mrmb

When chainline is off by a little and you already have the best bottom bracket, crankset and hub combo for the application, what should you do?

I see two logical options to address the issue....

1) Use a multispeed chain that has lots of flex to it.

2) Use a chain that is wider than the chainring and cog.

Questions.....

Is one option and better than the other?

Are there any other options I should consider?

mihlbach

I used to obsess over this stuff. If its only off a few mm, just ride it, it won't make a difference.

TimothyH

3) go for a ride.


-Tim-

mrmb

I notice on my bikes (I have 5 bikes total, all fixed) that have seemingly perfect chainline, the chains last much longer before they stretch by a noticeable amount.

On the other hand, my bikes that have chainline that is off a little, the chains stretch and wear out quicker. I can't think of any other reason for this than chainline.

Also, I have to believe that when chainline is spot-on and as such the chain is being run straight rather than bent sideways one way or the other, the system is more efficient (less flex, stretch etc. etc.).

Broctoon

Yes, there's one more option. As others have said here, you can choose to not worry about it. It doesn't really matter, unless it's off by a lot. A few millimeters is inconsequential.


You say your bikes with imperfect chain line wear their chains out faster. So, like, how fast? Are we talking about chains lasting a year or two as opposed to five years? If you wear one out every six months, that would be annoying and worth addressing. Otherwise, no biggie. Chains are cheap and easy to replace.


I have a really nice track bike. Pretty expensive frame that I got brand new. When assembling it, I started with a bottom bracket that should have given a perfectly straight line. It put the drive side crank arm too close, allowing it to hit the chain stay. So I went with a little wider BB spindle, and now the crank clears the chain stay, but the chain line is off by maybe 2mm. My other fixed gear bike is a much cheaper frame that I got well-used. Its chain line is perfect. The only difference I can detect is that the expensive bike's drivetrain makes just a little bit of noise, and the cheaper one is dead silent. Neither one is wearing out chains, but that's just my experience--your mileage may vary. I don't lose any sleep at all over them, just ride 'em.


Do you keep your chains clean and well lubed? Ride in the rain much? In dusty, grimy conditions? What shape are your sprockets in? These factors probably have a lot more to do with chain wear than alignment does.

Gresp15C

Are there any spacers or washers that would let you move the hub left / right in the dropouts? I had a pretty bad chainline (several mm off) when I assembled my hodgepodge of a SS bike with an old Bendix coaster hub and Schwinn road frame. So I got the chainline OK by putting different numbers of washers on the left and right, and then centered the rim in the frame by dishing the wheel towards the left. It's unorthodox, but I can't think of a downside.

Lazyass

You can put a spacer behind the freewheel.

Lazyass

You can also put spacers on the chainring bolts between the chainring and spider.

IAmSam

I decided to respond here rather than to your comment in the other thread - where you revealed that along with other nice goodies, you have a Campag Record Pista Crank on a Phil's bottom bracket...

I actually have the same set-up myself - but out of habit I run a 3/32" drivetrain so never use Campy's pista chainrings. I like nice bike parts as much as the next guy, but I do hate to spend a lot on consumables and I regard rings and cogs as consumables. Even with my cheap...errr...inexpensive 3/32 rings and cogs, I get tons of miles out of them and my chains.

What do you mean by "chainline is a little off?" I'm sure you must know that due to its unusual cups a Phil Wood BB has several mm's of built-in side-to-side adjustment? So unless your chainline is a lot more than just a little off - you should easily be able to get your chainline "right."

Good luck...

ThermionicScott 

Maybe you don't, then. What all do you have, and how many millimeters is it off?

The usual problem is that the chainring has ended up a few mm more outboard than the cog. If you have chainstay clearance to spare, one out-of-the-box option might be to have a couple mm faced off the BB shell so that the whole assembly can be moved to the left, with a BB spacer added to the left side to bring it back up to 68mm width. Easily "reversed" by placing the BB spacer on the right side again.

jmlapoint

For chain line that is off a 'little' bit I suggest 1/8" chain, 3/32" cog, and run the chain on the loose side.
john

mrmb

As for what I have, I have 5 bikes.

1 - campy crank and ring, phil bb, phil hubs, phil cog, pake frame...1/8 in gear

2 - sugino crank w/ surly ring, shimano un55 bb, shimano deore hub, bolt on cog, surly karate monkey frame....3/32 gear

3 - dura ace crank w/ ring that I cant remember, shimano octalink bb, white eno eccentric hub, white cog, surly pacer frame...3/32 gear

4 - andel crank w/ surly ring, shimano un55 bb, white eno eccentric hub, white cog, surly disc trucker frame.....3/32 gear

5 - sugino crank with ring I don't remember, rpm bb, shimano deore hub, bolt on cog.....3/32 gear

That said, #1 has a chainline that is near perfect, all the others are off by a few mm. I really like the non-consumable parts that I am using though and really don't want to make changes there. I would love to use wider chains to straighten this out.

Swapping hubs and cranks.......last resort.

ThermionicScott 

Which crank models and BB lengths?

The above is like saying "I'm having trouble with my Ford, what do you think it is?"

mrmb

I see your point, but the bb and cranks are not going to get changed. They are as close to ideal as is available. Additionally, I don't have the lengths and models readily available to me.

I think a wider chain would straighten this out.

In your opinion is using a wider chain problematic in any way?

mrmb

Why would it need to be on the loose side?

mrmb

Do you consider this noise problematic?

Any irregular noise would indicate irregular metal to metal contact which in theory should lead to accelerated wear to the parts involved. Right?

ThermionicScott 

I can't think of any downsides, and it might help a little. I run a 1/8" chain on 3/32" chainring and cogs myself.

Scrodzilla

Holy ****, man. Just ride your bike.

mrmb

I already am.

Did I ever say I wasn't?

Broctoon

Problematic? No. I think it's kind of cool. It's sort of a humming/whirring sound. More like an electric motor than any kind of grinding or scraping. I ride that bike hard, and the sound contributes to the whole experience. My much tougher and heavier fixie with big tires (Steamroller) is quiet as can be, and that's also fitting, because I enjoy casual cruises on it.

I have carefully inspected the chain ring and cog, and I don't see any signs of unusual wear, with several hundred miles on them. That's why I say I don't sweat the slight misalignment at all.

veganbikes

Ehhh it sounds like you are obsessing over something silly when you could just ride your bike. I don't think I have ever worried about chainline and I don't think I ever will unless I am doing some odd SS conversion on a bike that was designed as a geared bike and using a cog on a freehub body type of thing but I don't know why I would want to do that when there are so many excellent single speeds out there ripe for the picking.

Life's too short to worry about chainline.