fixie chainline adjustment with stack bolt spacers (?)

ant said:

a new fixie of mine has an imperfect chainline, and id like to fix it. so to speak. the rear hub
is an eccentric white ind ENO, and is not respaceable (not that id really want to). the front
crank is an ultegra double, with a ring on the inside position.

as it is, it appears that the ring wants to be a few mm further in. there is chainstay clearance
for this, but i dont think there are any shorter spindle lengths available from shimano. i also
dont want to dish out the big big bucks for an adjustable chainline bb from some other company
(ive seen them somewhere, dont know if they would be appropriate for this application, but
anyway).

somewhere in Sheldon's bike literature i read once about spacing a chainring with stack bolt
spacers to achieve a good chainline.

a) is this my best option?

It's an option, but probably not the best in your case.

Quoted message said:

b) what are the limits of this? (for future reference)

I don't like to go past 3 mm with this.

However, there's something screwy here. The White Industries hub, with a typical sprocket or
singlespeed freewheel gives about a 47 mm chainline in back.

Shimano double cranks with prescribed BBs give a 43.5 mm chainline measured between the rings. This
would normally put the inner ring at 41, outer at 46.

I think you've got the wrong BB for your crank; should be 109.5 but I'm guessing you got the 118.5
BB intended for a triple by mistake.

If not that, my guess is that your frame is bent.

See also sheldonbrown.comchainlineOpen ↗

Sheldon "Straight Ahead" Brown +----------------------------------------------+
| My mind is aglow with whirling, transient | nodes of thought careening through a cosmic | vapor
| of invention! --Mel Brooks |
+----------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone
617-244-9772 FAX 617-244-1041 harriscyclery.comharriscyclery.comOpen ↗ Hard-to-find parts shipped Worldwide
captainbike.comcaptainbike.comOpen ↗ sheldonbrown.comsheldonbrown.comOpen ↗

Sheldon Brown said:

ant said:

a new fixie of mine has an imperfect chainline, and id like to fix it. so to speak. the rear hub
is an eccentric white ind ENO, and is not respaceable (not that id really want to). the front
crank is an ultegra double, with a ring on the inside position.

as it is, it appears that the ring wants to be a few mm further in. there is chainstay clearance
for this, but i dont think there are any shorter spindle lengths available from shimano. i also
dont want to dish out the big big bucks for an adjustable chainline bb from some other company
(ive seen them somewhere, dont know if they would be appropriate for this application, but
anyway).

somewhere in Sheldon's bike literature i read once about spacing a chainring with stack bolt
spacers to achieve a good chainline.

a) is this my best option?

It's an option, but probably not the best in your case.

Quoted message said:

b) what are the limits of this? (for future reference)

I don't like to go past 3 mm with this.

However, there's something screwy here. The White Industries hub, with a typical sprocket or
singlespeed freewheel gives about a 47 mm chainline in back.

Shimano double cranks with prescribed BBs give a 43.5 mm chainline measured between the rings. This
would normally put the inner ring at 41, outer at 46.

I think you've got the wrong BB for your crank; should be 109.5 but I'm guessing you got the 118.5
BB intended for a triple by mistake.

If not that, my guess is that your frame is bent.

See also sheldonbrown.comchainlineOpen ↗

Sheldon "Straight Ahead" Brown +----------------------------------------------+
| My mind is aglow with whirling, transient | nodes of thought careening through a cosmic | vapor
| of invention! --Mel Brooks |
+----------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone
617-244-9772 FAX 617-244-1041 harriscyclery.comharriscyclery.comOpen ↗ Hard-to-find parts shipped Worldwide
captainbike.comcaptainbike.comOpen ↗ sheldonbrown.comsheldonbrown.comOpen ↗

at risk of stating the completely obvious, maybe the hub isn't central in the dropouts. Presumably
the hub is designed to run at 120mm OLN, and also presumably (based on the eccentric, I'm guessing
its in a road frame with vertical dropouts) its actually between dropouts spaced at 126 or 130.

OK, it would be particularly dumb to move the hub in the "wrong" direction with spacer, so I imagine
Sheldon's guess that the BB is the wrong length is the right one. Kinky Cowboy

*Your milage may vary Batteries not included May contain traces of nuts.

KinkyCowboy <[email hidden]> wrote in message

Quoted message said:

at risk of stating the completely obvious, maybe the hub isn't central in the dropouts. Presumably
the hub is designed to run at 120mm OLN, and also presumably (based on the eccentric, I'm guessing
its in a road frame with vertical dropouts) its actually between dropouts spaced at 126 or 130.

frame spacing is 130. but so is the hub. (quite a nice hub, if i do say so myself). the hub is a
cartridge bearing hub with repleaceable machined spacers that bolt to the axle. i have installed the
130mm set.

Quoted message said:

OK, it would be particularly dumb to move the hub in the "wrong" direction with spacer, so I
imagine Sheldon's guess that the BB is the wrong length is the right one. Kinky Cowboy

the spacers are single pieces, machined from stainless. one per side. you cant fiddle with 'em.

Sheldon Brown <[email hidden]> wrote in message

Quoted message said:

However, there's something screwy here. The White Industries hub, with a typical sprocket or
singlespeed freewheel gives about a 47 mm chainline in back.

Shimano double cranks with prescribed BBs give a 43.5 mm chainline measured between the rings.
This would normally put the inner ring at 41, outer at 46.

yeah. i did the calculations using your chainline specs and was delighted (pre-build) to find that
the outer ring would put me almost exactly in line. when i put her together, i just figured i forgot
to carry a digit somewhere.

addition. thats always a tricky one.

Quoted message said:

I think you've got the wrong BB for your crank; should be 109.5 but I'm guessing you got the 118.5
BB intended for a triple by mistake.

hm. i didnt even think of that. the bb i installed was new, and came in a box marked 109.5, but you
never know, i suppose. i didnt actually measure it.

Quoted message said:

If not that, my guess is that your frame is bent.

its a carbon frame. i can just align it with a 2x4, right 😉