact freewheel), which has a Peugeot labelled Simplex rear derailleur. I have a Suntour V GT-Luxe rear derailleur that I can swap in, or I can leave well-enough alone. Couldn't test out the Simplex before i disassembled. Will be shipping the bike back to a friend when I am finished so won't have much of a chance to change it again later. From what I've read the Suntour is considered a substantial upgrade to the Simplex but wanted to double check here. Will be able to do some test rides, but not much because the bike isn't close to my size. Opinions welcome, and thank you!

The Golden Boy 

I personally would if it were my bike.

Although there's fun in having an "oddball" part, it wouldn't be anywhere near fun if that unique part didn't work as well as the better established one. Suntour stuff works- in a friction environment- it just works well... it's also sufficiently "cool."

revcp 

Suntour is better, but also consider that the GT is the touring rd, meaning it's at least a medium cage, possibly long. Allowing for additional chain wrap is not an issue per se, but it won't be as "quick" as a short cage. For functionality and durability on a daily rider, however, it will be great.

3speedslow

If the Simplex is the prestige model chances are it is already cracked, if it is one of their all metal DR's, it should work fine. Get some feedback from your friend, see if he has any 'druthers. Tell him also that you would rather give him his bike back with full confidence of it's mechanical workings. Job is done when the job is done.

Yes I much prefer Suntour on my bikes and witching out Simplex for Suntour was very common back in the day.

Grand Bois

Only on low end Peugeots that use a claw or later higher end models that have a universal hanger.

auchencrow

+1

And which Simplex? If it was an SX610 or something similar I'd elect to keep it.

Grand Bois

It's the front Prestige derailer that cracks. The rears wear out and the pulleys disintegrate.

I'm a fan of the SX610, but a Suntour would be a big improvement.

auchencrow

All true - but the Suntour wouldn't look quite as right on a higher-end Pug.

rootboy 

I'd keep the Simplex, if it is still in good condition, and works. Agree with Auchencrow.
By 1981, wasn't the Simplex gear pretty good? With fewer plastic parts?

JohnDThompson 

I'm with auchencrow. While the SunTour might perform better than an SX610, it wouldn't be a huge improvement. And if the bike has Simplex shifters, they'll work better with the Simplex derailleur; the smaller barrel on the Simplex shifter needs to wrap a lot of cable when used with a SunTour derailleur.

Grand Bois

Since the bike is for a friend, I think that the Suntour is the better choice because it will be more reliable. an SX610 is not an all-metal derailer. The arms are Delrin hidden under thin metal. It has the same self-destructing pulleys as the cheap Prestige. I personally object to Japanese parts on my French bikes, but it's not my bike and most people don't care. I have SX610s on two bikes now and a few spares in a drawer. Mine have Bullseye pulleys. They shift decently, but they don't have slant parallelograms, so they're not in the same league with Suntour V.

I've used Simplex Retrofriction shifters with a Suntour V GT-Luxe. It did take a lot of shifter movement, but it worked over seven speeds and it felt very precise.

KenNC

I should have mentioned that I have already replaced the Simplex shifters with Suntour retrofriction shifters. And, the original front derailleur was gone and previously replaced with something weird and cheap, don't remember what, and I already replaced the front derailleur with a Suntour. I don't know the exact model f the Simplex rear derailleur, but the bike is a 1981 UO10, which basically looks like a UO8 with alloy rims, crank, and handlebars....

Grand Bois

Suntour didn't make retrofriction shifters. I think you're talking about their excellent Power Shifters.

I think your RD may be an SX410.

Chombi

Simplex RDs like the SX610 is not bad at all, compared to then contemporary Suntour RD's....but do understand that changing the Simplex to something like maybe a Suntour Cyclone MkII, or maybe even the VGT RD's could be irreversible....
I did so on my Peugeot in the 80's, and I ended up never looking back, even if it meant that my bike ended up looking a bit "franken" when one sees the only non-French component on it, "squatting" on the derailleur hanger.... The Suntours were/are just sooo good!

Grand Bois

There's nothing irreversible about changing from one claw hung derailer to another. The bike is a UO10.

avzay66

on my Peugeot PKN-10 I got rid of Simplex drivetrain and installed Suntour Cyclone mk2. Saved a ton of weight and it shifts great.

v-gt luxe is pretty heavy, so I am not sure you will gain much by switching.

JohnDThompson 

You have nothing to lose then, except the cost of the derailleur.

It should be stamped on the derailleur, e.g. "SX 660":

Chombi

I used "irreversable" not to describe a mechanical condition...more to describe a possible permanent change in preference of RDs...
I should have put quotation marks on the word to hint at that.....

John E

I did the same conversion on my PKN-10, in addition to regearing it 48-45-34/13-15-17-19-21-24, which the Cyclone handled just fine. The V-GT is a great wide range derailleur, arguably one of the best of its genre, but I think it is too heavy and not the right geometry for narrow or midrange gearing, such as mine. It did work very well with the original 54-47/14-34 half-step configuration on my Nishiki, and on my wife's UO-8 (now my commuter), which I set up for her as 52-42/16-32 for her.

Grand Bois

Like 75 grams or so is going to make a big difference on an 26 pound (I'm guessing) UO10.

Grand Bois

Now I get it!

Grand Bois

That SX660 is one that I would like to have. It appears to have the same all-metal arms as my SLJ 5500. Note that it has the larger Simplex tag that is normally seen only on the SLJ series. Does it have aluminum pulley bolts as on a SLJ?

Grand Bois

Still, none of the Simplexes has a slant parallelogram, so they won't shift like a Suntour if you use a freewheel with a reasonable 28t cog.

Chombi

The little bit of weight savings was just icing on the cake. All of us that owned a Cyclone MkII knows that It's really the super precise and smooth shifting of the RD is what is was more about. When I could not ride my bike on rainy days back then, I would flip my bike on its saddle and handlebar in my college apartment living room and run the RD through the gears repeatedly just to hear and feel it shift so slickly and precisely, especially as combined with my Simplex retrofriction shifters! It also helped a lot that it looked really sleek and modern compared to other derailleurs of its class back then.
Crap! I just realized that we might have just raised the prices of MkIIs at eBay another 20 bucks!

photogravity

+1 Keep what's there. But if you are really looking to make some changed, an IGH would be the most appropriate direction IMO.