Keychain woes?

[badlight]

My keychain did the same thing on a brand new deluxe sprocket. I just kept riding it, it's fine. My sprocket looks a lot less worn than yours though, but I may also just be crazy.

[montymitch]

Is your chain very tight? The aim of a chain (or the threads on a bolt/nut) is to transfer the load from the sprocket to the chain (or the bolt to the nut). You can never expect the components to fit so perfectly that they all take an equal share of the load, so the last tooth will take most, and then the next one a bit less (or the first thread for a bolt/nut). Typically, it is just the first 3 teeth (or threads) that take 80% of the load or more, and the further you move from the load the less it is. So you would expect to always see something like you have there... having said that, it is obviously hard to tell from a video compared to having it in your own hands, but it does look like maybe that is a bit extreme for all brand new parts.

How does it ride? If it seems OK to ride, then please check that the chain tension isnt excessive and try riding it and see if it seems to improve or worsen.

I hope this makes sense and seems reasonable.


G.

The only reason I noticed this in the first place was that I was having a difficult time getting chain tension dialed in. I'm a seasoned rider, I've worked in bike shops, and I've built and maintained my own rides for decades. If I back off the chain tension, I get slap on the chainstay. If the chain is taught, I get the weirdness seen in the video. It's definitely a little notchy feeling when I ride it.
In my experience, the first few teeth should be tight under load, and then slack on the sprocket after that. The thing that is odd about this is that it's tight where the chain comes off of the sprocket and loose in the middle. I imagine the chain will fit a little better after it has stretched a little, but I'm worried that in the mean time it will ravage my sprocket, driver, or both.

[streetStreet]

Do you use tensioner's?

[montymitch]

Do you use tensioner's?

Yep. It's a Sunday 2nd Wave with the built in tensioners. I've never encountered this problem.

[weedbix]

Chain line? what? How could that have anything to do with it? lol maybe im missing something.
Chain line mathematically?

1. Misalignment + tension
2. Yep. Can't trust eyes (unless you are iamhollywood)

[stevefromtexas]

Mine kinda did the same thing make sure your alignment is on point. You will have to ride it for a couple days it should be fine after that mine works good best chain ever made.

[montymitch]

Yeah, I'm not really sold on it yet. My chainline is spot on and a $50 chain that lasts forever is no good if it destroys the rest of my drive train in the process.
As for mathematically calculating my chainline, I'm calling BS. This is a BMX bike. If micrometers are needed for setup, you're doing it wrong.

[stevefromtexas]

Idk what are you running I'm running 28/9 with a tree sprocket I got my chain super tight and it works fine

[stevefromtexas]

I was looking at your video could be your sprocket it's hard to tell make another one spinning your cranks

[weedbix]

Yeah, I'm not really sold on it yet. My chainline is spot on and a $50 chain that lasts forever is no good if it destroys the rest of my drive train in the process.
As for mathematically calculating my chainline, I'm calling BS. This is a BMX bike. If micrometers are needed for setup, you're doing it wrong.

Who said anything about micrometers? How do you know if it's spot on? Sight is a lousy indication, even a battered square edge is better

[Oddity]

We have nearly the same setup save for the sprocket, I have a 28t Tree and mine is the does the same thing as your video shows. Even with the shitty drive line alignment I have(wide tire accommodating frame that barely fits a 28t with loads of spacers) it feels absolutely great riding it, it's probably the smoothest setup I've ever had, no noise, no harsh spots, no random tight spots, or uneven wear on the sprocket. I say you're over thinking this and just ride it, it's a bmx bike afterall.

[weedbix]

A quick blurt for anyone interested who can't work out to do it:

Rear ends are 110 from inside of left dropout to inside of right (overlucknut dimension)

110 / 2 = 55mm

55 - 11.5 (distance from inside of right drop to centre of driver teeth on Ratchet and possibly Antigram) = 43.5

Middle of driver teeth is 43.5mm from centre of drops/BB

----

Say your BB is 75mm wide (you'll have to measure to find out how wide it actually is, range I've seen is from 68 to 80mm)

75 / 2 = 37.5

Say you have a 5mm sprocket with the teeth in the centre of the sprocket

5 / 2 = 2.5mm

43.5 - 37.5 = 6

6 - 2.5mm = 3.5

3.5mm of spacing between BB bearing and that sprocket to align it with driver

[montymitch]

A quick blurt for anyone interested who can't work out to do it:

Rear ends are 110 from inside of left dropout to inside of right (overlucknut dimension)

110 / 2 = 55mm

55 - 11.5 (distance from inside of right drop to centre of driver teeth on Ratchet and possibly Antigram) = 43.5

Middle of driver teeth is 43.5mm from centre of drops/BB

----

Say your BB is 75mm wide (you'll have to measure to find out how wide it actually is, range I've seen is from 68 to 80mm)

75 / 2 = 37.5

Say you have a 5mm sprocket with the teeth in the centre of the sprocket

5 / 2 = 2.5mm

43.5 - 37.5 = 6

6 - 2.5mm = 3.5

3.5mm of spacing between BB bearing and that sprocket to align it with driver

Thanks for that. It seems to me that there are always issues that prevent a perfect chain alignment. Chainstay clearance, BB width vs spindle length issues, and the less than perfect alignment of the whole rear triangle often (not always) make chain line a secondary issue.

As for the bike, I've been riding it and it isn't smoothing out as well as I'd like. The chain is popping every once in a while, which messes with my head since the last time (different bike) my chain made popping noises it broke three hard cranks later and sent me over the bars.

[stevefromtexas]

Elite 9 tooth tree 28 mine works fine

[G]

A quick blurt for anyone interested who can't work out to do it:

Rear ends are 110 from inside of left dropout to inside of right (overlucknut dimension)

110 / 2 = 55mm

55 - 11.5 (distance from inside of right drop to centre of driver teeth on Ratchet and possibly Antigram) = 43.5

Middle of driver teeth is 43.5mm from centre of drops/BB

----

Say your BB is 75mm wide (you'll have to measure to find out how wide it actually is, range I've seen is from 68 to 80mm)

75 / 2 = 37.5

Say you have a 5mm sprocket with the teeth in the centre of the sprocket

5 / 2 = 2.5mm

43.5 - 37.5 = 6

6 - 2.5mm = 3.5

3.5mm of spacing between BB bearing and that sprocket to align it with driver

This is great, but it assumes that the frame is straight and very often they aren't! I would always suggest checking with a straight edge too if at all possible.


G.