Gravel Bike 1x Drivetrain Question - Chain length/Noise

I have a 1x12 SRAM setup on my XC bike and I really like it. So, I put my skepticism aside and upgraded to a 1x11 system on my gravel bike.

Here is how I built it:

  • Shimano 105 right shifter (11s)
  • Wolftooth Tanpan
  • Shimano SLX-GS derailleur
  • Shimano 11-40 cassette
  • Wolftooth PowerTrac Elliptical 40T 110BCD chainring
  • Box 11 Speed Chain

I added four (4) links (3+quick link) to the chain after wrapping it around the large cog and chainring. However, the chain angle looks pretty extreme to me. According to Shimano’s site the derailleur can handle up to a 46T chainring w/ a 1x setup. So perhaps I am overthinking things…?

Here are some photos:

Small cog chain angle (please not I am not referring to chain line - how the chain tracks from the chainring to the cassette. Rather I am referring to how straight the chain is coming off of the small cog towards the derailleur’s jockey [upper] pulley).

The derailleur cage angle is pretty far forward (might be easier to see in the top photo)… Is this normal? Am I overthinking things? I just do not want my drivetrain to blowup on the first big hill…

My concern might be a little more heightened because the drivetrain is pretty noisy. All the components are new, so perhaps it just needs to be broken in a bit?

That looks like nearly not enough chain length to me.

  • I am no expert, but the middle pic (on the small cog) should look very different.
  • I size based on this small cog and set the length so the derailleur has just a bit of clearance between the lowest chain and the lead pulley on the RD.

This is the shortest I would setup a chain for use. (stock photo, but close to what I do):

  • image

It’s kind of hard to tell from your photo angles, but have you properly set the derailleur’s B-screw distance for the big cog according to the derailleur specs? Kind of looks like the upper pulley might be further from the cassette than ideal, and that would add tension and increase the pulley cage angle.


B-Tension is also important, but I would correct the chain length issue first.

Good point @mcneese.chad, I missed that angle on the smallest cog. That does indeed look too short there (plus b-screw distance appears way off in smallest cog picture too of course - making it worse).

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That is more what I was expecting mine to look like. The chain I bought had 116 links. I only took 5 off to get to my current chain length… According to Park’s chain length equation:

L = 2xC + (F/4 + R/4 + 1)

L = Chain length in inches. Round the final result to closest whole inch figure.
C = Chain stay length in inches, measure to closest 1/8".
F= Number of teeth on largest front chainring.
R= Number of teeth on largest rear cog.

My chain should be 53" long (16" chain stay, 40T chainring, 40T Cog) My chain is 53" long… Obviously this could be for a 2x or 3x setup though. I am so confused

The math may be right, but what I see as results on your bike… says it’s wrong. I can’t offer a reason based on the calculation, because I never calculate and only size chains live on the bike.

The effective use on the bike is what matters, and yours is not right, despite the calculations. The middle pic above is about what you should see in the upper middle of the cassette (24-26t cogs?).

I agree with you @mcneese.chad that it doesn’t look right. Now I need to figure out how long of a chain is actually correct…

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I would start with the B tension. It looks like the upper jockey wheel is at least an inch from the cogs in both pictures. That might give you quite a bit more slack in the chain. It’s an easy adjustment to make without needing to add in extra links.


Yup chain too short

@dbf @Notso I did have the B-screw backed off too much. Once I got it adjusted the jockey pulley chain angle looks a lot better.

Small cog after adjustment

Mid-cassette after adjustment

Large cog after adjustment

@mcneese.chad What are thoughts now after adjusting the B-screw on chain length?

The derailleur when in the 40 tooth cog looks less over extended now. Anyone have any photos of their 1x11 gravel setup to compare with?

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That definitely looks better to my eye. How does it look in the smallest cog?

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I would use a chain that is a few links longer. The derailleur arm looks too extended in photo #1. Probably would be OK but if not would be a real disaster. So risk = smallish; impact = hugish.

In the 2nd picture the derailleur looks like it has plenty of room to articulate back and take up chain slack. So you’d be ok to add a few links.

I noticed a little more noise from my narrow-wide chainring. Maybe it’s just the nature of a narrow-wide gear interacting with the chain?


Much better with the B-tension. But I do think 1 or maybe 2 more links would be the icing on the cake.
That stretch on the large cog isn’t horrible now, but I think it’s about on the edge.

I would potentially run that if you had no other option, but I think at least one more might be the right choice.

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Agree with Chad… Still add a link or two

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That is a good point. I’ve never used Box chains before. Perhaps they’re just more noisy than SRAM, which are currently the only 1x chains I’ve used.

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Consensus seems solidly in the camp of adding 1-2 more links. I’ll make the adjustment and report back. Thank you everyone for your input. I really appreciate it :slightly_smiling_face::slightly_smiling_face::slightly_smiling_face:

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I added the extra few links that I had removed bringing the chain length to a total of 116. I figured if it was too long I could remove one or two.

Looks a lot better now.

Took my son to the beach the other day and put the new drivetrain to the test with a nice 43km RT jaunt. She rides real nice besides a sticky clutch making the top three gears hard to use…

That looks really good now.

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Thank you for all your help

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