1x11 Front Ring alignment

mtb101

Likes Bikes and Dirt
A new Giant xtc 29er, 1x11 xt with 11-46 and back pedaling on the 46 causes chain to drop down cassette, now mechanic at shop says its due to large size cassette. New bike so hasn't been ridden yet.

He doesn't know I've converted quite a few 1x11s and don't have chain drop issue.

Looking at press fit there's a spacer on the drive side, which would mean the front ring could go in more.

I don't like changing factory setup but that looks like the reason. what you guys reckon?
 

DMan

alid sinistra oliva
I'd do it. From what I understand it doesn't matter so much which side the spacer is on as long as it's there. So put it on the otherside if that improves your "chainline". I did that with my Nukeproof scout to get a better "chainline" and there were no issues.
 

ctguru

Likes Bikes and Dirt
I'd ride it first

My 1x11's don't do it, but my mates does

I'd see if it is an issue before playing with it
 

moorey

serial meme abuser
All my Shimano (5) 1x11's do it. My sons X1 doesn't, unless back-pedalled fast.

Mine only do it from big cog, and only after a full backpedal, and it's never concerned me. I've played with spacers, no change.
That 11-46 Shimano is a horrible looking thing, and too big a jump up in my limited experience. I'll be sticking with 11-42.
 

Boom King

downloaded a pic of moorey's bruised arse
All my Shimano (5) 1x11's do it. My sons X1 doesn't, unless back-pedalled fast.

Mine only do it from big cog, and only after a full backpedal, and it's never concerned me. I've played with spacers, no change.
That 11-46 Shimano is a horrible looking thing, and too big a jump up in my limited experience. I'll be sticking with 11-42.
You know what they're doing don't you?
images.jpeg
 

The Duckmeister

Has stumpy thumbs, Speciaized are so weird
Generally speaking the chainring is in the same alignment as the middle ring of a 3x. 11-sp. is wider than 8/9/10-sp, with the extra sprocket located inboard, meaning there is greater chain deflection to get to the low gear. Chains & sprockets aren't designed with going backwards in mind, and with worse alignment (or greater misalignment if you will), are more likely to misbehave when asked to go the wrong way. Short version is don't backpedal in low gear!
 

mtb101

Likes Bikes and Dirt
thanks for replies, I'm going to see if Giant have a tech doc on whether the spacer should be on the drive side, I've set up about 8 1x11s and the back pedal is a good sign of the chain line being ok.

as you guys know on a steep mother of a climb, we need to sometimes pedal, roll and occasionally back pedal to avoid rock, pedal strike and pedal again, nothing worse than the chain grinding down the cassette under load and adding another thing to focus on when you're just picking a line through steep stuff.
 

Daniel Hale

She fid, he fid, I fidn't
boost or non-boost -i took out the big spacer ring & got a much thinner one -[with no spacer cranks just scraped the boost frame] NB on most there is supposed to be a spacer on the drive side. problem with press fit is the spacer prob helps keep moisture out of the bb bearings.. i wish some bike manufacturer had the balls to bring back square taper BB's & cranks
 

schred

Likes Bikes and Dirt
Yeah on both bikes that did it (Giants), spacer was on drive side. On 2nd bike, it would do it with the 32/46 combo off the showroom floor, but now with 34/42 it doesn't do it, but it's not exactly a happy chainline just because it isn't doing it. In fact chain is running nice and straight on 3rd sprocket up from the bottom (11sp) so nowhere near the middle of the cluster if that's the aim.
 

ozzybmx

Níl aon tóin tinn mar do thóin tinn féin
All my Shimano (5) 1x11's do it. My sons X1 doesn't, unless back-pedalled fast.
^^^ This. Seems to be a Shimano thing, happens on the 2 bikes I have with 11spd Shimano... but not on the SRAM that was on one of them before I 'upgraded' to XTR Di2.

Thats an upgrade to something that doesnt work as it should...
 

moorey

serial meme abuser
^^^ This. Seems to be a Shimano thing, happens on the 2 bikes I have with 11spd Shimano... but not on the SRAM that was on one of them before I 'upgraded' to XTR Di2.

Thats an upgrade to something that doesnt work as it should...
Really, who backpedals on the big gear? It's a moot point, really.
 

ozzybmx

Níl aon tóin tinn mar do thóin tinn féin
You dont do steep techy climbs ?

Ok, it usually happens when either sitting on the bike at standstill or wheeling it backwards to move it somewhere.
 

moorey

serial meme abuser
You dont do steep techy climbs ?

Ok, it usually happens when either sitting on the bike at standstill or wheeling it backwards to move it somewhere.
I prefer to pedal forwards on steep climbs.
Don't wheel it backwards in 11th gear?
 

ozzybmx

Níl aon tóin tinn mar do thóin tinn féin
A bit of a half back pedal strike avoidance over rocks is enough to drop it down to cog 10.

Would love to have the hindsight that I may need to do a reverse ;)
 

moorey

serial meme abuser
A bit of a half back pedal strike avoidance over rocks is enough to drop it down to cog 10.

Would love to have the hindsight that I may need to do a reverse ;)
I can't say half a back pedal does it on any of mine. Maybe start a thread about chain alignment. o_O
 
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