BikingViking793 

I'm working on installing a SRAM X4 on a bike with a 7 speed cassette. I aligned the rear derailleur hanging and when I put the derailleur on it wouldn't go anywhere near the smallest cog regardless of how far out the H-limit was. Strangely backing out the L-limit makes it possible to go to the smallest cog, but then it goes way past the biggest cog. I'm getting it close by playing with both, but what is going on here? This is my first SRAM install. Is there some trick here?

Iride01 

Maybe you have the high and low limit screws confused. If this is the correct manual then it's the inner screw that is the high limit, which on other RD's is the low limit. But on this RD it's the high.

https://www.sram.com/globalassets/do...ser-manual.pdf

see page 9.

Annoying when they put all the languages together on the same page. But it is what it is. Guess they didn't want to waste ink and paper on the duplicated graphics for each language.

Here's all the service info they show for that RD line.

https://www.sram.com/en/service/models/rd-x4-a1

BikingViking793 

This derailleur is very clearly marked with H and L. If I screw in the L limit far enough so it won't go off the largest cog, it won't happily go into the smallest cog. If I back out the L limit it goes into the smallest cog, but then it can go over the largest cog. If the L is way out, the H does seem to work properly.

FBinNY 

It's the cable that positions the derailleur. So backing out the outer limit will not move the RD out unless cable slack allows it.

BTW, for many years limit screws were unmarked. Many old timers like myself, still prefer to look and confirm which is engaged at either end of the travel range.

BikingViking793 

Yes, typically the L limit does not affect going into the smallest cog. In this case I need to back out the L limit in order to get into the smallest cog. When I do this, it then will go over the largest cog and into the spokes. Anyone with SRAM experience out there? So far, I'm not a fan.

FBinNY 

Disconnect the cable for a moment. Tighten both limits, while pushing in the lower body to take weight off.

Now, shifting only by pushing on the lower body, adjust one until you can shift to low gear (inner sprocket) but not overshift into the wheel.

Repeat with the other until the spring will shift to high (outermost) sprocket, but not beyond.

Once the limits are set, you can attach the cable and trim for best shifting throughout the range. Note that it may be necessary to fine tune either limit for best shifting on the road.

BikingViking793 

I rechecked my hanger alignment and I didn't find any issue. And it visibly looks quite staight I might say. The only way I get it working well in the smallest cog is if I back out the L-limit. I can see the L-limit screw is touching when in the small cog which makes no sense to me. It doesn't matter if the cable is off and the H-limit is back out all the way. I have to loosen the L-limit screw in order to get in the smallest cog without it being very noisy. But when I do that it will then go over the largest cog into the spokes. My only guess at this point is that this derailleur is bad. I can get it to go into all the gears ok, just the L-limit is blocking the smallest cog. Which of course makes no sense.

BikingViking793 

I can't get the angle right with a picture. Here it is with the chain on the smallest cog, you can clearly see the L-limit screw head. When in the smallest cog the screw is hitting that piece of metal just above the spring. So, I have to unscrew the L-limit for it to go into the smallest cog happily. Kinda seems like this new derailleur is defective and maybe there is some alignment issue making the screw hit that piece of metal when it is not supposed to.

BikingViking793 

I guess I should mention the H-limit screw seems to work as it should. So, if I back out the L-limit I can adjust the H-limit fine.

maddog34

why does it appear as if the small cog is nearly touching the dropout?

can you post a pic from directly behind the Cassette, in line with the gears, please.?

you may be exceeding the design limits of the derailleur.
there may be an incorrect axle set or locknut being used, or a missing washer between the Cone and jam nut.
a quick look at several bikes here shows a MINIMUM of 4mm between the gear and dropout.... and that minimum is on a Diamondback that began life as a 7 speed and was upgraded to a 9 speed, including a wider freehub type hub.......... all others were between 5mm and 6mm from frame's dropout to Gear face (not the Retaining collar).

and i've seen 8 speed freewheels that are simply too darn wide to be used without re-spacing the axle and redishing the wheel....

the previous derailleur may have allowed this setup to work, but the x4 is saying "no way".
check that clearance from the small gear's face to the dropout and let us know.

One other request.. please post a pic of the High limit screw when set to be correct.. do what is needed to the Low limit to make the high limit work... thanks.

FBinNY 

If you don't let the markings confuse you, do you have 2 limit screws, one that engages when the RD is inboard, and the other when it's outboard? If so, adjust them based on that rather than according to the markings. They act 100% independent of each other, so the fact that you're backing one out to shift to the smallest sprocket and it's affecting the other end, implies that you're probably adjusting the wrong one.

Follow the steps I outlined earlier and adjust the limits without the cable and you should be fine.

OR,

Take the time to find out EXACTLY where the "L" limit is touching the RD when on the smallest cog. If the tip is touching, and tightening it more prevents shifting to the small sprockets, then it's simply mismarked. Once you sort that out, use the same logic on the other. OTOH if it's not touching at the tip, where and how is it touching? is there something bent or misaligned?

BikingViking793 

There is plenty of clearance, and it is happily in the small cog, if I back out the L-limit.

BikingViking793 

Not miss marked. The L-limit does keep the chain from coming off the large cog when it is adjusted. But if it is in far enough that it keeps the chain on, it is blocking the chain from going fully into the small cog. The H-limit screw limits how far it will go on the small cog if the L-limit is far enough out. Derailleur seems defective in some way.

FBinNY 

Others and I are trying to help, but we're not there.

You repeat the problem, but fail to provide any useful or necessary insight.

Since the "L" screw lacks magical powers, it must (based on your report) be touching something when the RD moves outboard to the last sprocket.

So, when I asked EXACTLY how it's causing the problem, I meant for you to use your eyes and see how, where, and what it's touching to prevent movement.

I repeat the suggestion ----- OBSERVE, USE YOUR EYES (because we can't do so via the internet) and find out EXACTLY and SPECIFICALLY whst the problem is.

Maybe even take a close up photo showing what's touching when you can't shift to high.

BikingViking793 

Sorry, I explained what is going on in post #8 with a picture. The L-limit screw is making contact and blocking the derailleur from moving toward the small cog. I'm thinking derailleur is defective and not aligned correctly or something.

Thank you to everyone trying to help.

maddog34

"plenty of clearance".. is Not a MEASUREMENT.. Please Measure the gap... and a pic from directly behind the cassette will sure help too.

if you can't measure the gap with a ruler or caliper, you can insert ever-larger Allen Hex L wrenches until you find the largest one that fits in the gap Between the Face of the Gear and the Frame's Dropout inner surface.

FBinNY 

The picture doesn't show where. what, and how it's touching anything. You're there, so be a detective and look closely to see what's touching and see how it might be solved. For all we know from here there may be a burr or embedded debris that could be filed or cleared.

BTW if you haven't done so yet, REMOVE the cable and independently adjust the limits without it. With the low limit properly set for low, push the RD in and let it spring back hard a few times to find whether it can move far enough, and if not, why not?

maddog34

I have an x-5 in front of me right now.. the Low limit screw hits the Inner arm of the parallelogram, right at the pivot pin flare at the lower knuckle.... but only if the high limit is backed out too far.....

Conclusion: the Cassette and hub (an old Uniglide) is too far to the right, forcing the derailleur to attempt operating outside it's design parameters... being a 7 speed only makes things worse, since the low limit needs to be in nearly all the way to accommodate the 7 speed cassette's narrower overall width, and adjust for the probably too-far-right hub...
The fault is with the axle set, due to a previous Bad "repair" or rebuild, IMO.
the Previous 3.0 SRAM der. didn't have the reach problem.

solution: shift axle and spacing to the right 2mm (a guess) with a 2mm narrower long spacer on the left,and adding 2mm to the right.
long spacers for the left ends of axle sets come in 2mm increments, typically.. i have 12, 14, and 16mm ones in my axle parts box, as an example.......

BikingViking793 

Interesting. The spacing between the cog and dropouts seems very normal to me. I can put a 4mm allen between the cog and dropouts. This distance is consistant with the other two 7-speed bikes I have in the garage that I took a look at. Here is an image. Seems like a poor design if this much space isn't enough.

I moved the chain up a cog and could fit a 5mm allen between dropout and last cog.

maddog34

Thank you.. now..the problem is isolated to a SRAM Derailleur that is supposed to work with a 7 speed Cassette, but obviously does not.

solution: get a clue and quit screwing around in... THE SRAM ZONE Zone zone zonnnnnne... or find another 3.0, since the newer SRAM stuff kinda sucks, eh?

OR.. get rid of the outdated uniglide freehub wheel and swap on an 8 speed assembly...

what Right Shifter does your bike have on it?

one other possible solution... find a 1mm thick x 10mm ID washer and insert it between the Derailleur hanger and the Derailleur..... then see if that SRAM der. can be adjusted to fit your out-of-date uniglide cassette/hub.... worth a try, eh?

Something to look at on your project and the two other 7sp. bikes,, check the clearance from the Derailleur hanger to the Cassette,,, there may be a difference that has moved your project's der closer to the cassette...?

FBinNY 

Thank you for that. Now I understand the nub of the issue, though I am surprised.

Derailleurs typically can shift outboard to a sprocket about 8mm in from the face of the tab. That would allow a tab or dropout thickness of 5mm and 4mm inside clearance with 1mm margin of error.

Over the years, dropouts, along with hangers have gotten thicker, moving RDs outward w/respect to the hub and cassette. I suppose that Sram factored those thicker hangers into the design, and the OPs hanger is now too thin for that RD.

It's not a defect anywhere, simply a design or generational mismatch.

I'm of the "if it don't work, MAKE it work" school, so if it were mine, I might opt to carefully file where needed to buy myself the added travel, if it were feasible. Otherwise I'd thicken the hanger with a washer or shim to move the RD outboard 1-2mm as needed.

I wouldn't space the axle since there seems to be plenty of sprocket to dropout clearance already.

maddog34

The problem is that the SRAM engineers didn't consider things might not be exactly as they were in their shop.
And if the der. was being used on an 8 sp. cassette, it would work wonderfully... the 8sp. cassettes are about 4mm Wider, overall... so the Low limit screw wouldn't be screwed in all the way. to make it "work" for the 7sp. antique uniglide hub and cassette, and wouldn't collide with the inner pivot bulge.

maddog34

i just located a SRAM 3.0 Der. in my ample stock of used parts... Guess what? IT DOESN'T SUFFER from the design flaw of the newer Ders. It WILL Work fine with your antique hub and cassette! Cool, huh? Here's the Exact Model of Der. i just examined... https://www.ebay.com/itm/19500463911...Bk9SR975hN25Yg

FBinNY 

So, we know it's a generational mismatch. You and I offered the OP options to consider, so it's now up to him to decide to either make it work, or buy a different RD.

BikingViking793 

SRAM says it's for 7/8 speed. Seriously if it won't work in this application SRAM needs new engineers. I'll have to bring the bike in to the shop where I bought the derailleur and see what they can say about it. Seems like a really bad design.