View Full Version : disc rotor adapter

03-25-2009, 01:42 PM
Ok, folks.....here's the deal:

I bought a pair of FRONT BMX wheels with 14mm axles, (ebay) for my next Tadpole project.

I was looking at them yesterday..... the hubs are threaded on one side.
I have one threaded disc brake adapter that fits the hubs. (woohooo....disc brakes.....so I thought.) link to pics, below

also....the axle bolts are only 13mm...so they seem! (the axles are 1/2" fine thread, SAE !! go figure? )

Off to my LBS...... Josh says...."dude, those are REAR wheels!!"
he proceeds to screw-on a freewheel sprocket!! Dang!!

no worries.... turning the wheel around & using my screw-on disc adapter will work out just fine for me.....woohooo!! my next tad will have disc brake front wheels!! If I can find another screw-on rotor adapter....?

my problem...... Josh has NEVER seen this type of rotor adapter. & we couldn't find one in his parts catalog!! there are clamp-on adapters, for splined hubs.

link to pics: http://cid-7ba95982bbf33751.skydrive.live.com/browse.aspx/Tad%20wheels
has anyone seen these adapters??
any ideas.......?

thanks in advance

Radical Brad
03-25-2009, 02:34 PM


03-25-2009, 02:47 PM


So I may be dense but I'm trying to understand.

Do you have to then use 2 rear wheels for your Tadpole front tires?

Or is this to put a single disk on the rear wheel?

If you are threading it onto the freewheel, how do you put the rear cassette (or gears) on the other side?


03-25-2009, 04:57 PM
If you were using it on a rear wheel, you would have to use a flip flop BMX hub, which has threads for large freewheels on one side, and threads for smaller freewheels on the other.

03-25-2009, 05:27 PM
thanks for the link, Brad. that ought to do the trick!!

the ebay seller sent me two rear wheels, by mistake..... I will use these on the front.

I can't complain... I got BOTH these wheels for 40 bucks....shipped!!

what do y'all think of the 1/2" axle? I thought everything was metric, these days.

John Lewis
03-25-2009, 10:42 PM
If I understand rightly you intend putting disks on the front using the threaded freewheel mount and an adapter.

The problem I see is how to lock the adapter which is a right hand thread on the left wheel. The braking forces will try to unscrew it. Do a seach of the forum I recall quite a lot of discussion on this a while back.

Perhaps I'm missing something.

John Lewis

03-26-2009, 02:29 AM
The problem I see is how to lock the adapter which is a right hand thread on the left wheel. The braking forces will try to unscrew it. Do a seach of the forum I recall quite a lot of discussion on this a while back.

That's exactly what I had on the Fox. It worked out fine for the right wheel, but the left wheel is a problem. The braking forces tighten the right adapter, but loosen the left adapter. There's no room for a lock ring as there would for a flip-flop hub with a screw on cog on the left side of a rear wheel.
I tried golf shafting epoxy to hold the adapter in place, thinking if it holds a clubhead going 100+mph and smackig a hard ball, it should hold the adapter. It failed after a few miles. I tried JB weld, that didn't work either. I tried pinning them in place, but you could only set the pin the thickness of the hub and the bearing cup. The braking forces ripped the hub apart. The adapters are aluminum, so you can't weld them to steel rims. I bought steel adapters from electricscooterparts.com, but they don't have the same thread pattern as bicycle discs, so you would need to buy discs that fit. This would seem to be the cheapest solution, as long as you feel comfortable with 36 spoke wheels, or can find 48 hole steel hubs. Any tadpole with SA drum brakes (Like some Greenspeeds) have 36 spoke wheels. I haven't had any problems with the SA drum hubs, They stop on a dime.
electricscooterparts.com now sells two steel adapters, maybe one of them will accept bicycle discs. You could call and ask. Scroll down the page to find the adapters, as well as left and right calipers.


03-26-2009, 08:09 AM
I knew there were going to be issues with the left wheel. I was thinking red threadlocker & a set screw.
I need to think harder!

Thanks for the heads-up & the links!!! You saved me a bunch of grief~~ (& $money$)

I'll do some more reading here....

thanks again!!

03-26-2009, 11:17 AM
I would have gone with steel 36 hole hubs and welded the steel adapters on, but I found a good deal on the SA drum hubs and went that route instead. It ended up costing only 20 bucks more.