AFAIK;
There was no version of 105 between the "Golden Arrow" and the 87 105.

SIS was introduced in 1985-86 with Dura Ace and 600 (coined N600 SIS) N600 was also termed for the post Arabesque 600.
in 1986 or starting the 1987 Bicycle MY the 105 line had with SIS

If i remember right Light Action did not have SIS til 1987 MY.

the 1987 105 or 1050 group was all new as it had Aero Brake levers, SLR, SIS, Biopace and all the other new goodies that Shimano introduced at the time. It shared no common parts from the previous 105 group (Golden Arrow)

Unlike at the time with N600, the SIS and non SIS grouppos shared everything common except Shifters and Rear Derailuer.

The differences are minor but they are there. A 105SC would be slightly lighter due to greater use of aluminum. I believe the major difference was that both cage plates were steel in the RX100, while 105SC had an aluminum outer cage plate.

I know the difference of a year is so minor- It's kind of fun to do the looking and stuff.

My 1986 Trek 400 Elance had 6 speed SIS Light Action. The catalog announced it as "Well matched components include the Shimano S.I.S derailleur shiftyng system, previously found on only the costliest racing machines..."

http://www.vintage-trek.com/images/t...rekCatalog.pdf

Because that catalog had to come out BEFORE the 86 model year- it kind of fudges the availability date of SIS in lower groups- to me at least.

Almost.

SIS was introduced in 1985 on New Dura-Ace, which was a completely new design.

New 600EX, which had debuted in 1984, was upgraded to SIS in 1986 with an optional SIS compatible rear derailleur, levers and freewheel. It also rec'd new brake calipers and levers in 1986, with an aero lever option inherited from 600AX. The "New" prefix was officially dropped in 1986, with the group now being referred to as just 600EX. However it is common practice to still refer to this group as New 600EX, to distinguish it from earlier 600EX.

New 105 was introduced in 1987 and was a completely designed group. It was the first 105 group with SIS.

Light Action first appeared in 1986 and had an optional SIS rear derailleur, shift lever and freewheel that year.

That's very interesting- was 105 still available in 86 in the golden arrow friction iteration?

Also- the ratcheting SL-422 Light Action shifters appear to be a little more common than the indexed S424, but again, I assume the Light Action "group" sat lower than 105, so it's interesting that a new middle/lower group would get SIS, but the middle group stayed friction.

And don't get me wrong- the Light Action stuff looked nice, and it functioned great. IMO- the Z206 front derailleur is a real workhorse- it looks nice and classy, and it handles every range of double and triple without looking overbuilt or overly heavy.

OR...

Is Light Action a sort of sub-group of 105? I seem to recall that (at least some of) the Z series stuff was a part of the 105 golden arrow group. Or were the parts just shared... Or, more than likely, I'm just reading WAY too much into it because I'm a dork like that...

Yes, fist generation (aka Golden Arrow), friction shifting 105 was still available in 1986. But by that time it had gone though some cosmetic changes (see pic).

I've also wondered why they skipped over 105 for SIS in 1986. I suspect that New 105 may actually have been scheduled for the 1986 model year but there was some kind of delay, as Shimano released at least three system catalogues in 1986. The first (January 1986) didn't even mention a 105 group! Then there was an August 1986 catalogue that included New 105. The official 1987 catalogue came out in December 1986 and included Sante, which wasn't in either of the two earlier catalogues. So New 105 was almost a mid-year introduction; earlier than normal but too late for specifying on 1986 models. The fact that there was no 105 group in the January 1986 catalogue may be an indicator that hey had hoped to have the New 105 group ready for it. Also, the 1986 cosmetics foretell New 105, so maybe it was a stopgap measure. I think that Shimano was aware of SunTour trying to rush AccuShift to market for 1987 and wanted to cover as many price points as possible, before them. Of course there is nothing concrete. It's just speculation based on circumstantial evidence but sometimes that's all you have.

I never considered Light Action a sub-group of 105 They were heavier and less expensive than 105. Shimano never developed any other components around them and they were typically found on upper entry level bicycles with mixed components such as Sanshin hubs, SR cranks & Z-series brakes.

Thanks for the clarification.

i should have remembered the N600 Aero levers since i have a 1986 Trek 560 with them (although finding hoods for them are impossible)

As far as light Action, I dont remember seeing them til 1987, but i was a young pup then. But as T-Mar says it was not comparable as 105 but a really good lower option. I had a 1987 Diamond Back that had Light Action SIS and it worked great.

Here's the Light Action portion of the catalogue chart. Note the January 1986 copyright date at the bottom.

Like T-Mar points out, I saw a lot of Light Action on low end bikes when entering Trek 88-85 catalogs into Sprocket. Leads me to believe they were low quality, below Sora/RX100.

Then again, I did install one on my brothers Miyata last year. It shifted well so it was not of dubious quality like some bottom of the barrel Shimano derailleurs.

RX100 was what became Sora, because it existed at the same time as 105 at lower quality.

Keep in mind again about Trek- their entry level stuff wasn't 'entry level' for a lot of other makers.

What I know of indexed Light Action is from my 1986 Trek 400 Elance... one step up from entry level for Trek- it's a great bike all around. 531/CrMo, decent if not spectacular components.


I find it interesting that the L-525 SS is index compatible but the L-525 GS is not.

http://www.bikeforums.net/attachment...p;d=1453136967


After looking at the 1986 Vintage Trek page, I'd never paid attention that the 400T Elance was not SIS, but the 400D was.

Agreed. Initially, I thought that it might be due to the fact that Shimano did not have a SIS compatible freewheel that was larger than 28T, which is what the GS & SGS versions would have been used with. However, Shimano upgraded Deore XT to SIS in 1987 and the RD-L525GS & SGS still weren't listed as SIS compatible. Furthermore, Shimano introduced a new Light Series in 1987, the L532. Again, the SS version was SIS compatible, but the GS & SGS versions weren't! I can only assume that there was some sort of difference in geometry, The upper pivot casting would have a longer drop and/or different angle to accommodate the larger cogs and there may have been some other differences associated with this casting. It certainly would be interesting to try a long cage Light Action rear derailleur with SIS shifters and SIS freewheel.

Regardless, I second the numerous comments that the Light Action series shifted very well. However, they do have an Achilles Heel from a durability perspective. The cut-out in the parallelogram's rear arm to accommodate the pre-select mechanism does create a weak point and I have seen a number with broken rear arms.

Pretty sure I used a 525GS with index shifters when I converted my daughter's Shogun to a triple. I'll check in the morning, as it's bloody cold in the barn tonight.

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