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No Title -> Tires/wheels/braking -> How to add disc brake rotors to bicycle wheels
Post Info TOPIC: How to add disc brake rotors to bicycle wheels
Functional Artist


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How to add disc brake rotors to bicycle wheels
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Hello all,

Pro EV posted about Electrathon America on DIYELECTRICCAR

...& got me interested/inspired in the sport

 

Now I'm working on building an Electrathon car

...& after lots of research, I still haven't seen much info about adding disc brake rotors, to bicycle wheels

...& hope some of you guys could comment on this & help me learn more, about my new endeavor 

 

The rear rim, that I have, has threads on the outside of one side of the hub, for attaching a freewheel unit

SAM_0073.JPG

I've noticed that some large diameter (like 26") front wheels also have outside threaded hubs with an adapter threaded on & a rotor bolt to it

...but, not any smaller ones (like ~20")

 

This is an example of the adapter:

 Bicycle Freewheel Threaded Hubs Disk Disc Brake Rotor 6 Bolt Flange Adapter 48mm | eBay

 

According to the ad (& other ads) these threaded hubs have a 48mm distance across the bolt holes for use with rotors like these:

 US 1/2pcs 140mm/160mm/180mm/203mm MTB Road Bike Disc Brake Rotor fit Spyre HY/RD | eBay

...& seem to have 34mm RH threads 

...but, they don't mention the pitch (1mm, 1.5mm 2mm?)

 

Looking into it further I found:

Traditional Thread-on Freewheels (sheldonbrown.com)

 

Freewheel Threading

The standard ISO threading for freewheels is 1.375 x 24 TPI, the same as for standard ISO bottom brackets.

TypeInchMetric
Italian1.378" x 24 tpi35 x 1.058 mm
ISO1.375" x 24 tpi34.92 x 1.058 mm
British1.370" x 24 tpi34.80 x 1.058 mm
French1.366" x 25.4 tpi34.7 x 1 mm
Metric BMX1.181" x 25.4 tpi30 x 1 mm

 

 

I have a couple of 20" BMX bicycle wheels that has an ~35mm aluminum hub, that protrudes ~1/4" from the rim (on each side)

...& was thinking about (maybe) trying to thread the outside of this hub, to accept an adapter (like mentioned above) that a rotor can be mounted onto

 

Does anyone think, this will work?

...or has anyone done this?

...or seen this been done before?



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Archer321


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The problem with threaded adapters for brakes is that unless you can make one of them with left-hand threads then one side will always be trying to unthread itself as you brake. You're much better off to just buy wheels (or hubs if you are into spoked wheels) that are made for disc brakes already. I've got some 14" ones on my website. Take a look. 

https://www.electrathonparts.com/store/p/14-front-wheel



-- Edited by Archer321 on Saturday 9th of September 2023 03:41:16 AM



-- Edited by Archer321 on Saturday 9th of September 2023 03:42:34 AM

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Functional Artist


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Hey Archer,
Thanks for the reply.

I've checked out some of your karts

...& I must say "nice work"!


I agree & unthreading was one of my concerns too.


Looking around I came across this kart

SAM_0443 (1).JPG

Especially the front wheels

SAM_0444 (1).JPG

So, I made up some hub rings

...drilled some holes

...& used some Loc-Tite to bond a brake rotor adapter to the BMX bicycle wheel

...& then, ran 3" Stainless Steel

 

bolts thru the hub rings, rotor & adapter & wheel to increase the strength & durability with a mechanical bond too.

SAM_0493 (3).JPG

Other side

SAM_0494 (3).JPG



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Functional Artist


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I upgraded the stock bicycle bearings on the front wheels
...with (4) RS8 bearings

These bearings are much higher quality
...& also facilitates the upgrade from the stock 3/8" bicycle axle, up to 1/2" Grade 8 bolts

Some .025 shim material was required for the bearings to fit "snuggly" in the bicycle hubs
...& I used some Loc-Tite bearing retaining compound to "glue" the bearings & shims into the hubs biggrin

SAM_0533 (3).JPG



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Archer321


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Well there ya go! Hopefully that'll work out well for you. Where are you located and when do you anticipate getting in a race?

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Functional Artist


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Hey Archer 321,

I'm just designing, creating & building right now
...but, will be testing soon.

I'm in Toledo Ohio

It seems like the closest Electrathon racing, near me, is in Michigan
...but, they seem to go by the Challenge USA rules

I started designing & building Polaris based on (& in compliance with) the National Electrathon rules
...& then, found out that there are several different rule book variations, depending on where you want to race

So...maybe it'll just be a prototype/test vehicle
...but, I'm going to be racing around in it either way biggrin



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No Title -> Tires/wheels/braking -> How to add disc brake rotors to bicycle wheels