Chain length for 1x10 hardtail?

[Matthew]

Curious to know how those here on the forum determine chain length on their 1x hardtails. I have a 34 tooth ring up front, 11-36 rear cassette. I used the same method as I do my road bikes: small/small combo and pull the chain so there is a little tension on the rear derailleur and attach there. My issue is when in the largest rear cog and I pedal backwards the chain wants to drop down a cog or two. Is this simply a chainline issue? Chain is angled a fair amount, but figured this is fairly normal for a 1x set up. In this combo the rear derailleur is pulled forward slightly past straight up and down, if that makes sense. How do you guys determine length? Cranks are XT, and the chain ring is a Race Face narrow wide. Thanks!!

[Matthew]

I have noticed some MTB'S that seem to have their rear derailleur screaming for mercy they are pulled so far forward when in the the largest rear cog. Mine is not like that at all. Have adjusted the B screw, and shifting is good. Just have that issue when pedaling backward in the largest cog. As far as B screw goes, you want it adjusted so the top pulley is relatively close to the cassette correct? Believe I have all screws adjusted properly as the shifting is good.

[.RJ]

Try shifting the chainring to the inside of the chainring mount on the crank arms, if you can, but this will happen with Shimano 1x setups sometimes. A worn chain will exaggerate it.

Sram 1x RD's are a little more tolerant of big cross-chaining.

[Matthew]

Thanks, RJ. The chainring is on the inside of the arms. It is a 2x crankset. To be honest I don't know if this set up did this with my old chain or smaller 11-34 cassette. (Chain wanting to drop down when in the largest cog). On the next smallest cog it rotates backward without issue. How do you determine your chain length? Seems like the large cog, large ring up front is the most used method when searching online. Just wonder if it's the same for a 1x?

[christian]

For a non-clutch derailed MTB, I have found that maximum tension helps keep the chain on, so in that case I would do front-big-through-the-derailleur with max tension but not overextended. That way you'd still have the most possible tension in front-small.

I would not be happy with a fully vertical cage in my biggest gear.

[stien]

I have a native 1x SRAM mtb setup and have seen it drop a few cogs while back pedaling in the biggest (42t). Don't do that!

In practice it hasn't been an issue.

[nash]

Derailer hanger may be slightly tweaked. Not enough to affect shifting, but enough to make it do that.

[Matthew]

Derailleur is a clutch style. Rear der., chain, and cassette all brand new. Hanger is straight.

[.RJ]

Hangar wont normally impact that, would show itself elsewhere in the cassette I think.

Is this only on the workstand or out on the trail? It could be a non-issue while out riding.

[Matthew]

Just on the stand right now. Just installed today.

[lexlion]

Thanks, RJ. The chainring is on the inside of the arms. It is a 2x crankset. To be honest I don't know if this set up did this with my old chain or smaller 11-34 cassette. (Chain wanting to drop down when in the largest cog). On the next smallest cog it rotates backward without issue. How do you determine your chain length? Seems like the large cog, large ring up front is the most used method when searching online. Just wonder if it's the same for a 1x?

Sram recommends Chainring+largest cog+4 links when setting chain length.

[TEMPLE]

I was told by a mechanic that it was a common characteristic of Shimano 1x systems. He didn't know why, exactly, but speculated about chainline. My Specialized Enduro has this characteristic, but it's not a problem on the trail unless I spastically decide to pedal a full revolution backwards. If I am just ratcheting like a normal rider, it's fine.

FYI, my bike has full suspension, XT, Shadow Plus rear derailleur. I followed the install instructions exactly (i.e., drain the shock, bottom out the bike, size the chain). The derailleur isn't pulled particularly tight in the biggest cog, but that's before any travel is being used in the suspension system.

Not a satisfying answer, but just wanted to drop my 2 cents/personal experience into the mix.

[Tony]

I have noticed some MTB'S that seem to have their rear derailleur screaming for mercy they are pulled so far forward when in the the largest rear cog. Mine is not like that at all. Have adjusted the B screw, and shifting is good. Just have that issue when pedaling backward in the largest cog. As far as B screw goes, you want it adjusted so the top pulley is relatively close to the cassette correct? Believe I have all screws adjusted properly as the shifting is good.

Chainring spacers will help get the chain line correct. It did for my 1x, can pedal backwards in my largest (42) cog
http://www.jensonusa.com/Chainring-Bolts/Wheels-MFG-Alloy-Chainring-Spacer-Bag20?cs=Silver

Also, use a Goatlink and you will not need to touch your B screw. Shifting will also improve!
http://www.jensonusa.com/Wolf-Tooth-Goatlink-10Speed

[arthurlo]

There are reports that using a KMC or SRAM chain instead of the Shimano chain helps alleviate the issue of the chain dropping from the largest cog when backpedaling.

It is a common issue with Shimano 1x11 systems that don't seem to be as prevalent with the SRAM system. This issue can also be made worse with a 26" bike (shorter distance between crank and cogs leads to a greater deflection angle).

However, this is something that is only an issue in the bike stand and does not really happen on the trail.

[ColonelJLloyd]

How about consulting the tech doc for the actual derailleur you are using?

[.RJ]

How about consulting the tech doc for the actual derailleur you are using?

It wont say anything about 1x10 setup :)

[ColonelJLloyd]

It wont say anything about 1x10 setup :)

And you know which RD the OP is using? Why that info hasn't been stated I don't understand. Furthermore, I don't see what difference one extra cog makes regarding chain length. 36 minus 11 equals 25 teeth total no matter how many cogs are in between the smallest and largest.

If it's a Shimano clutch RD I think they recommend chainring to largest cog plus 2 links.

[Fatty]

2x front cranks may benefit from a spacer or washer to push the ring in a bit and give you a better chainline. Very common washer found at any decent bike shop. Shimano chains are directional, run with the stamped letters on the chain facing out. As for length, Big - Big, and add two links always worked for me. Dually or hardtail.

[.RJ]

And you know which RD the OP is using?

He said XT 10-speed.

[RudAwkning]

If you have any BB spacers, try moving one from the drive side to the non-drive side, just to see if it appears to be a chainline issue.

[Erik_A]

I pull the chain around the largest cog in the rear and the front chainring, break the chain with a 1/2 to 1 link overlap, then add a quick-link. Without a front derailleur, I have found that the shortest possible chain works the best for keeping it from dropping off the front chainring in the bumpy stuff.

[NHAero]

I just did this on my re-purposed Litespeed Unicoi 26er. 1x10 with 11-40 Sunrace cassette and XT8000 RD. SRAM 1071 chain. Seems to work fine.

I pull the chain around the largest cog in the rear and the front chainring, break the chain with a 1/2 to 1 link overlap, then add a quick-link. Without a front derailleur, I have found that the shortest possible chain works the best for keeping it from dropping off the front chainring in the bumpy stuff.

[Matthew]

Colonel. relax man. I said it was an XT clutch derailleur. Maybe I should have stated a GS model or medium cage. Either way, I thought I would check here first as many folks here have vast knowledge of this type of thing. The manual that came with the derailleur is pointless. States nothing about chain length etc. Says to take it to my local professional for install. And I doubt Shimano has any info about which chain length for a 1x10 set up in their tech docs. For those that have offered tips/links I appreciate it. I have learned this may be an issue for this type of set up. I can live with one cog doing this as the shifting is spot on and I will only use this cog to climb the steeper stuff. And when I get a chance to ride it on the trails I shouldn't be pealing backwards anyway!

[Erik_A]

SRAM PC-1031 chains are my current favorite, cheap, and easy to break with a tool. Shifts very well, and long lasting.

http://www.jensonusa.com/SRAM-PC-1031-10-Speed-Chain

[ColonelJLloyd]

I said it was an XT clutch derailleur.

I read all of your posts numerous times. I read about the crank being XT, but could not find the which model RD. I've been known to not see things in front of my face from time to time, though.

The XT8000 tech doc says chainring to largest cog then add two links as I posted. I use this derailleur on my hardtail and this is how I set it up and chain length is good. For edification, chain length for 1x10 or 1x11 is the same for a given chainring and cassette combination.