nonhunner

Hi all!

I'm looking for some advice on comparability.
Right now I have a Shimano 600 arabesque derailleur, a SRAM 1070 10speed cassette, and friction shifters (also 600 arabesque).

I'm trying to figure out if I can get SRAM apex 2x10 double tap shifters? I've been trying to find the facts sheets online and I can't seem to bring anything up. Maybe I'm not typing in the right words etc...any help obviously really appreciated as I'm looking to upgrade my steel frame with some modern parts.

Kontact

Sure. You'll need a SRAM 10 or 11 road rear derailleur as well. You might not need a different front derailleur.

nonhunner

Sorry if this is a really stupid question but why do you need a new derailleur? When I've taken the (admittedly old style) ones apart it's just springs and movement back and forth. Is there something different about the new ones? This is more just for my personal interest. But right now the derailleur seems like it should be compatible with anything so long as it has the reach!

Kontact

The rear derailleur translates an amount of cable pull into an amount of lateral shift movement. That is called the actuation ratio. Your 600 derailleur has a ratio about double that of your SRAM shifter, so every shift would jump nearly two cogs.


There's a bunch of other stuff that goes into it as well, but that's the simple answer.

nonhunner

Ah I see. So it doesn't matter on a friction because I just adjust how much I shift. But because the brifter always pulls x distance that needs to translate properly into x distance based on pulley dimensions so that the lateral shift = 1 cog. Thanks! This is really helpful

KCT1986

In simple terms, it is not really about pulley dimensions, but the pivot action of the parallelogram (the main body) and the attachment point of the cable. The design of those determines the lateral movement of the pulleys.

Something similar effects the front derailleur also. Older FDs used more cable pull and the newer FD used less pull to match cable pull of integrated brake/shifter units. The ratio of the cable attachment arm length relative to the pivot points affects how much the chain-cage moves. See below for the SRAM FD, with very short arm. Older FDs have a longer arm and thus needs more cable pull. This applies to both SRAM & Shimano integrated shift units.

nonhunner

Wow cool. Thanks for giving such a detailed explanation. That does sort of explain why a big long pull on the front derailleur is equal to a tiny one on the rear with friction shifters. More personal interest questions incoming! What was the reason for this? To pack more into the brifters? Because it's hard to do long pull on things that aren't friction shifters?

Kontact

I think you'll find SRAM FDs are closer to older Shimano designs, while current Shimano FDs have very long arms.

But it's a good example of what is going on with actuation ratios.

KCT1986

Yes, the pictured SRAM is reasonably close to pre-11 speed Shimano brifter compatible road FD, (8/9/10). If the OP's is much older, (FD-62xx)? it had longer pull needed than used on older brifter, (including SRAM 10 speeds).

nonhunner

This is the exact one I have

https://www.ebay.co.uk/itm/285549278...mis&media=COPY

KCT1986

Here's something I posted a few days ago. Pull a picture up of an early versions of Shimano's brifters, the ones with shift cable coming out the side, to visualize it.

The difference in actuation ratio for FD between MTB & road really happened when road went to brifters. A possible reason is that early brifters had the shift unit in the very front of the pod. To keep the old actuation ratio of road and MTB (more cable pull), the cable take-up spool would have to be large or the 'throw' of the lever would have to be longer. A large spool would make the 'bulbous' look of the early brifter even worse, (picture a ST-6400 with an even larger 'knob' behind the name plate). Or a 'throw' that would have you push the A lever (larger lever) much further to move the FD to a larger chainring. This is my take of why brifter era FD use a shorter cable pull.

Kontact

That's a rear derailleur. We're currently talking about front derailleurs.

nonhunner

AH ok. Fair enough. One of the comments though noted that I might not need to change the front. Is everyone basically saying that I will need to change that too?

Kontact

I don't follow. Road actuation ratio hasn't changed since the late '80s until 11 speed. Mountain ratio for the FD has been different since the '80s. The road front only changed with 11.

Kontact

I think it is possible you might not need to. The cable arm on that old 6200 derailleur is similar to the SRAM length.

Iride01 

Your Shimano 600 Arabesque came from back in the day when there were 6 and maybe 7 speeds on the rear. The stack of sprockets was only 31 mm wide give or take a few mm on a 7 speed and only about 28 mm on a 6 speed. All depending on brand. A 10 speed cassette is now about 36 mm or better wide.

So it's a little unknown if your old RD will traverse that distance. As well, if it is a short cage RD, then it's max low cog will probably be 28 teeth or less..

Kontact

Aside from the fact that it is a pre-index derailleur and will be very hard to get it to index even with the right throw.

I have often been surprised what works. I have a Nuovo Gran Sport from the 5 speed era that will easily do 8 speed, and I tried a Shimano Light Action index derailleur from the '80s that would not.

But if the derailleur wasn't designed for index, it usually won't track the cogs close enough to work alright. The exception being old Suntour - but you still have to modify the actuation.


Derailleurs are relatively cheap. Not a lot of reason to mix and match once you've spent the big money for the brifter.

Iride01 

I most definitely agree with you on that.

I still marvel at the length some go to so they can avoid indexed shifting. I was very late to the party for indexed shifting and the mantra being preached about the horrors of indexed and the greatness of friction by those like me that had never tried it had me fearing the move.

However once I got my 11 speed Shimano 5800 to put on a old '91 Schwinn Paramount frame, I realized that indexed shifting was none of the fearmongering that was put out about it by others that evidentially had never tried it, yet bad mouthed it anyway.

I'd never willingly go back to friction shifting.

Kontact

I am the opposite. I have always had indexed bikes, and experimenting with excellent friction shifters and hyperglide has made me appreciate how well a modern friction set up can work.

KCT1986

No, there was a change in the early 90's with the 1st brifters, a higher actuations worked better since it pulled less cable. During the transition (early 90s), Shimano made a couple of versions that was designed to handle brifters, but also would work like the prior version if used with DT shifters (to maintain similar feel?). Pictured is Shimano's recommendation for set-up. DA also had a similar dual position version, then a later third version that had a shorter arm for brifters. 105 & RX100 FDs were redesigned with the introduction of brifters, the 'leading action' style was replaced with a standard lateral movement only style. Shimano road RD up to 10 speed used the higher actuation.



Here is the 'leading action' style that required more pull since it moved diagonally and wasn't ideal for brifters. Replaced with FD-A551(?).

KCT1986

Whether you will need to change it will depend on the dimensions of the pivots. The length of the cable attachment point to the pivot vs the same pivot to the cage attachment will affect the movement amount of the cage. Compare what your RD pivots look like to the pic of the SRAM. The SRAM brifter pull only a little cable so if can't actuate the FD enough the cage won't move over the outer chainring.

You could possibly 'fudge' it by doing something like the Shimano diagram, (attach to the opposite side of the bolt), but don't know.

It's always easier to just match brands.

Kontact

Actually, that's what I was referring to. Those angled shifting derailleurs were designed for friction shifters and used more cable than previous and later designs. When Shimano came up with brifters they got away from them, but like the 7400 alternate cable routing scheme, they came up with a workaround so everything wasn't immediately obsolete. But all "index derailleurs" had the same cable pull, which I guess includes the ones shown here with alternate routing.

Point is, Shimano has only had 2 index road FD cable pulls, so you won't encounter a road shifter that isn't one or the other.

KCT1986

Yes, the change was with the beginning of brifters, (which you just confirmed), this was early 90s, not the late 80s you posted. So the change coincided with brifter, as my older post stated.

Kontact

The first brifter was 1989 Dura Ace, and that FD did not have the long geometry of the Sante, Ultegra, 105 and Exage derailleurs. When other brifters came out, they kept the DA FD pull ratio.

KCT1986

The ST-7400 first hit the Shimano catalog for the 91 model year (catalog page attached, note the arrow on the FD arm). Protos were around earlier but no info on what they were like. If the protos uses the same pull as the commercial model it would have used some type of shorter arm FD. If it used the older long pull FD, it would need a larger cable take-up spool or longer 'throw'.

The other brifters did use the shorter pull and new FDs, my point in my prior post about why the change was made. Reread my reasoning for the change in FDs.