TheFool

Hi, I'm really new to bikes (so my general understanding, and terminology, is probably off a bit), but want to see if I can get an old bike fixed up that I got for a song at a yard sale. It's a Motorbécane Mirage.

The first thing I've done s far is replace the cable for the rear derailleur, the old cable was broken. It's a Simplex derailleur. I found a few old posts in this forum, most say "get a new derailleur" Maybe I'll end up doing that but my goal in this project is to learn by some experience and frustration about bike repair and maintainence. I.e. i'd rather spend time than money in this case.

After putting on the new cable, the pulleys on the derailleur were too close to the sprocket, i.e. it was dragging on it in the lowest gear. After searching in vain for the nonexistant B screw adjustment, I studied it more closely and tried twisting the larger nut that's behind the derailleur (thin, between the pulleys and the derailleur body), which fixed the angle. But now there's poor tension on the chain and the chain slips. Maybe I screwed it up, or loosened the other end (where it attaches the hanger).

Anyway, my question is, anyone know what the correct way to adjust the angle is? Are there any resources out there for this bike/these parts, or French parts in general, maybe a site that has some of the manuals/instructions?

Thanks!

Retro Grouch 

How many teeth on your biggest rear cog?

As I remember, that Simplex derailleur was designed for no more than 28 teeth. If you have a freewneel with a 34 tooth big cog, as was common in those days, it probably isn't going to work.

The big issue with those Simplex derailleurs was the plastic derailleur body. As a general rule they'd only last a couple of years before the plastic would wear at the pivots and they'd get all sloppy. I'm kind of surpsised to hear of one lasting this long. The common period replacement was a Suntour VGT. It'll handle a 34 tooth big cog too.

San Rensho 

Simplex der repair sequence- Loosen large bolt holding der to dropout, dip derailleur once in trash can, replace derailleur

In addition to Retro Grouch's excellent advice, I believe that Simplex ders just didn't work very well, even when new, because they were not true parralelogram derailluers. If you had a straight block FW (one tooth difference between cogs) you could get them to work, but otherwise, they were sketchy.

Grand Bois

Assuming that your derailer is not damaged or worn out, it should work perfectly well. The only adjustments are to the high and low limit screws. The condition you describe sounds like the derailer is not mounted correctly on the hanger. You're not getting any spring tension.

The common period upgrade was the Suntour VGT, but the common period replacement was another Simplex. They were very inexpensive and meant to be discarded and replaced when they wore out. You can still find new ones for $5-$10.

This may help you. Ignore the indexing part.
https://www.sheldonbrown.com/derailer-adjustment.html

top506

Confirm on both counts.
I replaced the Simplex RD that came on my Atala sometime during the Watergate hearings.
Top

trhouse

Sorry to revive this old thread but in playing around with a Simplex Prestige, Simplex Criterium, and Simplex SX100, I think I have the answer.

The top of these derailleurs have a bolt which which controls the tension of a spring shown at "A" in the photo. This bolt takes a 5 mm Allen wrench. The backside at "B" has a special nut that takes a 14 mm box wrench to loosen. Loosen the nut at "B", then use the Allen wrench at "A" to adjust the spring tension which pulls the pulleys away from the cogs. When the tension is correct, tighten the nut. Not the same as a "B" adjustment screw and requires some dexterity to hold the Allen wrench at the right spot while tightening the nut but it does work.

If rotating the Allen wrench does not feel like tension can be increased, there is a chance that the spring behind the bolt is broken. That was the case with this unit. The bolt and spring are shown in the third photo. The spring tip on the right should come out at 90 degrees to the spring body and engage a hole(s) in the back of the plastic body. This spring has about a 45 tip which in another thread, I did not realize was broken. The broken spring scratched out the bottom of the Delrin body of the derailleur as shown in the fourth photo.

suhinaffy

how is the derailuer meant to sit on the bike ? this is how i have it but think it looks odd[IMG][/IMG]

revolator

Agreed.

The body of the derailleur in that gear should be ~ 4 o'clock position, the picture shows at ~7 o'clock.

suhinaffy

how do i adjust it to the 4 oclock position ?

trhouse

The procedure is described in my last post, but before you do that, I would suggest you read this article by the late Sheldon Brown. The 4 o' clock position is approximate. This article explains how and why this angle is about 4 o' clock. The actual angle will depend on the size of your largest rear sprocket.

https://www.sheldonbrown.com/derailer-adjustment.html

spacemanz

Later that same century.... I finally got the broken jockey pulley changed on my Criterium, & gave everything a good cleaning & lube. It looks just about like new now, other than that foilcal thingy, that says Simplex, being slightly mutilated (I got it that way, honest). Not having a 14mm box wrench, I just used my secret weapon needle-nosed vice-grips.

sliderule2

Better late than never, I guess. I got these Simplex "Prestige" manual images at www.retropeugeot.com.

curbtender

Thanks, just what I was looking for. Pulley was dragging on the freewheel and the tightening of the spring, along with straightening other bits saved a Suntour GT for another project.

WizardOfBoz

Thread started 12 years ago, last (zombie) post 5 years ago.

FWIW, back in the day I set up new bikes that had these RDs. They were c**p then. Get a different derailleur.

Capt. Kirk

I'm way late to the game on this thread. Restoring a UO18C now and rebuilt the simplex rear derailleur. I didn't know about "pretensioning" the springs but figured it out. It was a battle but I think I've got it all sorted now.

Is there anything I should know about the front derailleur installation? I rebuilt the FD also. BTW, I also did not realise that the shifter cables have smaller heads.. Had to buy campagnolo cables to replace the old ones.

yesterbik

very good information.
A lot of thing to learn for newbie.

SJX426 

For some c**p is good enough.

Capt. Kirk

Thanks for the replies. When I restore, i try to use as many original parts as possible, good or bad. I try to avoid resto-mod if I can. This restoration even has the "death stem". I will be riding this bike sparingly (and gently) for casual neighborhood rides.

3alarmer 

.
...for the historical record, and in case anyone reads this thread and is puzzled by it, that whole thing about the top pivot spring being held together by a nut and bolt, so you can adjust the spring tension only works on the models with a built in hanger (the infamous "claw"). On the models designed for installation on a standard Simples dropout, with no stops for the derailleur positioning, the thing mounts with a bolt from the rear. Spring tension is set at the factory, with a crimped on washer with stops that meet the Simples dropout, to position the derailleur correctly.

Once you damage that crimped joint, or remove the washer, it's a very difficult repair to reinstall it, because it was crimped on there in the first place. (part #2978 in the diagram for model 637 NI)

My advice would be not to try this trick with the Prestige derailleurs that do not have that claw hanger. Those are the ones that came on the higher end French bikes.

curbtender

I'm not a purist, but I find myself trying to make things work as sold. If you are not sure what you have, it's best to search the part.

https://velobase.com/

Capt. Kirk

This is the first Peugeot that I've worked on and they are different. The bike being a '73 or '74 made it a bit more challenging but I've learned a lot and lucked out with finding some donor parts. It's coming along nicely. Thanks for advice.

xiaoman1 

Old thread but many have ruined their Simplex deraileurs by doing what seem logical, by trying to remove it by backing out the top hex bolt...so for reference please see the image and read the article.
https://peugeotcoursepb12.wordpress....-installation/

Been there done that, no fun!

Best, Ben

Capt. Kirk

Thanks everyone. I installed the cables today and it shifted through the gears okay. There's a weird skip which I have to figure out but so far so good. I found out the hard way that you should not overtighten the simplex front derailleurs mounting bracket. I cracked and broke the delrin part but luckily I have a replacement.