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Old 10-20-11, 07:23 AM   #1
saddlesores
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disc hub/standard rim w/v-brakes...off center????

so i got a set of wheels made. i have standard rims as i'm using
v-brakes. disc hubs in case i decide to go that way some day (and
anyway, that's all that were available here). now i'm trying to
adjust the v-brakes. having some trouble, and i notice the wheel is
not centered. left v-stud to rim surface is 2.5cm, right v-stud to
rim surface is 3.0cm.

is this normal? is it due to required dishing because of the disc
mount? am i hopelessly clueless in thinking the rim should be
centered on the axle? or is the wheelbuilder just a dumbass?
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Old 10-20-11, 07:38 AM   #2
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No.
No.
No.
Possibly.
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Old 10-20-11, 07:39 AM   #3
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The rim should be centered over the middle of the axle's OLD, which should result on it being centered in the frame. Don't know what an acceptable tolerance is.
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Old 10-20-11, 07:52 AM   #4
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i ordered a set of wheels using a pair of disc hubs. i told the guy one wheel will use a disc brake, the other
will have a v-brake. what rims he asks? well i said (and this is difficult cause the guy speaks chinese),
the wheel with the v-brake must have a standard rim. the other wheel really doesn't matter since the
disc brake doesn't use it as a braking surface.

yes, there are language difficulties....the hard part is explaining i want a standard rim. (i'd have preferred
one non-disc hub, so one less wheel dished, but noone will sell hubs separately.) i don't care that i will be
using standard rims with disc brakes. the brakes don't care! it won't be as pretty, he says. i don't care.
it's a bike, dammit.

i expect to get a set of standard rims. nope, i get one each. doesn't match. ok, i don't care. i can still
sleep at night. at least he got the right rims on the right wheels. well, he didn't dish the v-wheel correctly.
i'm about 1/2 centimeter offset. v-brakes won't work when the wheel is off that much.

the builder says i didn't ask for the wheels to be centered! WTF! aren't even disc wheels centered? i
wasn't aware i had to ask for built wheels to be centered.
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Old 10-20-11, 07:55 AM   #5
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i checked and rechecked and checked again. total 5mm difference. so would have to be re-dished to
move the rim about 2.5mm to one side.

yes, i checked everything. thought i may have misadjusted something when i moved the fork to a
new frame and remounted everything. nope. just switched the old wheel back in, centers quite
nicely.
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Old 10-20-11, 08:57 AM   #6
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Quote:
Originally Posted by saddlesores View Post
the builder says i didn't ask for the wheels to be centered! WTF! aren't even disc wheels centered? i
wasn't aware i had to ask for built wheels to be centered.
That's a cr@ppy wheel builder. Avoid. That ignorant/nonchalant, who knows what else he might come up with?
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Old 10-20-11, 08:59 AM   #7
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Originally Posted by saddlesores View Post
.. v-brakes won't work when the wheel is off that much.
Well, yes, they do. You can't put any force into the system until both pads contact the rim, so no worries there.
But it'll be ugly, and unless you offset the brake adjustment, one pad might wear faster due to drag.
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Old 10-20-11, 12:20 PM   #8
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no chance of getting the wheel re-dished in this town, that'll have to wait. i doubt chucking a spacer onto
the axle between the hub and dropout would be advisable.

i guess i could follow dabac's advice. deore brake pads have a 3mm spacer behind the pad, 6mm spacer
other side of the arm. switch those around, perhaps add a 1mm washer, should get me close.........

thanks for the responses.
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Old 10-20-11, 12:32 PM   #9
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Flip the wheel over, see if the offset is the other way, by the same amount.

then do a bit of truing and checking with a Dish Stick, till the reference can be flipped
and both sides are the same.

pick up a spoke wrench , and DIY, to make it so.

Last edited by fietsbob; 10-20-11 at 12:46 PM.
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Old 10-20-11, 01:17 PM   #10
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new wheel offsets 2.7/3.4 flipped 3.3/2.8
old wheel offsets 3.1/3.5 flipped 3.2/3.4

the first set for each is with the wheel in the 'correct' forward orientation.
brakes work with the old wheel.

those are the best measurements i can get with the measurin' thingies i have.
but it's 3am and my eyes are tired and chinese lighting sucks....
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Old 10-22-11, 08:04 AM   #11
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i give up. no way to adjust them v-brakes with spacers to a USABLE
configuration. and no point in trying to re-dish the wheel. with the
disc mount offset, the non-disc spokes are getting close to freakin'
vertical already. i'm not even going to look, as i suspect the 'builder'
used the same length spokes on both sides, so getting this here
wheel dished will likely cause the spoke ends to poke through the
rim strip. (and i'm not gonna look) i convinced the dude to take the
front wheel back for a refund. i'm gonna stick with my old deore
hub and cr18 rims.

thank you all for your time.
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Old 10-25-11, 07:46 AM   #12
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.. no point in trying to re-dish the wheel. with the
disc mount offset, the non-disc spokes are getting close to freakin'
vertical already.
Well, if it's a rear wheel, the non-disc AKA drive side spokes will be pretty close to vertical. If it's a front, the non disc spokes should lean more than the disc side spokes.
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Old 10-26-11, 05:26 AM   #13
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doesn't the rear wheel come out stronger with a disc mount? now there is a thingie on each side
of the hub, pushing the flanges towards the center. spokes are closer to equal length (closer than with just a
cassette anyways) and equal tension.

but it makes a huge difference on the front with a narrower hub. adding that disc mount pushes the one flange
way into the center. get a crappy wheelbuilder and you actually wind up with what you wanted in the first place;
a standard hub to use with your v-brakes, only noone wanted to sell one wheel.
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Old 10-26-11, 06:03 AM   #14
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doesn't the rear wheel come out stronger with a disc mount?
No, or not much.
It may come out more long-lived, as it may have less difference in spoke tension. And looser spokes fatiguing and then breaking is a common problem. But it's not a given. I've had some hubs where the NDS flange had been hunched inwards more than the disc mount actually called for, just to ease the tension imbalance.
But if you're talking about strength as resistance to taco-ing, that doesn't change with spoke tension, until the spokes go slack entirely.
For lateral rigidity, the bracing angle is real important, which means that most rear wheels are a lot softer in one direction than the other. A wheel built on a disc hub may be less asymmetric. The sideways strength for the drive side will be the same, and the sideways strength for the brake side may be less.
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Originally Posted by saddlesores View Post
but it makes a huge difference on the front with a narrower hub. adding that disc mount pushes the one flange
way into the center.
Well, sure. A front rim braked will have a 100/100% tension balance, while my last disc braked was 100/66%. Rears tend to do even worse, disc braked or not.
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Old 10-26-11, 07:43 AM   #15
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... only noone wanted to sell one wheel.
With this statement and the one on another thread that your LBS will only sell a chain if you agree to buy shifters and derailleurs, I am starting to think maybe you aren't asking the right questions.
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Old 10-26-11, 10:13 AM   #16
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this is china. we don't do customer service. take it or leave it.

the shop buys groups which include the chain. they don't sell
components separately. buy all or nothing. individual parts gotta
be sourced on line.

builders won't sell a single wheel, as they feel they'll be stuck with an
orphan hub.

it takes a while to get used to the retail culture here. came across one
shop that won't stock popular items because they'll sell out and have to
re-stock. really. that's what the manager told me.
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Old 10-26-11, 10:21 AM   #17
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Dish stick, rim centered the difference is zero, when right.

Brake: Just bend the return spring on one V brake to increase the weak return.
there is a screw on the bottom of each to fine tune return tension
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Old 10-27-11, 11:03 AM   #18
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this is china.
That explains it!
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