Simplex shifter: Fixing a spring I didn't know existed

[Xavier Alexandre]

After the success of my crank replacement thanks to your help (SUN xcd and TA 5 vis crank differences), I did a short test ride. Everything was fine crank wise, but I had a rear-shifting issue. The lever would not stay in place with too much tension applied. I initially thought that tightening the screw would be enough but unfortunately the screw was bent. Looking for the ideal replacement screw (The previous one was the first random one I found) I stumbled upon some information on simplex shifter:

The levers have a balancing spring to reduce the likelihood of the lever slipping and as a result can be set up with less tension which makes them smoother in operation.

http://www.classiclightweights.co.uk/components/simplex-retrofriction-components.html

And then I realise that I never had such a smooth operation on my rear derailleur. I always had to tighten it a lot for the lever to stay in place. Fast forward a few turns and here it's, the broken spring. I have ridden with this broken spring since I purchased my bike from the previous owner. I will try to bend a bit of the remaining spring as per https://www.bikeforums.net/classic-vintage/1048156-simplex-retrofrictiton-shifter-broken-spring-repair.html. And try to find another suitable screw.

[Leif Eckstrom]

Thanks for posting this. I might have to do a similar spring fix.
One other tip to pass along from a frequent poster on ibob and classic rendezvous lists (please see his Flickr account under “stronglight” handle for visuals): he suggests using m5 x 0.8 stainless steel bolts with button head allen fitting in 20 mm length as a replacement for the original simplex bolts. You can polish the heads of the bolts for bonus points.
Best,
Leif in Chicago

[David Cummings]

I have a Simplex bar end with a similar broken spring. Of course it’s a different size than the DT version. I don’t know how to bend spring steel or whatever is used in Amy hose springs.

David “Lost the Spring in my Step” in MT

[Scott D]

Yes, I replaced original rusty screws with  stainless  m5 x.8 button cap Allen bolts on my clamp-ons.   Once adjusted,  I never had to to touch them again.  And they look better than the original slotted screws! IMHO.

Scott Davis, Mpls. MiN

[Xavier Alexandre]

Yes, I did source a few suitable screws to replace the worn one. Looking forward to easier to service screws!

Question: Do any of you understand how the Simplex spring work? The bottom extremity fit into the lever slot. But how is the top extremity affixed to the frame? It needs to for the spring to be torsioned when the lever is rotated.

On https://www.bikeforums.net/classic-vintage/1048156-simplex-retrofrictiton-shifter-broken-spring-repair.html I read:

As an aside, I noticed the end of the coil spring without the straightened end (the outer end) is cut at an angle and flares out ever so slightly so that it cuts into the soft inside of the lever body. The lever had a tiny little divot on the inside of the lever body where the old contact point was. It's not really obvious when you are looking at the spring, but I could feel the sharp edge with my finger. I suspect this, in addition to the tight fitting of the bushing, is what holds the tension of the spring.

I do not understand it as I would expect the outer end to be somehow fixed relative to the frame, not the lever. And I do not see any divot on my pieces. The 3670 outer washer could play this role as it is keyed but it is flat and is separated from the spring by the 3668 washer anyway.

I have no clue.

 

[Mark Bulgier]

Xavier Alexandre wrote:

> Question: Do any of you understand how the Simplex spring work? 

Your problem is you are thinking of it as a spring. It is, in a way, but nothing like the normal way we think of springs.  I think it is more useful to think of this as a clutch, rather than as a spring.

One of your sources had this line :

> The levers have a balancing spring to reduce the likelihood of the lever slipping

This is not correct.  The spring-like object in a Simplex does not balance the derailleur spring in any direct way.  It only changes the friction, that tends to prevent rotation, to be larger in one direction than in the other.  Thus retrofriction is the correct term for the Simplex, and the similar Campy "Doppler" shifters..

I insist upon that distinction because there were shifters with an actual balancing spring, such as the old (1970s) Shimano Fingertip (bar-end) shifters.  These had a spring that resisted or balanced the derailleur spring.  In theory, if the shifter spring force matched the der. spring exactly, then you wouldn't need any friction at all.  In practice, you need some, but very little.  Those old Fingertip shifters could be adjusted to have a very light touch in either direction, almost frictionless.

The way you can tell the difference is, note how the Shimano fingertip spring has anchors on both ends.  One end anchors to the shift lever and the other anchors to the shifter "perch" in the handlebar.  Compare to the Simplex clutch, which anchors at one end only -- call that the head.  The "tail" of the spring-like object just drags against the inner hub, which is stationary, anchored to the frame.  The way the tail drags against that hub causes the spiral to open, and thus loosen its grip on the hub when shifted in the direction where you're fighting the der. spring.  When you're shifting in the direction that's assisted by the der. spring, the spiral tightens onto the hub, giving more friction. 

So a Simplex Retrofriction is really more like a Suntour Power Ratchet.  The Suntour was another way to achieve differential friction, more in one direction than the other.  Of the two, I prefer Simplex when new, because it's smoother (no ratchet clicks).  But after the clutch inevitably breaks in the Simplex (as they all do eventually), the Suntour will still be going strong for many more years.

The Shimano Fingertip shifters with the true balancing spring are also super durable.  I have a couple of circa-1972 Fingertip shifters that are still going strong, may never wear out in my lifetime.

BTW the Shimano didn't get as much love as it should have, because most mechanics didn't bother to learn how to adjust them.  You have to overtighten the friction adjuster temporarily while assembling it.  But then after the cable is anchored to the derailleur, you should loosen the friction, down to almost zero.  That last step was often not done, so the shifters went out overtightened, and the user never got to enjoy the main benefit of the design. 

Here are some blog entries you might find interesting:

http://bikeretrogrouch.blogspot.com/2013/09/retro-friction-part-one.html

http://bikeretrogrouch.blogspot.com/2013/09/retro-friction-part-two-copies-and.html

Mark Bulgier

Seattle

[Xavier Alexandre]

Thank you so much for those insights. Happy to see I was not totally crazy to not understand the spring mechanism. I like the idea of the clutch. When I was younger I used to sail a bit and did encounter a similar idea. You could use the outer sleeve of a rope as a kind of 2 way mechanism. When you try to slide a rope cover on a rope by pushing it it would glide. But when pulling the cover would tend to get narrower and constrict the rope. You could do a few interesting contraptions based on this principle. Nowadays you can even buy clutches based on this principle: https://www.youtube.com/watch?v=TEGiqlYzIEw

I love the idea of the Shimano Fingertip too, thanks for bringing them under the light.

I did manage to re-bend the tail of my broken spring as per https://www.bikeforums.net/classic-vintage/1048156-simplex-retrofrictiton-shifter-broken-spring-repair.html. Unfortunately despite having been able to get the shape approximately right it dit not work in my case. Not only I do not get any Retrofriction effect but I'm not even able to get enough normal friction. I guess that friction need to be transmitted through the spring tail and that it now seats to deep below the hub. But maybe I'm missing something since the aforementioned fix from Bike Forums seems to be working for its author. Maybe a washer underneath the spring could help restore the proper height of the spring?

I will try to source either a new spring (Apparently http://www.veloclassique.com has some), replacement levers to get some springs or maybe try this washer idea. I'm not clear yet if I can get other levers to work as the part close to the frame seems to be brazed on the frame and specific to Simplex?

On the left, the unbroken spring from the left lever. On the right, the re-bend broken spring and the broken piece.

[Eli Naeher]

On Sun, Dec 9, 2018, at 6:32 AM, Xavier Alexandre wrote:

I will try to source either a new spring (Apparently http://www.veloclassique.com has some), replacement levers to get some springs or maybe try this washer idea.

Did you have any luck finding a replacement? I'm looking for the same part myself.

Thanks,

Eli

New York

[Michael Arciero]

Nice description and overview of related shifters by Mark. 

I didnt know the Simplex were prone to spring breakage, but not surprised to hear it.  I had two break on me, both rd. 

The fd Simplex shifter worked fine up until I sold the bike. I have multiple sets, but of course, the springs are not reversible so cant use an fd spring from one of the other sets.

[Xavier Alexandre]

I ended up buying new levers entirely in order to get springs. I bought mine on Le bon coin (French Craiglist) but I also found plenty of them on eBay.