Need Help assessing issue with chainline on Salsa Timberjack

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Need Help assessing issue with chainline on Salsa Timberjack
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flag Burningbird
FL
Posted: Dec 12, 2016 at 16:42 Quote
I am about to pull the trigger on a Salsa Timberjack and was hoping to get a little input from someone with more knowledge about these things. The Salsa dealer I am working with had an issue with the chainline when they built it up. Sounds like things are fixed but I am a little worried about throwing money at a new model that might have inherent issues. I have copied portions of our email conversation below. Any insight will be greatly appreciated.

" we got the XL Timberjack...and we feel there is a small issue...bad chainline. While it is normal for single ring drivetrains to have issues backpedaling in the largest cog, this bike (and the Lrg we got at the same time) has major issues backpedaling in the top 3 cogs, and even sounds/feels bad pedaling FORWARD in the largest cog. The chainring needs to move towards the centerline of the bike"

follow up email:

"We moved a spacer from the driveside to the non-drive side of the frame (which moved the chainring 2.5mm closer to the frame), that put the chainring teeth 49-50mm from centerline of bike (There is some dis-agreement as to what the best chainline is, SRAM says 52mm is fine for Boost, but others (like One-Up and Wolftooth) think 49mm is better-and I agree with them). That alone did not entirely fix it...so I looked at the distance from the chainring to the cassette, because the shorter the distance, the harsher the angle.

Measuring other 1x11 bike on the floor, many had 50-52mm chainlines...BUT the chainstays were longer, reducing the angle of the chain in the larger cogs. SO, we used the Salsa adjustable dropouts to swing the wheel back ~1/4". Much better. Now the chain (mostly) stays on for multiple backpedal revolutions in all but the largest cog (like many of our floor bikes).

I also tested how the drivetrain worked with a Shimano XT 11-42 cassette instead of the SunRace 11-42. It still did not like backpedaling in the largest cog, and was only a little smoother backpedaling in the second.

We did not have any thin chainring spacers to move the chainring towards the frame a little further, and I don't think its necessary, but its possible to move the ring another 1-2mm inwards later if needed.

I had (another) talk with Seth at Salsa on Friday with my findings and they approve those changes."
flag zsandstrom
O+
Posted: Dec 14, 2016 at 7:51 Quote
Honestly, that sounds like a solid story. If you're skittish about it, you can do as writer of the follow-up email recommended and swap the remaining 2.5mm BB spacer for a 1mm or just remove it altogether. The trick with the chainline on super-short chainstays with boost spacing is (as your post mentions) is to find a happy medium and make the compromise. Boost is great for handling and stiffness, but damn if it isn't a PITA for finding cost effective hubs and drivetrain work.

People talk a lot about spacing and centerline and angles, and it can be easy to get lost in the phrases and numbers. However, in my experience, I've been able to "fix" or "align" the chainline just by spacing the front chainring to be in the middle of the cassette (the 21t cog on your sunrace 11-42 11sp). Every so often there is benefit to 1mm to either side, but it usually negligible.
flag Burningbird
FL
Posted: Dec 14, 2016 at 17:46 Quote
zsandstrom wrote:
Honestly, that sounds like a solid story. If you're skittish about it, you can do as writer of the follow-up email recommended and swap the remaining 2.5mm BB spacer for a 1mm or just remove it altogether. The trick with the chainline on super-short chainstays with boost spacing is (as your post mentions) is to find a happy medium and make the compromise. Boost is great for handling and stiffness, but damn if it isn't a PITA for finding cost effective hubs and drivetrain work.

People talk a lot about spacing and centerline and angles, and it can be easy to get lost in the phrases and numbers. However, in my experience, I've been able to "fix" or "align" the chainline just by spacing the front chainring to be in the middle of the cassette (the 21t cog on your sunrace 11-42 11sp). Every so often there is benefit to 1mm to either side, but it usually negligible.

Thank you for the response! I am purchasing through a reputable shop so I figured it was on the up and up but I feel better getting a second opinion. If I run into any issues, I will update this thread
flag Mrweatherbee
Posted: May 4, 2017 at 1:43 Quote
I just got a LG Timberjack 27.5+ yesterday. Shop pointed out the same issue with the chain line to me but indicated I could get it fixed later if it bothers me. I rode it today... yep, it bothers me. Noise and weird when on the large cog. Backpedaling is definitely a problem. On the big cog, backpedaling not only downshifts but actually throws the chain.

Will switchtheu
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