Need a new rim in my rear BAFANG wheel !!!

[bilabonic]

Hi All

Never had much luck with the wheel from new, loose spokes constantly and had it aligned in Halfords and the old guy said he did 'his best).

Anyway i have hit a curb 'hard' and it is badly buckled (virtually unrideable) BUT what i have noticed is the join on the rim is splitting and that has always been a problem area.

What are my options guys ? New rim/rebuild ??

Where would i get a suitable replacement ???

Anyone advise as it's off road for now as unsafe !!!!

Cheers

 

[jerrysimon]

Where do you live ?

I would suggest new rim, spokes and a rebuild. I can build wheels and I guess would do it for cost of parts if you live close. I am in Cambridge.

PS Front or back ?


Regards

Jerry

 

[Deleted member 4366]

The main problem is the cost of sending it anywhere. You might be able to buy a motor wheel from Kudos for about £120 if you ask them nicely, or maybe from Woosh. If you go that route and you have a hall sensor connector on yours, make sure you get one on your new one. Catsnapper does a good job, and isn't too expensive, but I think he's in Spain at the moment. You can get rims and spokes on Ebay; however, you need the ERD to calculate spoke length, and they often don't give it.

 

[bilabonic]

What is the ERD, i noticed the spokes are 12G, i am in South Wales but doubt it would cost much to post with Myhermes or similar, it MIGHT be salvagable but i'm no expert, but there is definately a hairline fracture in the rim.

So any 26"x1.75" rim would do ? Surely i could just remove a spoke and measure it ?

Cheers guys

 

[rpurchon]

first thing get a new rim.try chain reaction cycles.then take it from there .
chances are the spokes will fit.if you buy a rim that looks similar in section.
richard

 

[Sacko]

Do these look like the rims?

Double Wall Aluminum Alloy Rim - BMSBATTERY

They have the ERD measurements too.

 

[Deleted member 4366]

The ERD is the Effictive Rim Diameter, which is a strange measurement that's necessary to calculate the spoke length. You could buy any rim, but the chances are that the spokes won't fit; however, once you have it, you can compare it with your existing one to see whether you want longer or shorter spokes. The 515mm ERD of the BMSbattery rim is totally wrong on their website. The actual is closer to 540mm from memory.

 

[bilabonic]

It has 26"/1.5" written on it, but i guess you need the ERD for spoke size as its just around 26" with the tire inflated.

But spoke size also hub size dependant so i can not see how it could be calculated anyway ?

Yep, thats the type Sacko, i only ordered another two chargers from there last week as well.

Some spokes are buckled slightly, but god knows the mm of them.....

Might try a motorcycle shop or Tredz near me ????

 

[Deleted member 4366]

The problem with rims is that the depth of the rims vary so much. I bought one on Ebay for my CST motor. It looked similar to the one I had on my BPM motor, so I ordered the same length spokes, but when I tried to build it, the spokes were miles too short, so I had to pinch a rim from another motor.

 

[bilabonic]

Right think if had a bit of luck here, BMS is allowing to add to order, just need to know size of spokes an will get rim above or 3.....

I measured the spokes and they are 2.6mm/12 gauge.

 

[Deleted member 4366]

I just looked at my Q128 That has 36 13g spokes in a one-cross pattern on the standard BMSBattery rim
The spoke flange diameter is 130mm, and the flanges are 50mm apart. The spokes are 210mm long

Using this spoke calculator, it gives a spoke length of 209.9mm when I enter an ERD of 539mm.

Edd, an easy to use spoke calculator

A Bafang QSWXK5 has a spoke flange dia of 121mm with the flanges 50mm apart.

When I enter those dimensions into the calculator with the same 539mm ERD, but using a two-cross pattern, it gives 226.7mm. If you want to use 12g in a one-cross pattern, it would be 213.9mm

 

[bilabonic]

I just looked at my Q128 That has 36 13g spokes in a one-cross pattern on the standard BMSBattery rim
The spoke flange diameter is 130mm, and the flanges are 50mm apart. The spokes are 210mm long

Using this spoke calculator, it gives a spoke length of 209.9mm when I enter an ERD of 539mm.

Edd, an easy to use spoke calculator

A Bafang QSWXK5 has a spoke flange dia of 121mm with the flanges 50mm apart.

When I enter those dimensions into the calculator with the same 539mm ERD, but using a two-cross pattern, it gives 226.7mm. If you want to use 12g in a one-cross pattern, it would be 213.9mm

How are my spokes 2.6mm ? Thought that was 12G, they are definately thicker than my normal front wheel of 2mm -

Straight Gauge: 12, 13, 14, and 15 ga. (2.6, 2.3, 2, 1.8)

How did you tell they were 13g Dave ?

BMS have mailed stating they are 13G / 217mm ???

 

[Deleted member 4366]

BMSBattery use 13g spokes on all their kits, mainly 2-cross, but sometimes 1-cross. IIRC 8Funbike use 12g 1-cross. Who said your spokes are 2.6mm?

If you already have a BMSBattery rim, you can take a spoke out and measure it. Alternatively you can compare your rim with my BMSBattery one. I stretched a piece of string from one side to the other over the hub, and it came to about 540mm. If I could measure it in a straight line, it would be about 535mm, which is about right for an ERD of 539mm. There's a description of ERD here. I don't think you'd be far off if you took the inside diameter and added 5mm. to allow for the thickness of the rim and spoke-head.

Unicycle.com - Spoke Calculator

 

[jerrysimon]

This is another calculator that also shows you how to measure rim sizes and calculate the size of spokes you need based on your hub dimensions.

Spoke length calculator for calculating spokelengths

Click the help button at the very top to show your how to carry out measurements which you then enter into the calculator to work of spoke size required.

Regards

Jerry

 

[bilabonic]

Cheers guys, my micrometer says 2.61mm.

Learned A LOT from this site than any other, had a reply from Andy from Kudos so very impressed with them !!
He only has 250w wheels in stock though.

 

[Sacko]

You don't need a whole new motor etc, just lace your old one into a new rim.

I have a 26" rim here, but the ERD is 542mm. I would even use the old spokes too, bent or not.

 

[Deleted member 4366]

Cheers guys, my micrometer says 2.61mm.

Learned A LOT from this site than any other, had a reply from Andy from Kudos so very impressed with them !!
He only has 250w wheels in stock though.

Wait a minute. Are you saying it's your BPM wheel that's damaged, in which case I can tell you that the spokes for the BMSBattery rim are 210mm in a 2-cross pattern?

 

[bilabonic]

Yep. Think they are 12g/210mm.

I emailed sales and customer care and had two different answers ?

Need another charger as one has just stopped working ?

Will also get rim. Couple other spares as well.

 

[cwah]

Catsnapper is on holidays now. Do you know anyone that can cut spoke to size?

 

[Sacko]

BMS battery sell 12g spokes in a variety of lengths.