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Chain for ‘flexy’ Singlespeed

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Discussion starter · #1 ·
I’ve had occasional chain derailment issues on my Pipedream Moxie in a specific instance for the last year+: higher lean angle, big power accelerations. I swapped from 11s to 9s chain hoping the wider plates and lower articulation would help (and it has) but I’ve still had it happen in that edge case once or twice. Chain tension is correct.

I’ve played with the bike lately and have narrowed it down to the plate-yoke chainstay design. It allows a surprising amount of lateral flex in that ‘leaned over, big mash’ situation. That flex is nice in chunky corners, but losing a chain really sucks. I’m not really interested in a derailleur style tensioner yet, but that may be the fix (outside of a frame swap).

My question is: would a dedicated SS chain be less or more apt to derail in the event of chainstay flex? It seems like a shifty chain might articulate better to accommodate misalignment, but it also has chamfers to encourage a jump.
 
Discussion starter · #3 ·
Fearlessphil said:
Have you tried measuring your chainline and going through the calculation to make sure it's absolutely straight?
Click to expand...
Good thought. Near as I can measure they match, but it is a left turn thing so bumping it inboard another ~mm might be worth a shot. It wouldn’t shock me if the frame isn’t dead-nuts aligned, either, and measuring from the dropout wouldn’t catch that. Eyeballing looks good, but I also doubt my eyeballs are mm-accurate.
 
#4 ·
I've never had that kind of issue. Maybe something like the KMC K1 (in appropriate width) would help?

www.kmcchain.com

K1 Wide- KMC

www.kmcchain.com www.kmcchain.com
www.kmcchain.com

K1 Narrow- KMC

www.kmcchain.com www.kmcchain.com
www.supercrossbmx.com

KMC | K1 Kool Narrow Chain - Single Speed 3/32", 110 Links, Silver/Black

A chain designed for BMX but is at home on any single speed bike needing a chain built to last. The heavy duty structure offers reinforced tensile strength Mushroomed riveting provides high pin power Features an anti-drop design Links (links): 112 Chain Connection Type: Single Use Master Link...
www.supercrossbmx.com www.supercrossbmx.com

I've run them before with good luck (as far as durability goes)
 
#5 ·
#7 ·
Like Kustomz, I too use a straight edge to set up the spacing of the rear cog to make sure it's right in line with the chainring.

I also use a narrow wide chainring mainly because I have an assortment of sizes, of course they are superior at holding chain on.. Aaand, I don't run my chain very tight. With a narrow wide chainring, and a bit of slackness the chain can find it's way right onto the teeth and has never derailed.

I think perfectly aligned gears, slightly loose multispeed chain on a N/W ring are the best kit.


DT
 
#8 ·
bae984 said:
I’ve had occasional chain derailment issues on my Pipedream Moxie in a specific instance for the last year+: higher lean angle, big power accelerations. I swapped from 11s to 9s chain hoping the wider plates and lower articulation would help (and it has) but I’ve still had it happen in that edge case once or twice. Chain tension is correct.

I’ve played with the bike lately and have narrowed it down to the plate-yoke chainstay design. It allows a surprising amount of lateral flex in that ‘leaned over, big mash’ situation. That flex is nice in chunky corners, but losing a chain really sucks. I’m not really interested in a derailleur style tensioner yet, but that may be the fix (outside of a frame swap).

My question is: would a dedicated SS chain be less or more apt to derail in the event of chainstay flex? It seems like a shifty chain might articulate better to accommodate misalignment, but it also has chamfers to encourage a jump.
Click to expand...

How is your rear wheel affixed to this frame?
 
#10 ·
If multi-speed chains are designed to have more lateral movement to compensate for poor chainline, wouldn't this work in your favor on a singlespeed? If they are meant to be misaligned, then derailling easily shouldn't also be true.

I still measure chainline with calipers and believe that you should try to be within a millimeter between cog and ring. But when it comes to chains making a difference, I don't see it.

In the case of the OP, I'd check my chainline. If that looks right then I'd consider a narrow-wide cog.
 
Discussion starter · #11 ·
mikesee said:
How is your rear wheel affixed to this frame?
Click to expand...
Thru-axle into sliding dropouts. Tire centered in yoke. (Wheel dish is correct. Rebuilt by somebody you know after I blew a rim.)

Shinkers said:
If multi-speed chains are designed to have more lateral movement to compensate for poor chainline, wouldn't this work in your favor on a singlespeed? If they are meant to be misaligned, then derailling easily shouldn't also be true.

I still measure chainline with calipers and believe that you should try to be within a millimeter between cog and ring. But when it comes to chains making a difference, I don't see it.

In the case of the OP, I'd check my chainline. If that looks right then I'd consider a narrow-wide cog.
Click to expand...
That’s been my logic on multi-speed chains. I’m using a NW chainring. My theory is I’m pulling the cog out of alignment in higher powered corners, because it feels like it walks off the cog, not the chainring. I’ll pull a straightedge on it today and maybe cheat the cog inbd a mm to help. It’s become much less common since going 8sp, but I’ve still done it. Sucks in a race.
 
#12 ·
bae984 said:
Thru-axle into sliding dropouts. Tire centered in yoke. (Wheel dish is correct. Rebuilt by somebody you know after I blew a rim.)



That’s been my logic on multi-speed chains. I’m using a NW chainring. My theory is I’m pulling the cog out of alignment in higher powered corners, because it feels like it walks off the cog, not the chainring. I’ll pull a straightedge on it today and maybe cheat the cog inbd a mm to help. It’s become much less common since going 8sp, but I’ve still done it. Sucks in a race.
Click to expand...
Multi speed chains will run quieter/ smoother if chainline is off, but with 0 +/-1 mm chainline the less lateral flex of a true singlespeed chain will aid in chain retention. With a stiff chain and out of line chainline you will get a lot of noise/ vibration
 
#13 ·
I've always measured my chainline with a small ruler. it sounds complex but it's not.

1/2 the OD of your seat tube + the distance from your seat tube to the chainring center = chainline

1/2 the length of your axle – chainline = the target distance from the end of your axle to your rear cog.
it takes ten seconds and gets your chainline within 1mm of perfect ever time.

If you're measured chainline is 52mm, and your axle is 148,

148/2 - 52
74 - 52 = 22

In this case, shuffling spacers on your freehub until the cog teeth are 22mm from the end of the axle should get an effectively perfect chainline without eyeballing it or sourcing long straight edges that might not be so straight.
 
#14 ·
mack_turtle said:
I've always measured my chainline with a small ruler. it sounds complex but it's not.

1/2 the OD of your seat tube + the distance from your seat tube to the chainring center = chainline

1/2 the length of your axle – chainline = the target distance from the end of your axle to your rear cog.
it takes ten seconds and gets your chainline within 1mm of perfect ever time.

If you're measured chainline is 52mm, and your axle is 148,

148/2 - 52
74 - 52 = 22

In this case, shuffling spacers on your freehub until the cog teeth are 22mm from the end of the axle should get an effectively perfect chainline without eyeballing it or sourcing long straight edges that might not be so straight.
Click to expand...
This is the method I have used for many years too. Works like a charm.
 
#16 ·
kustomz said:
I used to think my stuff was aligned, but since I had popping and a few drops I finally did something about it. I purchase a 4ft piece of cold rolled 1" wide steel to use as a straightedge. It was way off, so I shimmed things around and thing is reliable now.
Click to expand...
What do you use as your datum/reference with the straight edge? How do you know the straight edge is straight? does the seat stay interfere?
 
#18 ·
mack_turtle said:
I've always measured my chainline with a small ruler. it sounds complex but it's not.

1/2 the OD of your seat tube + the distance from your seat tube to the chainring center = chainline

1/2 the length of your axle – chainline = the target distance from the end of your axle to your rear cog.
it takes ten seconds and gets your chainline within 1mm of perfect ever time.

If you're measured chainline is 52mm, and your axle is 148,

148/2 - 52
74 - 52 = 22

In this case, shuffling spacers on your freehub until the cog teeth are 22mm from the end of the axle should get an effectively perfect chainline without eyeballing it or sourcing long straight edges that might not be so straight.
Click to expand...
This is the way.

With Surly's spacer kit and their offset cogs, I've almost always been able to get my chainline within 1mm.
 
#19 ·
bae984 said:
That’s been my logic on multi-speed chains. I’m using a NW chainring. My theory is I’m pulling the cog out of alignment in higher powered corners, because it feels like it walks off the cog, not the chainring. I’ll pull a straightedge on it today and maybe cheat the cog inbd a mm to help. It’s become much less common since going 8sp, but I’ve still done it. Sucks in a race.
Click to expand...
There are NW cogs which is what I was referring to. That may add an additional layer of security to keeping the chain on.
 
Discussion starter · #20 · (Edited)
Shinkers said:
There are NW cogs which is what I was referring to. That may add an additional layer of security to keeping the chain on.
Click to expand...
Ah, right. I see absolute black has some. Might be the move. I’ve ridden SS for more than a decade and three frames and never had chain retention issues (and never broke out straightedges or micrometers) until this plate yoke frame.
 
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