daveed

My barend friction shifters shift the chain effortlessly pedaling forward. Yet when I backpedal I'm getting all sorts of noise and chain slop. This has been happening ever since I messed around with the screws on my Deore derailer. Did I do something wrong? And how can I fix this problem?

nfmisso

Don't EVER "MESS AROUND" with something you expect to keep working.

Yes - you "messed around".

Take the bike to someone who knows what they are doing, or learn yourself.

Davet

You're shifting while pedaling backwards? Doesn't work under the best of circumstances. The derailleur isn't designed to work while doing that.

blacknbluebikes 

not clear since you reference shifting - hope you're not trying to shift while backpedaliing, that's not ever going to work well. if you're just backpedaling: there should be no problem when you're in an "easy alignment" such as mid-rear-cog and inner front chainring. If there is a prob, it's most likely the rear derailleur cage (two small geared wheels) dancing around. Most likely a lube problem, but could also be related to old spring losing tension. Spray the heck out of it with a spray-lube like T-9 (not wd40) and work all the articulations. wipe, re-spray, wipe, re-spray. If that doesn't solve your problem, go see the mechanic at the LBS.

p.s. the little screws on the derailleur are "limit screws." study up on derailleur adjustments HERE

Gresp15C

As mentioned above, I assume you're not trying to shift while backpedaling. I'd check to make sure the derailleur pulleys are running freely, and that the chain itself is nice and limber -- and not stretched too much.

rm -rf

Sorry, I'm not sure how to fix your backpedal problem.

But, you need to redo your derailler adjustments right now.

The two screws keep the chain from running off the big or small cog.

It's critical that they are adjusted correctly. Otherwise the chain can go into the spokes, the derailleur arm catches on a spoke, and rips the derailleur off the frame. If you are lucky, only the derailleur is trashed, but often the frame is damaged too.

This Park Tool adjustment guide is easy to follow: Rear Derailleur Adjustment. Start at the beginning, and don't skip any steps. When you are done, you'll know how to set up the derailleur. And how to make small adjustments so that the chain is centered on the cogs.

cny-bikeman

When pedaling forward the derailleur guides the chain onto the rear cogs. If it's off-center on a cog it will usually just make a bit of noise. When pedaling backward there is no such guide (at the top of the cogs) and in addition the chain may be coming onto the cogs at quite an angle. In addition if the derailleur is not well centered on a cog the chain will not feed cleanly onto the derailleur pulleys. All of those factors can cause significant noise, even if you are not shifting at the time.

Finally, if there is excess friction in the freewheel, derailleur pulleys, or chain you will have chain slop and other problems even when the derailleur is aligned under the cog.

Backpedaling should be avoided except when getting the pedals in place when coming to a stop.

fietsbob

Which screws did you mess with ? the H/L stroke limit screws or the B screw ? Why did you do that?




An IGH with no chain tensioner , just a single speed/fixie like chain will be OK going backwards .





./.

juls

May have a gunky fw or fh. When you walk the bike backwards does it still happen? I lubed my fw when this happened to me. Just another thought.

FBinNY 

Read CNY's post again. He covers your problem well enough that I won't repeat it.

Also note that the limit screws on the derailleur, ONLY affect their respective terminal positions, and do absolutely nothing to the middle positions which are cable controlled only. By comparison, imagine an elevator, which has protective stop switches at the top and bottom of the shaft to keep it from overrunning and crashing. The elevator will run normally between all the floors, without these switches coming into play. However they can affect the top and bottom floor positions depending on where they're located.

One other thing that might be an issue is the "B" screw setting. If you adjusted it so the upper pulley is too close to the sprockets it might cause extra friction. You don't notice it riding because it's small extra drag, but it can cause the upper loop to slacken when back pedaling.

Now a WARNING

The limit screws prevent the RD from moving beyond the inner and outer sprockets. If you moved them you are at serious risk of shifting the RD into the spokes when shifting to low. This can cost you the RD. wheel, and possibly the frame so make sure it's set correctly. If you don't know how, find tutorials on the net and if still not 100% sure it's right, have a pro adjust it for you.

fietsbob

OP said 'friction shifting'

NB: if the RD guide pulley is not directly under the cog ,
and that cog is not one of the few right in the middle and so in the best, straightest, alignment
with the chain rings in front,

you should not expect the chain to stay on when the pedals turn backwards .

Grab the rear brake to lock the wheel pull the bike up and back straight up ,
turn it around 180 degrees , then it will be going forward on the backwards path.





./.

Homebrew01

Yup.

Quick fix, don't pedal backwards, especially if cross chained.

Homebrew01

The limit screws affect how far the derailleur can travel, such as into the spokes or not.
Not related to pedaling backwards.

daveed

Exactly, Homebrew! (I'm NOT shifting while pedaling backward, and I typically do NOT pedal backward in any case. It's simply that when I do I notice slop and clanging. The chain does not ship off one gear and onto another; it's just noisy. Problem may be the B screw. My RD shifts are dialed in nicely btw. Thanks.

FBinNY 

I mentioned the B-screw possibility earlier, and you can do a simple eyeball check to make sure that there's about 1/2" of daylight between the spockets and upper pulley. Note that if it's a B-screw issue the problem will manifest only on one or two sprockets rather than across the board. It will also be consistent on those sprockets.

I suspect that there's nothing wrong (except maybe for the limits which you fiddled with and should correct) and it's simply poor trim. Pedaling forward an imperfectly trimmed RD will work fine, though with a bit more noise and drag. However when backpedaling, that small error can push the chain sideways on the upper pulley and the slight added drag is enough to slacken the upper loop.

There's no harm in back pedaling as long as you don't do it enough to completely slacken the upper loop and drop the chain.

daveed

FBinNY "fiddle" is a much better way to describe what I was doing. Thanks for the helpful explanation. I'm betting I screwed up the B screw.

corrado33

Unless you unscrewed it all of the way, the b screw shouldn't adjust how well the chain goes through everything backwards.

My bet is a gummy freewheel causing slack in the chain when you pedal backwards. I see it all the time.

FBinNY 

While a sticky freewheel/freehub is a common cause of the problem, the fact that it started immediately after the OP made some adjustments hints at a likely connection between the two.

Rule number 1 of diagnosis is "what changed?", with any change immediately before a problem being the No.1 suspect.

Of course, it could be a coincidence, but coincidences are always suspect when making a diagnosis. Then again the next question might be "What led you to fool with the adjustments in the first place?" The answer then might lead to the suspicion that it was sticky freewheel all along.

mstateglfr 

Remove freewheel.
Spray wd40 into the freewheel.
Spin the freewheel.
Repeat a few times.
Wide the freewheel dry.
Reattach freewheel.


Simply sounds gummed up.

L134 

I will sometimes backpedal slightly, particularly on a tandem, when coming to a stop just to make sure the rear derailleur is properly centered on a rear cog because I can feel as well as hear if the rear derailleur is a tad off. If so, I adjust the friction shifter a bit to get things lined up so I can get a smooth start. Maybe you just need to tweek the derailleur position because you didn't get a good clean shift.

Tunnelrat81

Actually, depending on the cassette size, this may not be true. When my wife's bike was running a 12-27 cassette, I had to run her B-screw almost all the way in to avoid additional noise. I was able to relax it back a bit when I moved her to an 11-25 cassette, but it's still nowhere near all the way out. Many bikes these days (most I'd venture a guess, with non-racers riding smarter [lower] gearing than yester-year) are running cassettes w/ larger than a 25t cog, which means many people are likely to need the B-screw to be in a bit to keep the jockey pulley from sandwiching the chain up against the larger 1-2 cogs.

The B screw absolutely can affect how well the chain goes through everything, forwards or backwards, even if it's not all the way out.

-Jeremy

cny-bikeman

As FB noted, the fact that the problem started after changing the derailleur adjustment points to more than a gummed freewheel, and as I noted chain sag can occur for other reasons. In addition merely "lubing" a freewheel with WD-40 will result in a noisy freewheel and one that is vulnerable to rust. It should be lubed afterward with a heavy oil such as Phil Wood Tenacious.

mstateglfr 

Yes. Spend $10 for 4oz of oil for a component thats less than $20.
Might not be gummed, true.

cny-bikeman

"....should be lubed afterward with a heavy oil such as Phil Wood Tenacious." If you already have it, great. If not the such as applies.

Homebrew01

A few dribbles of motor oil always worked fine in my freewheels.

But does OP have a freewheel or cassette ?