I have an older (1999) Hardrock with the original rear derailleur. It's a Shimano MC-18 lower end RD that has performed fairly well all these years

I believe I have already figured out the answer to my question, but would appreciate other expert input. My question is this: when adjusting the high (7th gear) screw, what positioning of the upper/guide pulley should be used?

I assume on most (if not all) RDs, the upper pulley has room to slide from side to side. On my RD, this is ~1/16-3/32 in. (or ~1/16" either direction from center). Given that adjusting this pulley means to align it with the top (in my case, 7th) gear, where should this pulley be positioned when doing the alignment. I've placed the pulley as near-center as I can tell and the result has been OK. However, when I place the pulley to its far-outside position and then adjust, that seems to work best.

Have I got this right?

Here's what the Shimano RD adjustment guide says:

1. Top adjustment

Turn the top adjustment screw to adjust
so that the guide pulley is in line with
the outer line of the smallest sprocket
when looking from the rear.
After this, install the chain.

...but it doesn't mention where on the shaft the guide pulley should be placed


Thanks and cheers...Steph

I adjust both limit screws for the tightest adjustment which allows for crisp shifts, and no looser, when shifting by pulling the shift wire by hand, as suggested in this procedure: https://www.parktool.com/blog/repair-...nts-derailleur

I could not tell you what position the pulleys are in as I never look at them while making the adjustments, I adjust for shifting performance only.

Just adjust it as above and then modify as needed for operation rather than what it looks like. There's no exact position that always works - what important is functionality.

Thanks for the responses.

Turns out I've been using a combination of the Shimano RD adjustment guide and the Park Tools RD adjustment process (I'd read the Park Tools material in the past and thought I'd made a copy...have 1 now

What I realize I need to do is restore the threadlock coating on both the high-Low adjust screws that I remember having on there at some time in the past

Again, appreciate the help (and validation).....Steph

Hey, steph!

Actually, I wouldn't worry about the limit screws backing themselves out; they typically don't exhibit that trait. As cny and dsbrantjr have said, it's more about functionality than exact dimensions. Personally, I tend to look at the outer DR cage and use the sound of the chain on the pulleys more than anything when adjusting a rear DR... sound will tell you quite a bit!

#1) get the derailleur hanger Eyelet in alignment. Bike Shop Service, tool.

Stroke limit screws , ar relatively explaining their function..

the pulley at the ends of the travel range , stop directly under the 1st and Last Cog of the rear cluster..
in the same plane, as viewing the cassette edge on, from the rear,

fitting a new RD I do this before installing the cable..

Alan,

Nice to hear from you....how's things in CO these days? We're having great riding weather out here in the Bay Area Mid-70s (up to low 80s by this weekend).

Thanks for chiming in. After I "solved" the problem of an "incompatible" cassette a few months back, the bike has been running flawlessly....until about 2-3 weeks ago. Then I noticed some top/7th cog chain-skipping had returned. I did a readjust and the problem seems to have disappeared (for now). That was when I noticed the H adj screw had shifted off the original setting. I also noticed that when the RD is not on the top or bottom cog, the H or L screw feels like it unscrews fairly easily (almost no friction/drag on the adj screw). While I agree this normally shouldn't happen (maybe because of my bike's age), it seems in my case it has I added some threadlock this morning and hope that will take care of it...I'll know for sure tomorrow morning.

As for doing the adjusting, I do use the Shimano adj info only as a starting point. Then I do go more by feel and sound to get things more fine tuned....

Cheers....Steph

steph,

Glad the weather is cooperating! It's been quite pleasant out here in Denver, but I bet the hot temps are coming real soon!

Hopefully the drop of Loc-Tite will keep the limit screw tight; it should do just fine.

Have a great weekend!

Alan

When I want a screw to not move easily I've generally just very slightly damaged the threads - fairly permanent solution.

First off...for Alan....If you've been keeping up with the weather here on the West Coast, we are now into a heat wave, of sorts (like someone turned on the Summer switch back on June 21st). Been upper 80s/low 90s for the last few days here in the Bay Area and will continue on thru Mon/Tues of the coming week (Strong heat advisories). When you can comfortably wear shorts (not talking about a style issue in San Francisco, we know we're in for some sort of hot cycle (I live ~40 miles south of SF and we're usually 10-15 degrees warmer). Our good news is that this causes a marine layer (low overcast) to be sucked into the Bay Area and that usually cools us down til the next cycle. No complaints...I could be living in the midwest/on the east coast

OK, back to busy-ness...thought I'd circle back around on this RD thing. I've been riding and adjusting and riding for the last 2-3 weeks and, while it's gotten better, I didn't hit "near-nirvana" until my ride this most-recent Friday. I'll be doing a longer ride Sunday AM, so it will be a good test. I think I'm there, but I may need to do one more slight twist of the screw to be sure.

I certainly have learned something about my bike. However, I also think I've learned a bit more about myself. I realize I am overly cautious/conservative when it comes to fixing my bike (also that way financially I was so very much concerned about under-adjusting the top gear stop screw so the chain didn't walk off the cog that I believe my initial (re)adjustment (after adding the threadlock) put me on the wrong side of the "sweet zone" for setting it up.

I plan to be less "engineer" (which I am) and more intuitive and touchy feely from this point on when it comes to making adjustments (Big Grin!!)

Cheers....Steph

A 1999 bike. That's interesting.

I seem to remember a bulletin from Shimano during that era suggesting adjusting the upper pulley to the outside of the smallest rear cog just as you indicated. That was a long time ago so take that for what it's worth.

A couple of additional points:
1. I'm a big fan of checking derailleur hanger alignment. It's common for a bike that old to have had the hanger bent inward a skosh. No other adjustment will correct a misaligned derailleur hanger.
2. I adjust derailleurs to be functional. If it works best adjusted to the outer edge of the cog - that's OK with me.

Retro Grouch (gotta love that name

I appreciate the input.

After sleeping on it and doing a longer ride Sunday morning, I realize I needed to be a bit more "zen" (and the art of bike maintenance..sounds like a great title for a book and much less anal about it.

The bike is a Specialized Hardrock and has done very well (20K+ miles) despite the fact that I didn't do a very good job of maintenance on it for the 1st 2/3rds of its life with me I posted a thread late last year about a skipping problem that showed up after I replaced the cassette and chain. Had never had that problem before. I eventually concluded it was a cassette "compatibility" problem and got a different cassette. Went thru the adjustment process and had been riding w/out skipping for a number of months. Then it showed up again more recently without having done anything to the bike (thus, this thread) and I thought it might be the limit adj screw "self-adjusting". So I added the threadlock and began readjusting. After my ride yesterday morning, I realize I'm not yet there (still shows up in 7th gear very occasionally on flat ground, more of a soft "chunk" than a skip, and definitely when I stand on it going up over a bridge.

Am not sure what's going on this time, but I'll continue to adjust and test and see if I can hit that sweet spot again.

To your points...I may need to continue to move the adj towards the outside (since I seem to have started more towards the inside and have been adj ~1/8th of a turn out before each ride...I'm assuming the skipping is because of the chain "catching" on the next lower gear).

Re: Hanger...the RD mounts directly to the frame. There is no extra metal piece/hanger that goes between the RD and the bike. However, I have noticed that there may be too much play in this area (given the age of the bike, I had been thinking about a new RD and this may be the moment) and this could be the same as a misaligned hanger with no way to readjust.

Re: Functional...this is my zen approach. Reached nirvana once....need to see if I can get there again. Otherwise, time for that new RD.

Thanks again for the thoughts.

Cheers...Steph

The good news is that's a steel frame bike. They tolerate the following better than aluminum bikes do.

1. Shift into a gear combination that makes your derailleur arm point straight down.
2. Prop your bike up vertical and look at it from the back.
3. If your derailleur arm seems to point toward the wheel - that's it. It should point straight down.

On a 7 or 8-speed I can eyeball it back into alignment so that it's "good enough." On a 9-speed, I need to use the alignment gauge. If you're up for trying it without the gauge:

1. LEAVE THE DERAILLEUR IN PLACE! If you remove it, you can ovalize the derailleur mounting hole and I don't know how to fix that.
2. I either clamp a big Crescent wrench around the derailleur and mount or, sometimes, I can do it with just my hands.
3. Just armstrong it back so that the derailleur arm points straight down.

Good luck.

Thanks for the suggestions.....

I did a RD "vertical integrity" check not too long ago. I used a level to get the bike as vertically aligned as possible and then used a modified "plumb" doohickey to check the RD alignment. Access to more accurate gear notwithstanding, the RD looked pretty well align.

Your mention about "ovaling" the mounting hole....related to a good part of the reason why I'm thinking new RD....is that I never oiled/greased the RD bushing (where the bolt mounts the RD to the frame) until last year (19K miles, 14 years I took the RD apart to check it out and regrease/oil as needed. When I did, I noticed a small bit of binding on the bushing where the RD mounting bolt goes thru and into the frame. I tried oil, no help. So I took it apart (I also regreased the rear wheel bearings and replaced the freehub) and attempted to ream it softly to clear the roughness. When I put the RD back together and remounted it, it moved much more freely, but there was now noticeable play in the RD. However, I was still able to find the RD's sweet spot and had been riding without any skipping problems until recently. The only thing that changed was the threadlocking (which meant removing, coating and reinstalling the adj screws).

I will continue to adj/ride/adj/ride until I've reached the point where the problem is gone...or the chain comes off the 7th gear cog In the meantime, I'm checking out new RDs

Cheers...Steph

Update (to the update...)

OK, so the day after I ordered the new RD, I decided 1 more try on adjusting the current RD. On yesterday morning's ride, the bike performed without any skipping, "soft chunks" (or even "chirps

Initially I thought that maybe I could have held off ordering the new RD...but only for a moment. After 20K miles and 15 years (of questionable maintenance on my part and the fact that I want to go to 8-spd (which requires a wee bit tighter tolerances) tells me it was time. Yeah, I could have waited. However, with the preciseness which seems to be required on the current RD, I'm sure I'll be better off just going with all new rear chain drive parts.

Again, thanks for listening and for the help. I look forward to more great riding.

*************************************


Just wanted to circle back around with an update......

After spending the last couple of weeks trying to find the RD 7th gear "sweet spot" again, I've come to the conclusion that I was lucky up til I cursed myself by threadlocking the RD limit screws. Can't quite get completely rid of the "soft chunks" on flat ground and skipping when going up a hill. And I've pretty much adjusted the high-gear limit thru its range. Also, over the weekend I realized there is just too much play in the bushing(s) (my own doing) where the RD mounts to the the bike (even tho I know these lower end RDs are reasonably forgiving, it escapes me how I ever was able to get it adjusted so well this most recent time). So, as a result, I "pulled the trigger" and ordered up a new RD. Decided on the RD-M410 since I've seen it mentioned as replacement for the original MC-18. The bike's too old to go with a more upscale RD, and the lower-end RDs just seem too cheap.

At the same time, I ordered a new freehub so I can go to an 8-speed cassette. It's not that I want more gears (only use the top 5 anyways). It's that I've noticed the options are ever more limited for 7-gear cassettes. Of course, in a few years, I'm sure I'll say the same about 8-speed, as well

Again, thanks to all for the help....

Safe riding and cheers....Steph