Chain line issues...
 

My chain line was off by about 7mm (the cog was inside, or toward the middle, from where the chainring was) and was occasionally making noise and giving resistance.

I ordered some various sized hub spacers (3mm, 2mm, 1.5mm & 1mm) to work to improve the issue. I started out by putting on just one 3mm spacer. This improved my chain line to an error of only 4mm. The trade off is that the lock ring doesn't go fully onto the threaded hub. With the 3 mm spacer it's more like 90% threaded onto the hub. Will this cause any problems? I have been riding it like this and haven't had any problems yet with the lock ring coming loose. How far unthreaded can you go before expecting problems with the lock ring coming loose too easily?

Even with a 3mm spacer I still have some occasional (but thankfully less than before!) chain line noise & resistance. I'd like to add more spacers but I'm wondering how far I can go. I'm thinking to add a 2mm spacer and see if I have a better balance between lock ring & chain line. Then the fixed side would only be off by 2mm.

Incidentally, the freewheel side is already off (also inside) by about 2mm. I haven't taken the cranks off or the bottom bracket out of this bike yet so I don't know what's in there, but when I do, I'm hoping I'll be able to move the chainring in 2mm so that both sides would be more or less dead on. But until then it would be nice to solve this without investing in a crank puller &/or a new bottom bracket.

Any comments, clarifications or suggestions would be much appreciated! Rules of thumb about chain line tolerances would be helpful as well.

If it's relevant, my chain is 1/8" (is it true 1/8" chains are more susceptible to bad chain line issues?)

Post photos of your setup. It's difficult to give you an answer w/o seeing your situation.

Wait a minute. Is this bike a Thruster ? If the answer is yes, never mind my previous post and don't bother to post any photos. The answer is simple, throw the bike in the nearest dumpster. Problem solved.

Haha you're such an *******.

You're on the right track from the sounds of it. Unfortunately for you, with such a bargain basement bike, there's no set method or way to get the perfect chainline due to super lax quality control standards.
Ultimately it's going to be trial & error as you're doing right now.

Another short coming of the thruster is the crankset having a non-removable chainring. If it was removable, it would've helped to put the chainring on the inside of the spider for that 2mm you need.

Thanks for the reply Leukybear...

With the quality and quantity of replies on this forum prior to yours I figured trial & error on my own would be the way to go! :)

I'm beginning to wonder whether the noise I'm hearing is actually coming from the chain-line. Since a LBS guy said it was chain line I assumed he knew what he was talking about.

The sound/grinding/resistance always happens at the same point in crank rotation, so maybe it is something in the bottom bracket... I just ordered the tools to take it apart and see if there is a problem. We'll see.

Maybe in the mean time I'll get some more incredibly pleasant and super helpful replies like TejanoTrackie's above... :)

Check your chain tension aka check how tight your bike's chain is, with your crankset rotated to different positions.

Another thing about cheap bikes is the chainrings are not perfectly round or probably in your case with a crankset that has a welded on chainring, the chainring was welded on possibly slightly off-center.
Your chain from the sounds of what you describe, seems to be binding at high points of the chainring as a result of you tensioning your chain at a low point on the chainring.

Try finding the point of crank rotation where the chain is the tightest. Making note of that, loosen and retention your chain without moving the crankset position.

Leuky, I'll try that...

Ironically that was my first thought-- chainring. LBS guy told me it was more likely the chain line causing what I described. By the way, if anyone knows a competent, non-condescending bike shop in NJ/NYC area I would love to hear about it!

Anyway, I'll keep experimenting and I'll figure it out.

Thanks again Leuky!

Yes, 1/8" chains are less tolerant of poor chainlines. They were designed to operate exactly in line, long before anyone thought to have two or more cogs and change gears that way. Hence they will run rough at rather small chainline deviations whereas 3/32" chains were designed to operate well up to around 3/4" off.

An approach that would be cheap but a fair amount of work would be to respace the hub washers and redish the wheel. You may have a washer or two you can move from the axle on the right side of the hub and put them on the left side. You will then have to loosen the left side spokes and tighten the right side spokes to correct the "dish" of the wheel so it sits centered in the frame. This will move the entire hub to the right by whatever spacers you move from right to left. This requires no more than a coupld of wrenches and a spoke wrench but a fair amount of work and work that has to be done right our the results will be bad. If you decide to go this way, stay close here and maybe recruit a knowledgeable friend.

Edit: See if you can find a bike coop or bike repair shop. I;ll bet there is one in your area where you can find knowledgeable folk who regularly do work like this and won't be condescending.

Ben

I found a couple of bike co-ops in the area, but nothing super convenient. It will be a few weeks before I can get there, so for now I'm on my own...

I checked the chain tension and I was getting a fairly consistent tension throughout all positions.

I realized I was getting the grinding even with the chain off, so on to the bottom bracket.

I was able to remove the non-drive side crank (unfortunately after stripping the crank threads) using a hammer to hit the crank as the bb axel was resting on top of a nail punch sticking up out of a 2x4.

I removed the lock ring and the bearing cup on that side and found that one of the bearings was ground up real bad--maybe 10% ground off, and badly pitted and deformed. I'm guessing this grinding bearing was what I was feeling and hearing.

The problem now is I can't remove the drive-side crank arm, because the screw is not centered in the crank, so I can't get a 14mm socket inside to loosen/remove it. With that in the way I can't use the crank puller (not even sure if it is the right tool for these cranks--I had such a hard time getting it in before stripping it). Also, I don't think I have the right tool to get the drive-side bearing cup out of the frame. It looks like I need a very large cone wrench to remove it.

Since I'll probably replace the cranks and bottom bracket at this point anyway I'm thinking to cut the screw so I can remove it with a standard screwdriver.

Any better ideas? Am I missing something?

What? That makes no sense.

Yes. proper tools and a bike worth using them on...