spinningmagnets
100 TW
Kinaye Motorsports has put together a 1-hour-20 minute video with a comprehensive start-to-finish hubmotor wheel-lacing and discussion video.
https://www.youtube.com/watch?v=CZ3Ji72-qM4&feature=youtu.be
[youtube]CZ3Ji72-qM4[/youtube]
I am thinking about tackling my first wheel build. I may assemble a Xiongda 2-speed onto a 26-inch rim, or a Bafang BPM, and...it appears the only way to make sure I get the motor I want (BPM 10T) is to buy the unlaced motor with no spokes or rim. Also, I have read many times that when you do get an entire wheel, the spokes and rim quality are sometimes disappointing, so...any money that you saved on a pre-assembled wheel is off-set by paying more for shipping a larger box, and then needing to throw the rim/spokes away.
Offset rim
Often, a front wheel has the spoke-flanges equally spaced from the center, so the spokes from both sides are the same length. Sometimes, a rear wheel has evenly-spaced spoke-flanges, but the width of the 7-speed sprocket-cluster means in order to have the wheel-rim centered (to work properly with a rim-brake)...the rim has to be off-set nearer to the sprockets, so the freewheel side spokes need to be shorter than the disc brake side spokes.
Radial, one-cross, 2-cross lacing pattern
I am told a radial lacing is quite bad, since it doesn't allow the spokes to be able to properly do their job. A large hub in a smaller rim may have no other option (and this is why the 20-inch Magic Pie has cast aluminum spokes).
A smaller hub in a larger rim can have a 2-cross pattern, which apparently works quite well. However, if you are lacing a larger hub to a rim, you may have to settle for a one-cross pattern to avoid the spokes having too much of an angle. (pedal-only bicycles often have a 3-cross pattern, and in rare cases, a 4-cross...I have never seen an electric hubmotor where a 3-cross or more was appropriate due to the resulting extreme nipple angles)
Wheel Rims
Double-wall rims have grown in popularity, but if you are switching a single-wall rim to a double-wall, you may need slightly shorter spokes. Double-walled rims are stronger and have been developed for mountain bikes and downhill bikes. Rims often have their weights listed, and that was originally for builders who wanted to save weight. However, for an electric bike, a rim that is heavier (between two choices) is likely to be stronger.
Here is a pic of the nipple heads on a single-walled rim (pic courtesy of Sheldon Browns website)
View attachment 4
Double-butted spokes
Thinner spokes are able to flex better, but their thin-ness makes them weaker than a thicker spoke. Spokes that are thicker only at the head are "butted" or sometimes called "single-butted", and spokes that are thicker at both ends are "Double Butted". The double butted spokes were invented to save a very small amount of weight.
I recommend single-butted because a thicker nipple end will restrict the nipple from sitting in line with the spoke (the eyelet forces the nipple to sit near 90-degrees, while the spoke is at an angle). Any angle in the spoke right next to the nipple may eventually cause a spoke to break at that point. The xiongda hub on page 3 needed to keep thinner 14ga nipples, but the head could have been as large as a very strong 12ga. If building one of those again, I am told that 13/14ga single-butted spokes are available. Pedal-only wheels often do not have as much angle to the spokes as a hub motor.
http://www.ebikes.ca/shop/ebike-parts/spokes/spcust14.html
Effective Rim Diameter (ERD)
_______________________________________
ETRTO
(European Tire and Rim Technical Organization): Standards organization for tire and rim sizes
An ETRTO size marked 23-622 indicates the width of 23 mm and the tire inner diameter of 622 mm. This designation is clear and allows an unequivocal match with the corresponding rim size. [pic courtesy of http://www.presto.nl/]
_______________________________________
Spoke Pitch Circle Diameter (PCD)
This blueprint of the Bafang BPM shows a PCD of 168mm
Flange To Center width
Most front hubs have the spoke flanges equally spaced from the center of the hub, but...some rear hubs have flanges that are off-set by design, while other rear hubs have flanges centered on the motor (requiring two different lengths of spoke to work). In the pic below, the motor on the right has the spoke flanges centered on the motor, and the hub on the left has off-set flanges so all spokes can be the same length, while still allowing room for the 7-speed freewheel.
Spoke Length
The spoke length is measured from the...let's call it the "chin" of the spoke-head, so it can easily be measured by a gauge like this:
"Paladin" recommended taking an old screwdriver and cutting a notch in the tip of the blade to make snugging-up the spokes easier (since the spoke tip ends up poking out the hole if it is fully engaged on the threads, as it should be.
____________________________________________
Adding washers under the nipple or spoke head
From the Sheldon Brown site:
"...Flange thicknesses vary, but the spoke's elbow should be snug against the flange. If it is not, the spoke's tension will try to bend the spoke at the elbow -- a frequent cause of spoke breakage.
You solve this problem by sliding a small washer onto each spoke before inserting it into the hub. Most spokes will accept a 2 mm (metric bolt size) or #2 (US bolt size) washer. Brass washers are best. These are not commonly available through bicycle parts suppliers, but they can be purchased over the Internet..." (pic of washers under spoke heads http://endless-sphere.com/forums/download/file.php?id=78448)
You can also add washers under the nipple, in order to use a certain nipple in a larger rim-hole.
________________________________________________
Eyelets
Eyelets are a steel grommet that is installed to strengthen the point where the nipple puts tension on the rim holes. A single-walled rim can have a single eyelet, but a double-walled rim (recommended for heavy hub motors) can have either a single eyelet, or a double-eyelet. A "double eyelet" spreads the stress to both the upper and lower wall of a double-walled rim.
Spoke Length Calculators
http://www.ebikes.ca/tools/spoke-calc.html (my favorite)
http://www.kstoerz.com/freespoke/fullcalc
http://leonard.io/edd (recommended by Chalo)
________________________________________________
Start with the inner spokes, (tip thanks to motomech)...The next two tips are courtesy of the Steve Litt "trouble shooters" link posted by Marc S.
When you start lacing a hub to a rim, the outbound spokes are easy to install at any time, however...the inbound spokes will be restricted by any spoke that is already installed. It is recommended to install ALL of the inbound spokes before starting the outbounds.
The starting point should always be the air valve stem. it should be "boxed" with the adjacent spokes angled away from the stem:
__________________________________________________
From Sheldon Browns website:
http://sheldonbrown.com/tire-sizing.html
____________________________________________________
Spoke gauge shaft diameter in mm:
http://custommotoredbicycles.com/12_gauge_spokes_11_gauge_spokes_260mmstainless_steel12g_11g
15 gauge = 1.8mm
14 gauge = 2.0mm (common bicycle spoke dia)
13 gauge = 2.3mm (common small hubmotor ebike spoke dia)
12 gauge = 2.6mm (common large hubmotor ebike spoke dia)
11 gauge = 2.9mm
10 gauge = 3.0mm
_____________________________________________
Nipples
The nipples should have their threads fully engaged all the way up to the slot in the head. It is better for the spoke to be one mm too long, than an mm too short.
Sapim Polyax
Sapim hexagonal
Pic courtesy of the Serotta forum
_________________________________________
Put the nipple on an extra spoke in reverse, it makes it MUCH easier to get the nipple onto its destination spoke.
Motorcycle rims (seen below) have directional holes for the nipples, because the pattern is fixed. Bicycle rim sellers to E-bikers don't know if you will use a one-cross, or a 2-cross pattern, so the holes are all radial. Neil Paisnel has had some success by "angle drilling" the holes slightly in order to reduce angle-strain on the spoke, just as it exits the nipple.
In this pic, notice the nipples are radial (at 90-degrees to rim) but the spokes are at an angle, which focuses stress on the spoke right where it exits the nipple (pic courtesy of cresh):
______________________________
Pic from Offroader
LFP spoke disaster
xxxxxxxxxxxxxxxxxxxxxxxxxxx
A list of odd rim sizes, such as antique bikes
http://sheldonbrown.com/rim-sizing.html
https://www.youtube.com/watch?v=CZ3Ji72-qM4&feature=youtu.be
[youtube]CZ3Ji72-qM4[/youtube]
I am thinking about tackling my first wheel build. I may assemble a Xiongda 2-speed onto a 26-inch rim, or a Bafang BPM, and...it appears the only way to make sure I get the motor I want (BPM 10T) is to buy the unlaced motor with no spokes or rim. Also, I have read many times that when you do get an entire wheel, the spokes and rim quality are sometimes disappointing, so...any money that you saved on a pre-assembled wheel is off-set by paying more for shipping a larger box, and then needing to throw the rim/spokes away.
Offset rim
Often, a front wheel has the spoke-flanges equally spaced from the center, so the spokes from both sides are the same length. Sometimes, a rear wheel has evenly-spaced spoke-flanges, but the width of the 7-speed sprocket-cluster means in order to have the wheel-rim centered (to work properly with a rim-brake)...the rim has to be off-set nearer to the sprockets, so the freewheel side spokes need to be shorter than the disc brake side spokes.
Radial, one-cross, 2-cross lacing pattern
I am told a radial lacing is quite bad, since it doesn't allow the spokes to be able to properly do their job. A large hub in a smaller rim may have no other option (and this is why the 20-inch Magic Pie has cast aluminum spokes).
A smaller hub in a larger rim can have a 2-cross pattern, which apparently works quite well. However, if you are lacing a larger hub to a rim, you may have to settle for a one-cross pattern to avoid the spokes having too much of an angle. (pedal-only bicycles often have a 3-cross pattern, and in rare cases, a 4-cross...I have never seen an electric hubmotor where a 3-cross or more was appropriate due to the resulting extreme nipple angles)
Wheel Rims
Double-wall rims have grown in popularity, but if you are switching a single-wall rim to a double-wall, you may need slightly shorter spokes. Double-walled rims are stronger and have been developed for mountain bikes and downhill bikes. Rims often have their weights listed, and that was originally for builders who wanted to save weight. However, for an electric bike, a rim that is heavier (between two choices) is likely to be stronger.
Here is a pic of the nipple heads on a single-walled rim (pic courtesy of Sheldon Browns website)
View attachment 4
Double-butted spokes
Thinner spokes are able to flex better, but their thin-ness makes them weaker than a thicker spoke. Spokes that are thicker only at the head are "butted" or sometimes called "single-butted", and spokes that are thicker at both ends are "Double Butted". The double butted spokes were invented to save a very small amount of weight.
I recommend single-butted because a thicker nipple end will restrict the nipple from sitting in line with the spoke (the eyelet forces the nipple to sit near 90-degrees, while the spoke is at an angle). Any angle in the spoke right next to the nipple may eventually cause a spoke to break at that point. The xiongda hub on page 3 needed to keep thinner 14ga nipples, but the head could have been as large as a very strong 12ga. If building one of those again, I am told that 13/14ga single-butted spokes are available. Pedal-only wheels often do not have as much angle to the spokes as a hub motor.
http://www.ebikes.ca/shop/ebike-parts/spokes/spcust14.html
Effective Rim Diameter (ERD)
_______________________________________
ETRTO
(European Tire and Rim Technical Organization): Standards organization for tire and rim sizes
An ETRTO size marked 23-622 indicates the width of 23 mm and the tire inner diameter of 622 mm. This designation is clear and allows an unequivocal match with the corresponding rim size. [pic courtesy of http://www.presto.nl/]
_______________________________________
Spoke Pitch Circle Diameter (PCD)
This blueprint of the Bafang BPM shows a PCD of 168mm
Flange To Center width
Most front hubs have the spoke flanges equally spaced from the center of the hub, but...some rear hubs have flanges that are off-set by design, while other rear hubs have flanges centered on the motor (requiring two different lengths of spoke to work). In the pic below, the motor on the right has the spoke flanges centered on the motor, and the hub on the left has off-set flanges so all spokes can be the same length, while still allowing room for the 7-speed freewheel.
Spoke Length
The spoke length is measured from the...let's call it the "chin" of the spoke-head, so it can easily be measured by a gauge like this:
"Paladin" recommended taking an old screwdriver and cutting a notch in the tip of the blade to make snugging-up the spokes easier (since the spoke tip ends up poking out the hole if it is fully engaged on the threads, as it should be.
____________________________________________
Adding washers under the nipple or spoke head
From the Sheldon Brown site:
"...Flange thicknesses vary, but the spoke's elbow should be snug against the flange. If it is not, the spoke's tension will try to bend the spoke at the elbow -- a frequent cause of spoke breakage.
You solve this problem by sliding a small washer onto each spoke before inserting it into the hub. Most spokes will accept a 2 mm (metric bolt size) or #2 (US bolt size) washer. Brass washers are best. These are not commonly available through bicycle parts suppliers, but they can be purchased over the Internet..." (pic of washers under spoke heads http://endless-sphere.com/forums/download/file.php?id=78448)
You can also add washers under the nipple, in order to use a certain nipple in a larger rim-hole.
________________________________________________
Eyelets
Eyelets are a steel grommet that is installed to strengthen the point where the nipple puts tension on the rim holes. A single-walled rim can have a single eyelet, but a double-walled rim (recommended for heavy hub motors) can have either a single eyelet, or a double-eyelet. A "double eyelet" spreads the stress to both the upper and lower wall of a double-walled rim.
Spoke Length Calculators
http://www.ebikes.ca/tools/spoke-calc.html (my favorite)
http://www.kstoerz.com/freespoke/fullcalc
http://leonard.io/edd (recommended by Chalo)
________________________________________________
Start with the inner spokes, (tip thanks to motomech)...The next two tips are courtesy of the Steve Litt "trouble shooters" link posted by Marc S.
When you start lacing a hub to a rim, the outbound spokes are easy to install at any time, however...the inbound spokes will be restricted by any spoke that is already installed. It is recommended to install ALL of the inbound spokes before starting the outbounds.
The starting point should always be the air valve stem. it should be "boxed" with the adjacent spokes angled away from the stem:
__________________________________________________
From Sheldon Browns website:
http://sheldonbrown.com/tire-sizing.html
____________________________________________________
Spoke gauge shaft diameter in mm:
http://custommotoredbicycles.com/12_gauge_spokes_11_gauge_spokes_260mmstainless_steel12g_11g
15 gauge = 1.8mm
14 gauge = 2.0mm (common bicycle spoke dia)
13 gauge = 2.3mm (common small hubmotor ebike spoke dia)
12 gauge = 2.6mm (common large hubmotor ebike spoke dia)
11 gauge = 2.9mm
10 gauge = 3.0mm
_____________________________________________
Nipples
The nipples should have their threads fully engaged all the way up to the slot in the head. It is better for the spoke to be one mm too long, than an mm too short.
Sapim Polyax
Sapim hexagonal
Pic courtesy of the Serotta forum
_________________________________________
Put the nipple on an extra spoke in reverse, it makes it MUCH easier to get the nipple onto its destination spoke.
Motorcycle rims (seen below) have directional holes for the nipples, because the pattern is fixed. Bicycle rim sellers to E-bikers don't know if you will use a one-cross, or a 2-cross pattern, so the holes are all radial. Neil Paisnel has had some success by "angle drilling" the holes slightly in order to reduce angle-strain on the spoke, just as it exits the nipple.
In this pic, notice the nipples are radial (at 90-degrees to rim) but the spokes are at an angle, which focuses stress on the spoke right where it exits the nipple (pic courtesy of cresh):
______________________________
Pic from Offroader
LFP spoke disaster
xxxxxxxxxxxxxxxxxxxxxxxxxxx
A list of odd rim sizes, such as antique bikes
...The problem is this old 26" rim measures 24" whilst all my other 26" rims measure 22 - 22.5"...[drunkskunk] I'd say it's E.A.3, 650A, ISO 590, which is an old department store "26" size. It's an obsolete size, but you can still get tires for them...
My old 80's road bike was 27", that seemed pretty common at the time
http://sheldonbrown.com/rim-sizing.html