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How to match Q factor with Rohloff chainline measurement?
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SconnieRoadie
Dec 28, 2012, 11:33:48 AM12/28/12
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Trying to figure out what BB spindle length to use with a White Ind Eno SS crank and a Rohloff hub.
Hub has "54 mm chainline".
Thanks for any help!
Sconnie
Hub has "54 mm chainline".
Thanks for any help!
Sconnie
Peter Howard
Dec 28, 2012, 6:06:20 PM12/28/12
to
Don't have White crank but I do have a Rohloff hub and some experience in
accomodating the 54mm Rohloff chainline.
Looking up the White Industries website, they say that their Eno SS crank
gives a 47.5mm chainline on a 113mm BB and a 51.5mm chainline on a 121mm BB.
Thats on their own JIS square taper symmetrical BB. A bit of arithmetic
gives a 54mm chainline on a 126mm BB which White don't appear to make. If
you can stand the money, Phil Wood does a JIS square taper cartridges in
125mm symmetrical spindle length. Phil BB mounting rings allow 2.5mm
chainline adjustment either side of nominal center so you could be spot-on
with minimal adjustment. You'd need the Phil proprietary BB tool also.
Phil cartridge and cups come in at an eye-watering $178.50 plus $15 for the
tool. Fine if you want an endlessly rebuildable system that you can leave in
your will.
There's a widely advertised $129 SKF cartridge in 126mm.
Around $25 for Shimano UN55 cartridge in 127mm, a trivial difference.
PH
"SconnieRoadie" <sconni...@gmail.com> wrote in message
news:6e001e0e-11c3-4584...@googlegroups.com...
accomodating the 54mm Rohloff chainline.
Looking up the White Industries website, they say that their Eno SS crank
gives a 47.5mm chainline on a 113mm BB and a 51.5mm chainline on a 121mm BB.
Thats on their own JIS square taper symmetrical BB. A bit of arithmetic
gives a 54mm chainline on a 126mm BB which White don't appear to make. If
you can stand the money, Phil Wood does a JIS square taper cartridges in
125mm symmetrical spindle length. Phil BB mounting rings allow 2.5mm
chainline adjustment either side of nominal center so you could be spot-on
with minimal adjustment. You'd need the Phil proprietary BB tool also.
Phil cartridge and cups come in at an eye-watering $178.50 plus $15 for the
tool. Fine if you want an endlessly rebuildable system that you can leave in
your will.
There's a widely advertised $129 SKF cartridge in 126mm.
Around $25 for Shimano UN55 cartridge in 127mm, a trivial difference.
PH
"SconnieRoadie" <sconni...@gmail.com> wrote in message
news:6e001e0e-11c3-4584...@googlegroups.com...
datakoll
Dec 29, 2012, 8:42:06 AM12/29/12
to
you could ask Gary Sokolick
Andre Jute
Jan 2, 2013, 6:24:55 PM1/2/13
to
On Dec 28 2012, 4:33 pm, SconnieRoadie <sconnieroa...@gmail.com>
wrote:
For the longevity of your chain, chainring and to a lesser extent the
Rohloff cog, a Rohloff chainline is critical to within 1mm. But that's
easy to achieve.
White gives us two starting points from which to to calculate the BB
axle length for an ENO crank; see http://www.whiteind.com/images/ENO_CHAIN_RING_CLEARANCE_GUIDE.pdf
As a first approximation, assume symmetrical mounting, i.e. the BB
axle will stick out the same length both sides:
113mm BB, 47.5mm ENO chain line. Rohloff 54mm wanted. 54 - 47.5 is
6.5mm for one side, so the BB axle you want for a Rohloff chain line
with ENO cranks is (2x6.5) + 113mm = 126mm.
Let's check it with the other specification White gives in the same
document:
121mm BB, 51.5mm ENO chain line. Rohloff 54mm wanted. 54 - 51.5 is
2.5mm for one side, so the BB axle you want for a Rohloff chain line
with ENO cranks is (2x2.5) + 121mm = 126mm.
Gee, it's the same result!
I like the Kinex bottom brackets from Czechoslovakia, which are cheap
by the standards of boutique rip-offs but long-lasting. But a Kinex
would probably cost more than it is worth to ship to you.
I currently have a Shimano UN55 fitted but that's overkill unless
you're a very heavy user (it was the only square taper BB offered in
the right size when I was shopping, in fact the only right size, take
it or leave it). CRC has the UN55 in 127mm, which is near enough for
what you want, and offers free shipping. See
http://www.chainreactioncycles.com/Models.aspx?ModelID=71369
Okay, this is precise enough within half a mm of your 54mm chainline
target. But you can hit the 54mm spot on. How? You have to lose 0.5mm
on the drive side, and you do this by fitting a spacer behind the
lockring on the non-drive side to pull the axle to an asymmetrical
position. The spacer should be 0.5mm thick. You can buy axle spacers
but if you have a cassette spacer or other spacer of the right
diameter and thickness, that will do well.
Bingo, you have a 54mm chainline, spot on.
For the Rohloff I like the KMC X8 chains, which last me about 4500km
(I'm very heavy on chains -- this is double what I get on Shimano and
SRAM chains; others do better on the X8, up to and including
incredible mileages like 10K and up). However, this is a derailleur
chain, and some of the top German bicycle makers fit the Z8 to Rohloff-
hubbed bikes as a cheaper alternative made for single speed gear
trains. The choice is up to you, but I find I can buy the X8 cheaper,
delivered to my door, than the Z8, and the X8 is definitely a superior
chain.
If you have a Rohloff, the friendliest and best informed place to hang
out is the Rohloff sub-board of the Thorn owners' site at
http://www.thorncycles.co.uk/forums/index.php?board=25.0
Anything you want to know, ask.
Andre Jute
wrote:
Rohloff cog, a Rohloff chainline is critical to within 1mm. But that's
easy to achieve.
White gives us two starting points from which to to calculate the BB
axle length for an ENO crank; see http://www.whiteind.com/images/ENO_CHAIN_RING_CLEARANCE_GUIDE.pdf
As a first approximation, assume symmetrical mounting, i.e. the BB
axle will stick out the same length both sides:
113mm BB, 47.5mm ENO chain line. Rohloff 54mm wanted. 54 - 47.5 is
6.5mm for one side, so the BB axle you want for a Rohloff chain line
with ENO cranks is (2x6.5) + 113mm = 126mm.
Let's check it with the other specification White gives in the same
document:
121mm BB, 51.5mm ENO chain line. Rohloff 54mm wanted. 54 - 51.5 is
2.5mm for one side, so the BB axle you want for a Rohloff chain line
with ENO cranks is (2x2.5) + 121mm = 126mm.
Gee, it's the same result!
I like the Kinex bottom brackets from Czechoslovakia, which are cheap
by the standards of boutique rip-offs but long-lasting. But a Kinex
would probably cost more than it is worth to ship to you.
I currently have a Shimano UN55 fitted but that's overkill unless
you're a very heavy user (it was the only square taper BB offered in
the right size when I was shopping, in fact the only right size, take
it or leave it). CRC has the UN55 in 127mm, which is near enough for
what you want, and offers free shipping. See
http://www.chainreactioncycles.com/Models.aspx?ModelID=71369
Okay, this is precise enough within half a mm of your 54mm chainline
target. But you can hit the 54mm spot on. How? You have to lose 0.5mm
on the drive side, and you do this by fitting a spacer behind the
lockring on the non-drive side to pull the axle to an asymmetrical
position. The spacer should be 0.5mm thick. You can buy axle spacers
but if you have a cassette spacer or other spacer of the right
diameter and thickness, that will do well.
Bingo, you have a 54mm chainline, spot on.
For the Rohloff I like the KMC X8 chains, which last me about 4500km
(I'm very heavy on chains -- this is double what I get on Shimano and
SRAM chains; others do better on the X8, up to and including
incredible mileages like 10K and up). However, this is a derailleur
chain, and some of the top German bicycle makers fit the Z8 to Rohloff-
hubbed bikes as a cheaper alternative made for single speed gear
trains. The choice is up to you, but I find I can buy the X8 cheaper,
delivered to my door, than the Z8, and the X8 is definitely a superior
chain.
If you have a Rohloff, the friendliest and best informed place to hang
out is the Rohloff sub-board of the Thorn owners' site at
http://www.thorncycles.co.uk/forums/index.php?board=25.0
Anything you want to know, ask.
Andre Jute
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