Crack developing on ebikeling rim sidewall-- need to repair

[99t4]

By repair I mean replace rim and spokes with appropriate good quality components.



Hopefully I can improve on some of the build aspects that were suboptimal for my application, such as (all to common on commodity dd hub/wheel kits) overly thick spokes, and 19mm rim too narrow for the tire size I run (26 x 2.35).

It's my first wheelbuilding project so I plan to take it to a local experienced bike mechanic who works out of his garage, and is OK with having me watch and learn.

I have measured the hub flange diameter (230mm), flange spacing (36mm flange center to center), and offset (50mm L flange to outside washer, 48mm R flange to outside washer) of the 1500w ebikeling hub. Currently I am in the phase of feeding the measurements into the Grin spoke length calculator.

In a recent post, Chalo made a good rim recommendation, but the vendor cannot supply the spoke hole offset measurement. How important is it?

voilamart/otherbrands wheel rim

I am in central PA. I need a wheel rim (or the whole wheel with spokes and motor if the price is right) that the voilamart conversion kits sell. The rim is a 26", has 36 holes that fit gauge 12 thick spokes and the rim depth is 3cm or 30mm (i.e. the distance between nipple and outer rim radius)...

endless-sphere.com

Also, I am not yet able to measure the hub flange spoke holes but presume these spokes (recommended by Chalo and AW) can work well with common hubmotors?

Sapim Strong Single Butted J-Bend Spoke

A butted spoke is drawn to its specific profile, which defines its high strength. The strongest spoke in Sapim’s product range, the Strong is developed for specific and heavy usage such as tandem, e-bikes or heavy load use. In case of large hub holes, the Strong is the recommended choice...

wheelbuildingparts.com

 

[amberwolf]

I have measured the hub flange diameter (230mm), flange spacing (36mm flange center to center), and offset (50mm L flange to outside washer, 48mm R flange to outside washer) of the 1500w ebikeling hub. Currently I am in the phase of feeding the measurements into the Grin spoke length calculator.

You may want to setup the numbers with all elbows out to get the best bracing angle. (simulates having a wider flange). My 20" hubmotor wheels were built with all elbows in and worked fine, but AFAIK should be laterally stiffer the other way.

If the motor flange spoke holes are large, you may need spoke washers on the heads of the spokes before you pass them thru the holes. Don't make the mistake I once did and just get washers that sort of fit the heads at the hardware store ...get actual spoke washers intended for the purpose and size of spoke you are using.

Last time I had to deal with large-holed flanges, I opted to use the drill press to drill new smaller holes in my MXUS 450x motor's flanges sized to fit the 13/14 spokes used, since the original holes in the flange were so big I think it'd've fit 11 or even 10g, :lol: (I think I measured them but don't see that in my posts at the time of the mod).

In a recent post, Chalo made a good rim recommendation, but the vendor cannot supply the spoke hole offset measurement. How important is it?

voilamart/otherbrands wheel rim

I am in central PA. I need a wheel rim (or the whole wheel with spokes and motor if the price is right) that the voilamart conversion kits sell. The rim is a 26", has 36 holes that fit gauge 12 thick spokes and the rim depth is 3cm or 30mm (i.e. the distance between nipple and outer rim radius)...

endless-sphere.com

If you mean the SE Bikes J35S rim here

SE Bikes J35S Rim

Carson City Bike Shop for all of your bicycle parts and accessories. We have daily discounts on tires, tubes, brakes, cables, forks, and many other components

carsoncitybikeshop.com

They don't look offset from the centerline of the rim very far, a few mm at most. You could probably just guesstimate that distance based on the stated rim width and the visible distance across the rim in the image vs the visible distance of the holes from the centerline.

Size:	26in	Brand:	Se Bikes
Model:	J35S	ISO:	559
Width ID:	35	Width OD:	40
Profile:	21.5	Wall:	Dbl
Side:	NMSW	Color:	Black
Hole Count:	36	Valve:	SV
Tire Compatibility:	Tube Only	Search Color:	Black

Also, I am not yet able to measure the hub flange spoke holes but presume these spokes (recommended by Chalo and AW) can work well with common hubmotors?

Sapim Strong Single Butted J-Bend Spoke

A butted spoke is drawn to its specific profile, which defines its high strength. The strongest spoke in Sapim’s product range, the Strong is developed for specific and heavy usage such as tandem, e-bikes or heavy load use. In case of large hub holes, the Strong is the recommended choice...

wheelbuildingparts.com

AFAIK those are the same brand/model spokes I have on my SB Cruiser motor wheels in the rear that carry most of the weight of the trike and the 200-300lb cargo loads I carry regularly for grocery trips (about monthly-ish). Their image looks different from the ones I got from Grin here

Sapim Strong 13-14g Butted Spoke, Silver

Custom Cut Silver Sapim Strong Spoke, Butted 13-14 Gauge, Includes Nipple

ebikes.ca

but they should be the same thing, and despite impacts that have broken axles and folded the edge of the rim down, distorting the rim shape a bit, the spokes didn't break....

The difference is that the thicker part on the spokes at WBP is much shorter than that of the Grin ones, which should make them *better* at being able to be correctly tensioned especially for shorter spokes, without stressing the rim.

They are what I would probably still use if I had to buy spokes to build a new wheel again. If I were to ever build the v2 of SBC, I would probably use 14/15g instead (AFAICR that's what is on my front 26" regular wheel) to see how they hold up. (I'd just carry a spare wheel with me just in case they did fail; the new trike is being designed with a space for two; these would be plain bicycle wheels rather than hubmotors, as all the wheels would be chain driven from frame-mounted motors).

 

[99t4]

Maybe I'll look for another suitable rim that I can get all the important dimensions. Since this is my first wheelbuilding project I don't want to mess up on the spoke length calculations.

I'll go check the spoke length calculator again plugging in different rim spoke hole numbers and see if it appreciably changes to overall spoke length recommendation.

 

[amberwolf]

How much it changes the overall length depends on the angle at which it meets the rim. The closer to 90 degrees that is, the less it will matter, meaning the longer the spoke-to-hub distance, the less of the total length will be the offset from centerline of the rim.

 

[99t4]

Spoke calculator gives 76.4 deg. spoke angle.

The definition for flange spacing: "Flange Spacing: This is the distance between the left and right spoke flanges, as measured from center to center."

If I am doing all elbows out, shouldn't my flange spacing measurement be from the outboard surfaces of the flanges?

 

[amberwolf]

If the calculator has a separate choice for elbows out vs in, then no, it should take a typical flange thickness into account (which you can test by doing it both ways and seeing a different result each way).

If it can't tell the difference, then I'd expect to need to use the specific measurement for the distance you have.

But realistically, it's a tiny amount of distance and I doubt it would affect the calculation enough to worry about.

 

[Chalo]

Maybe I'll look for another suitable rim that I can get all the important dimensions. Since this is my first wheelbuilding project I don't want to mess up on the spoke length calculations.

Not all the dimensions are important. Discrepancies in center-to-flange and lateral offset dimensions only introduce small sine errors that hardly ever shift your result even to the next mm spoke length. Spoke hole diameter only changes the result by the difference in radius of the spoke wire.

The dimensions that make significant changes in spoke length are ERD, hub flange pattern diameter, and cross count.

Hole lateral offset, or what I call "stagger", only became a feature of spoke calculators after the introduction of off-center drilled rims for dished wheels. Taking it into account is also important for very wide rims with an extreme amount of stagger, like most fatbike rims. But some rims have used slightly staggered holes for ages, and we never bothered to add that factor into the spoke calculations until recently.

 

[99t4]

BIG thanks AW and Chalo on your most recent posts here. I just needed some helpful direction of reason from some experienced reputable forum members. Helps me get a handle on this now, my first wheel (re)building project; measure twice, cut once.

Your explanations are entirely logical and (now that I understand the geometry better) common sense.

BTW, I took the hub measurements following the processes described in this entertaining Grin Tech video:

How to Measure Hubs and Rims for Perfect Spoke Lengths, Ebike Hub Motor Wheelbuilding

As the hubmotor is still laced up to the rim.

 

[Slowchris11]

Make good pictures of your wheel still assembled. Will be of great help with the rebuild.
Take out one spoke of each side and measure what you have got.
Then take the old rim and calculate the real difference to the new rim.
This is simpler, as you only have to change a single factor, instead of doing a whole new calculation with all possible tollerances. Supplier dislike taking back spokes.
If you take stronger spokes, you have to add half of the difference on the hub to the length, as the center moves up.
If you need to drill out the holes, this changes, again.
You will need different nipples as well. Analyze the old ones and compare how the threads are positioned inside. You want the thread to vanish inside the nipple and, best, cut a little into the soft nipple.
All these points are fractions of an inch /milimeter, but they add up and can ruin your day.
It is a very complicated process to get such a build perfect, not only a fit from the outside.

Last, make a theoretical calculation with some online tool. If the results match you are good.

 

[99t4]

Measuring the existing spokes and back calculating from their length presumes the original buildup (commodity motor wheel kit with too-thick spokes and cheap rim) used the proper length spokes, no?

If you take stronger spokes, you have to add half of the difference on the hub to the length, as the center moves up.
If you need to drill out the holes, this changes, again.

Sorry, didn't understand. Can you please clarify?

 

[Slowchris11]

You have an old, once working wheel and can remove a spoke (two to be exact). Now you can check the build for problems. You can consider this when ordering new spokes. At least the wheel worked until you wore out the brake rim. So you end up with a correct spoke length.
You only have to modify it for the new nipple position in the new rim, the thread length of the spoke and thread position in the new nipple.
You find these data in the drawings from the manufacturer.

"Sorry, didn't understand. Can you please clarify?"

If you order stronger spokes, you have to compare the diameter of it, as it changes the position in the hub hole.
For example, if the hole in the hub stays the same, as it is large enough and the spoke is 1mm thicker, the thread end of the spoke moves up 1/2 of a milimeter.
Making it half a milimeter shorter.
If you drill the hole in the hub 1mm larger, you compensate for this.
This may be just a very small difference, but with all your measuring errors and part tollerances, these add up.
Do we agree you want the most exact build you can get? If you want to ignore something, you should know about it.

As I wrote, the spoke thread should meet the nipple thread in a very special way, cutting into the soft nipple material . This reduces the chance of the spoke to break at the thread. So a milimeter may be the difference between a hit and a close miss.

In a factory making custom wheels, the spoke lenght is measured and then the spokes are cut and threads rolled into them. They do not use universal spokes of pre cut length. They use a machine for it, of course. The result are thread ends that meet in the nipple, which at the same time secures them.
Try it. You can screw the spoke all the way into the nipple and then use a little force. The steel spoke works like a tap drill.

 

[99t4]

Spoke calculator gives me 168mm length (going with the Sapim Strong 13-14 ga single butted spokes recommended above).

Now I am confused deciding which nipples to order. I want brass, but the lengths range from 12mm - 18mm. What determines the correct nipple length?

 

[docw009]

If the nipples are fully threaded inside, then an 18mm nipple would run out of thread on a spoke and be effectively 6mm longer than a 12 mm nipple. If they only thread the last 8-10 mm , then maybe the 18 mm is designed to have a longer body that might add more strength to the assembly? I am just speculating, but believe the latter is true. Otherwise, nipple length would be factored into a spoke calculator,.

I've always bought the spokes and nipples at the same time. I took apart an ebikeling wheel seven years ago, and spoked the motor into a 26" fat tire rim. Used no-name 13G spokes from ebay seller childhood_dreams, far better than whatever came on the wheel. On subsequent wheels, I migrated to Sapim Strong 13G-14G from Yojimbo in Chicago.

 

[Chalo]

Different nipple lengths are for rims with different depths or shape at the spoke bed. Long nipps also provide a longer, harder to damage tool interface. No nipples are threaded end to end; the thread is always counterbored at the square end. If the thread is longer in a long nipple, it's only by a small amount.

I use long nipps if I'm concerned that the thread might peek outside of short ones because the spokes are slightly too short.

My favorite nipple to use is Sapim because it's very consistent in size/tool fit, and because it's harder and more resistant to smooshing or rounding off than say DT Swiss nipples. 14mm is my preferred length for those, for most rims.

 

[99t4]

My favorite nipple to use is Sapim because it's very consistent in size/tool fit, and because it's harder and more resistant to smooshing or rounding off than say DT Swiss nipples. 14mm is my preferred length for those, for most rims.

Good info, thanks. That must be what they list as "Silver Brass 14mm Sapim."

I've always bought the spokes and nipples at the same time. I took apart an ebikeling wheel seven years ago, and spoked the motor into a 26" fat tire rim. Used no-name 13G spokes from ebay seller childhood_dreams, far better than whatever came on the wheel. On subsequent wheels, I migrated to Sapim Strong 13G-14G from Yojimbo in Chicago.

Sent an email to them, looks like their online store has been down for some time.

 

[99t4]

As I wrote, the spoke thread should meet the nipple thread in a very special way, cutting into the soft nipple material . This reduces the chance of the spoke to break at the thread. So a milimeter may be the difference between a hit and a close miss... The result are thread ends that meet in the nipple, which at the same time secures them.
Try it. You can screw the spoke all the way into the nipple and then use a little force. The steel spoke works like a tap drill.

It felt like I achieved this, at least on several of the spokes. At first, I was thinking the spokes were too long, as there was so much slop and play in the assembly. But after driving the nipples in all the way it all tightened up. Some felt like they reached the ends of the threads and maybe a bit beyond. Visually the ends of many of the spokes are extending beyond the far end of the nipple.



Also, the hub flange is not capturing the base of the J-bend. Am I understanding correctly that presents a possible future breakage problem?

 

[Slowchris11]

The bend of your spokes is too wide. There are differend spoke bends to fit different hubs. Usualy you take one of the old spokes from the hub as a sample. You can solve the problem by putting a washer on the spoke, then fit it to the hub. This is a common practice and you can order these, usually made from brass, where you got the spokes from. I have no real world experience how critical this will be if you use it as is, but IMO the hole in the hub might wear out and the end of the spoke will see more bending force. I can imagine how much you will dislike it to put all the spokes out and in again.

https://www.wheel-parts.shop/en/sapim-spoke-washers.html

 

[Sturmey]

Also, the hub flange is not capturing the base of the J-bend. Am I understanding correctly that presents a possible future breakage problem?

View attachment 338916

Re above, I often put on a thick pair of gloves and with both hands (a hand at each side of wheel) squeeze the opposite pairs of spokes. I then retention the wheel spokes as they loosen after this. I then repeat again (and again) and retention if necessary. This has worked for me with 14g spokes and softer galvanized 13g spokes and the spokes ended up wrapped snugly at the hub. It does not work well for me with the harder 13g stainless steel spokes. Your spokes may be too long for this if you are running out of tread.
PS. Link below might explain this better than me.

Pre-stressing Spokes Why? How?

Why would you need to prestress spokes to improve the ride of the cyclist? We just send cyclist out the door with new bikes or new wheels and tell them to come back in 30 days to get them tighten the spokes up again (but in reality we only true the wheels). Is this how your shop operates? If not, yo

www.linkedin.com

 

[99t4]

I stress-relieved the wheel by three methods: squeezing spoke pairs with heavy gloves, twisting a stick between them, and pressing down on the rim with the hub placed on a heavy cardboard tube pedestal. The resulting pings were satisfying, almost like cracking knuckles.

Then added rim tape, installed tube and tire. A 20 minute test showed no perceptible spoke loosening or out of true. I will take it for a > 1 hour test later today and continue to closely inspect until it proves to have settled down.

 

[99t4]

After a one hour test over a typical ride (mostly rough pavement, numerous poorly maintained rough RR crossings, gravel, some curbs, 45MPH swoop down Wahoo Hill, etc.) the wheel seems to be holding up.

(Surprising?) first impressions:

• Feels much much more connected to the road, more confidence-inspiring
• 
  
• Tracks better in turns (used to hop around unpredictably on turns)
• 
  
• Smoother
• 
  
• Quieter

The original wheelbuild must have really been suboptimal and/or badly deteriorated. A "commodity" 1500w Ebikeling DD 26" with thick (13 or maybe even 12ga?) spokes and narrow 19mm rim.

I attribute the new improved performance to:

• Better, high quality rim and spokes
• 
  
• Appropriately sized spokes (13/14 ga butted)
• 
  
• Wider rim more appropriately sized for my preferred 2.35" tires (currently running Schwalbe Crazy Bob 26x2.35).
• 
  
• Better ( but not perfect) spoke tensioning

My first wheelbuilding project, and admittedly I was apprehensive as this is my daily driver transportation and couldn't afford much downtime. I am glad I have tackled this challenge which gave me a great feeling of satisfaction. Thanks to all here who have helped.

Main thing I would change for the next time: I lubed the nipples by pouring some motor oil in the plastic bag they came in and massaged it around. While this insured the threads and seating surfaces were well lubricated it was messy and tricky to work with. Does anyone have a better process?

 

[nicobie]

Congratulations! Looks like you have taken a big step forward.

Not only do you have a better product but you have picked up another skill too.

 

[amberwolf]

Main thing I would change for the next time: I lubed the nipples by pouring some motor oil in the plastic bag they came in and massaged it around. While this insured the threads and seating surfaces were well lubricated it was messy and tricky to work with. Does anyone have a better process?

Needle dropper to put one teensy drop of machine oil on the threads; takes very little lube to work. Same dropper to lube the seating surface while the nipple is installed and already touching the rim's hole.

Dunno about now, but wheelbuilders used to use boiled linseed oil to lube the threads, because it hardens and acts as a kind of loctite afterward. You might check out Jobst Brandt's The Bicycle Wheel for good info. (you can start at Sheldon Brown's wheelbuilding pages)

 

[99t4]

Needle dropper to put one teensy drop of machine oil on the threads; takes very little lube to work. Same dropper to lube the seating surface while the nipple is installed and already touching the rim's hole.

Thanks! Great idea! I do have Tri-flow in a dropper spout bottle.

 

[Chalo]

Thanks! Great idea! I do have Tri-flow in a dropper spout bottle.

I use the Tri-flow pipette bottle to apply just enough of a drop that it runs down into the threads and then overflows into the rim hole. Tri-flow is intensely wicking, so it gets to everywhere it needs to be.

When blackish smudges aren't an issue, I use Dri-Slide Bike Aid moly disulfide lube, which tolerates extreme pressure and doesn't weep away over time.

 

[99t4]

When blackish smudges aren't an issue, I use Dri-Slide Bike Aid moly disulfide lube, which tolerates extreme pressure and doesn't weep away over time.

Seems similar to this, which I already have in the toolbox. Was described to me as molybdinum disulfide.