I am trying to upgrade my 85 Ironman to 9 speed. I picked up a set of wheels with Shimano 600 7 speed hubs and Mavic MA40 rims. I got a 8/9/10 speed freehub and swapped it onto the real wheel and redished the wheel for the 130mm spacing.

I then installed a new 12-27 9 speed cassette and a new 9 speed SRAM chain.

When installing the chain, I tried to use the large-large plus two approach. But to be honest, I am never really sure I am doing that right.

And when I was doing it sure seemed like maybe the chain was a little long. When in small-small anyway. Large-Large seems to look about right.

Maybe the shimano 600 RD can't really handle a 12-27 cassette with 53/39 chainrings? If that is the case I should probably just shorten and avoid the large-large combination, which is probably a good idea anyway.

Here are some pictures I took as set up:











What do you think?

Looks to me like the chain length may be okay but the RD is at an odd angle. Any adjustment screws to rotate it counterclockwise at the pivot?

what is the part number on that rear derailleur? it looks like the RD-6207 i have but with a black center part as opposed to silver. The RD-6208 is black but says SIS on it too.

btw it looks like your wheels are right at the front of the drop outs.. not sure if that is safe (it might be) but i'd back it up a lil

looks fine to me. If the small small feels odd to you, tension the chain a bit with the B screw.

oh so thats what that screw does....

Or just turn the dopout adjuster screws so that the axle moves back in the frame a few mm. My examples of the 6207 don't have B-screws.

Really it looks right, now. Perhaps the chain is slightly tight in the big-big photo. That would be the state to look out for.

Your chain length looks good. DON'T shorten it. It's a big mistake to have the chain so short that it won't go on to the big-big combination. You think you'll never go onto that combination, but you eventually will. Don't ask me how I know this. At best, the chain will go on and get stuck, meaning you'll have to haul out your chain tool to get it off. At worst, you'll break something or make a bunch of shredded metal.

I'd slide the axle back a couple of millimeters also.

B-screw adjustment? Maybe if you've shifting troubles.

oh, i thought that what the axle rotating screw was called.. what is it called?

I used it to tighten the tension on my 1x7 to discourage it from throwing the chain, hope it (and some other things) work

In the pic you can see screws that go through the back of both dropouts. These adjust where the axle sits.

The B-screw goes through the derailer and the end of it presses against a little nubbin on the drive side dropout. Screwing it out increases chain wrap around the cogs.

ok, so the b screw is what i thought it was

The "big-big +2" method has never failed to deliver the proper chain length for me.
I loop the chain over the biggest cog and chainwheel, WITHOUT running it through the rear DR, and add two links.

I agree with frantik and the others about the need to budge that axle rearward in the DO.

Cool. It does not rotate axles, however.

I totally tweeked the drive side dropout set screw (collateral damage from a RD explosion) on my Pinarello a while ago and decided to yank both of them. A couple of turns on the B-screw and all is well.

The method that works well for me is to put the chain on the large chain ring and the smallest cassette gear and the two dérailleurs idler wheels will be aligned vertically.
Here are two videos that show how.
Ed
https://www.cpamyspacelayouts.com/roa...or-road-bikes/
https://www.youtube.com/watch?v=bsU2nEf2Tpc

it causes the derailleur to rotate on one of the axles... i dunno, i just know (now) that it's used to tension the chain

The chain length looks proper to me.

+1

Why is that? The big-big combo should NEVER be used. There's no good reason to use it. EVER. Same goes for small-small.

Thanks for the all the comments.

I checked the RD. It is a 6207. Several people said I should adjust the B-Screw. But I don't see one in the normal place. Does it have one? And while playing around with this I noticed that the RD is slow to spring back into the position when you pivot it forward (counter clockwise on the RD pivot). It is like the pivot is all gummed up. It does spring back eventually, but very slowly. I compared it to a 105 derailleur on another bike and it is night and day difference.

What can I do, if anything to fix that?

And I took your advice and moved the axle back. One of the adjusters was stuck, but I was able to get it unstuck.

That sounded like a good idea, especially when you consider that it is running 130mm spacing with a 126mm sized axle. I would say I moved it back between 1/16 and 1/8 of inch.

Jared

The single most important thing in regard to sizing a chain is to make sure it's long enough to safely shift into the large-large combination. If not, and you have a brain lapse and shift to that combination, you can bend and/or break your rear derailleur, break your chain, have the derailleur thrown into the rear wheel where it will do nasty things, and can even damage your frame. As others have said, the big-big plus two (one inch) method is the surest way to size a chain and know it will be long enough to cover the big-big combo, it gives you the shortest possible chain length that will safely cover big-big. If it turns out that the chain is a bit too long for the derailleur to handle in regard to taking up the slack in the small-small combo, that's not near as big a potential problem as a chain that's too short to cover big-big. Of course, extreme cross chaining ( small-small and big-big) should be avoided, but brain lapses do happen.

You've probably seen this already, but here's Sheldon's excellent instructions on the big-big plus one inch method, with pics:
https://www.sheldonbrown.com/derailer...ent.html#chain

Agreed, it should never be used. But the law of averages says that it will eventually get used by mistake. You know, you're thinking about something else, forget what gear you're in, or just accidentally push the lever the wrong way. This is the essence of Murphy's Law, which is often looked on as a sort of joke, but is in fact a serious engineering principle: if something can go wrong, it will go wrong. Systems should be designed (to the extent that it's possible or convenient) so that things CAN'T go wrong.
Infallible riders don't need to think about that kind of thing, since it by definition cannot happen to them. I'm fallible, myself, so I do think about it.

It is the OP here again. Anbody have a suggestion as to what I should do about the RD? See my post above. I am not really sure why it is not springing back.

I looked in my parts stash, and I do have a dura ace 7700 RD that would look good. But looking it up on shimano tech docs it says it can only handle up to 26 teeth on the cassette and has a total capacity of 26 teeth.

As I said above, I have 12-27 cassette, and a 53/39 chainrings, so I need 29 teeth of total capacity. I have heard that shimano under-rates their products, so maybe the 27 teeth on the cassette is ok, but what about the 29 teeth of total capacitity versus the rated 26th teeth?

Jared

i made a ghetto singlespeed one day for fun, but the bike had verticle dropouts so i couldn't tension it correctly. the second time i rode it, it derailed onto the next biggest gear as i was pedaling. luckily i stopped as soon as something felt wrong, but it jammed and i had to use a chainbreaker to remove the chain.. when i broke it, it was under a LOT of tension and snapped like a rubber band.. luckily nothing and no one was damaged

so yeah, definitely don't make your chain too short

So that's how it works...dang, these are the reasons I read every day!

Ok, I think we all agreed that the chain length was pretty good. How can I get you guys to focus on the RD issue that has come up?

When you remove the RD, you will see a spring that goes around the pivot bolt. I'm not too familiar with the 600 RD, but you should see pinholes where the end of the spring enters the back of the RD body. By moving the spring to another pinhole and then re-installing the RD, you should be able to get more tension.