This should be obvious, but no matter how much searching I did, I couldn't come up with a solid source.

1. The common thought is that Simplex pulleys are crap. I have three Simplex DR's and all but one have cracked pulley. The one that is whole exploded today as I was attempting to adjust the derailleurs.
2. Simplex uses the same pulleys as Suntour, 6mm hole. However, those are just as hard to find. The ones you find are expensive, and the condition is questionable.
3. You would THINK that someone like VO would provide a replacement, but it doesn't appear that they do. When I emailed them, they replied with "these may work". https://store.velo-orange.com/index.p...ey-wheels.html Well, the sign on the photo clearly says Shimano, SRAM and Campy - all of which use a 5mm hole.

So, what's a guy with three busted Simplex DR's to do? Anyone have a reasonable solution?

Specifically, I am looking for this guy - I believe it's the Prestige model.



Thanks in advance.

You might just as well buy another new or good condition used Delrin Simplex RD to replace the one on the bike or use as a parts component.... that you can harvest replacement jockey wheels from....
They come up often and cheap enough at eBay anyway.....
Also note that its not just Simplex RDs that have jockey wheels that crack. Early Campy NR/SR RDs from the same time period have jockey wheels that don't seem to fail to crack after some years of use...

And then there is this guy: https://harriscyclery.net/product/sim...illeu-2416.htm

I guess that is what I am wondering - with so many people with Simplex DR's what do they do?! Surely they don't replace their DR's each time a pulley breaks?

Well if your determined to keep using the old Simplex. Your best bet is to find a used Suntour with good pulleys cheap and strip the pulleys. Suntour used the same pulleys on pretty much all of there DR's so a cheap one like a HERO is fine and they are compatiable with Simplex. You can pic one up for about $10 on Ebay, or likely cheaper at a freindly bike coop or LBS.

No in most cases people just replace the whole DR with something better.

I think most of them just go ahead and replace the Delrin Simplex's on their bikes with better/later model ones..... I guess what I'm saying is, when the old plastic RD on your bike asplodes or wears out in some way, it's really a very good excuse to upgrade to an all metal one anyway...cause next time it might not be just the jockey wheels cracking, but maybe a main pivot body or derailleur arm that could result in a unexpected sudden stop of your drivetrain and worse....
I think I can actually see some lightening/greying on the plastic of the main pivot bodies on your RD in the pics......that is not a good sign....

+1 to zukahn1. I think the used Suntour RD route is the best option. Rob the pulleys and put them on your Simplex unit, or just mount a Suntour RD since they are superior. I disagree that Suntour pulleys are expensive and hard to find.

Just a few examples of recently sold items:

$6.30 shipped (includes derailleur)

$8.49 shipped (includes derailleur)

$8.76 (includes derailleur)

$9.99 (includes derailleur)

$9.99 (includes derailleur)

$12.99 (pulleys only)

+1 Suntour Pulleys are not expensive the last set I brought from a actual establsihed LBS that stocks keeps some older parts. I paid $12.00 for a NOS set, I could have gotten a good used set for $8.

I picked up the correct SUntour RD and swapped out the pulleys for a Simplex derailer. It worked great. But not all Suntour rear derailers have the same wheels. The one I used was from the 70's.

Well, it's just not my day. I found a Suntour Vx that's pretty beat up, but with decent shape pulleys in my parts bin. But it appears that the Vx model is not meant to be taken apart! One pulley came out easy (just a bolt). The other appears to be attached to the spring bolt?

The Suntour VX can be a pain to take apart but it can be done fairly eaisly if your scraping it. You need to to undue tha allen bolt on the spring assemble oppesit the the pulley then you can pull the cage completely off, from there just use a set of vice grips to turn the post and you will be able to remove the pulley.

Performance bike has some alloy pulleys with sealed bearing that are 6mm center (at least the bearings are). 10T, around $12 or so.

Campy pullies often crack, but don't fail. The pulley just splits, but no teeth are lost.

The ones I posted about are from a on Ebay, and have the solid color look to them since the shields/hubs cover the entire bearing and are the same color as the pulley.

These are the ones that can be carefully drilled or reamed to 6mm, since the center hubs are aluminum.

They are narrower than Suntour/Simplex so may need a washer under the head of each bolt, and may require narrower chain.

They're coming from Canada I see, and the vendor seems to be a very large machining/anodizing outfit that also sells anodizing chemicals.

I would avoid alloy replacement pulleys they are noisey and don't ever fit work work quit right. You get a nice metal on metal grind sound feel even on the correct ones put on newer Shimano stuff. It is not a mistake that nearly all DR's vintage and new spec hard plastic as original the makers could have speced alloy for basicaly the same price, but chose the hard plastic.

^ My Bullseye alloy pulleys are nice and quiet. Those are the only alloy replacements that I have tried however.

That has been my experience as well, and I have Bullseyes on three bikes. It will be four when I can find some more spacer washers.

Make 'em!
Old school stuff needs old school approach.
I made mine out of wood but you can use aluminium, polycarbonate, or even Tufnol for a real OS solution.
Just work out the PCD (Pitch circle diameter) of the teeth (10), drill with a 8mm.
Drill centre hole and bush with copper tube.
Sandwich between two washers.
Hey Presto!
Job done.
Ask me for a photo.
Nick T

Hi I have some nos simplex pulleys.

Are they off-set asymmetrical?

Wondering if you took a modern one, with the 5mm hole, and drilled it out to 6mm, if that wouldn't work...... There is a fair bit of plastic there, and 5 seconds with a drill press would leave you with a 6mm hole.

I remember the Prestige's pulleys being the same as each other ( IIRC). Couldn't you just use one of the tension pulleys, from one of the three you already have, as a Jocky pulley?

Just saw a pair on Ebay for 20 bucks

Not all bike stores are greated equal. Many are very focused on selling bikes. ONE of my local ones has a GREAT mechanic. He sold me the two Suntour trash assemblies from his stash for $1. Says he has a barrel full of them. I know the gears are partly warn but for a buck versus $20+ worth a try. Parts fit fine on my 1985 Simplex 410SX rear derailleur.

The above is plan 'A'. Get my bike back on the road. Now for plan 'B'. Have seen many people talk about drilling out Shimano 5mm hole pulleys but have not heard anyone say they actually did it. SO..... Amazon is having a sail on they Shimano Upper/Lower 5-8sp 10T pulley set. They are supposedly $20 sets on sale for $3.95 a set. Shipping only increases by about 20 cents if I order two sets. So I ordered two sets for $13.09 and that gives me 4 pulleys. Will see what it takes to modify them for a 6mm hole so that they can fit on my Simplex 410SX. Stay tuned.