Prototype Disc Hub Adapter - Version 1



HI all,

As some of you may know I have been making custom sprockets for our bikes and have always sought better ways of doing things.

Since we all know about the factory 9 hole mounting system and its short comings (mainly not being able to mount the sprocket perfectly....(i.e. not having lateral run out / wobble or up and down wobble)....I began placing
the 6 Hole ISO standard disc mounting pattern on my sprockets....With this one can securely and accurately (not to mention quickly) mount a sprocket in place of the disc on a disc brake hub.

While this mounting method works for MOST all people it can POTENTIALLY cause minor chain line issues and/or interference of the sprocket with the rear frame stays on SOME frame on and wheel combinations..

The quick and easy solution for this would be to simply re-dish and/or re-space the rear wheel.....This solves the problem for most all users although this is not necessarily the best solution because re-dishing weakens the wheel to an extent and re-spacing can make cornering feel "funny" since the rear wheel would be more out of line than the front wheel.

With this, I began develop a disc mount sprocket adapter that will precisely hold a standard 9 hole sprocket (on a stock sprocket the center hole would have to be enlarged to clear the disc hub mounting area but when we sell sprockets for use with the adapter it will have the proper sized in approximately the same position as the factory 9 hole mount thus eliminating
potential chain line issues and / or possible sprocket interference with the rear frame stays.....

The hub adapters are made of the same aerospace grade 7075 T651 aluminum that we make our sprockets from. In prototype form, with the factory nuts and bolts, it weighs in at 8.8 ounces VS the stock 9 Hole mount at 13.3 ounces....I may include shorter mounting hardware as well since the factory pieces are way too long....That will make for a neater and cleaner install not to mention saving probably another ounce or two of unnecessary weight.

The photos are of the preliminary adapter....Version #2 of my adapter will ( is tight) allow full use of the rear disc brake as well.

Version #1 will be available for sale in approximately a week or so....Estimated price will be $24.50 Plus shipping

Version #2 will be available in 2 weeks or so....Estimated price will be $27.50 Plus shipping.

Questions, comments, or concerns are welcome because it would help us make a better product from the get go.

Thanks for taking time to read about our new product and for your past, present and future business!



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Looks cool. Could you show us how it would look fully installed?
Yea sometimes it can take a good hour or two to get my rear sprocket absolutely centered when I reinstalled my sprocket on Cronus after my brake mod.
I'd like to add too that on rack mounts sometimes the chain hits the frame at the front of the sprocket (looking at the sprocket installed,front meaning towards the front of the bike) because the engine is up top. When an engine is on the frame only the sprocket has to clear that area up front for your chain doesn't go by there.
man andy you are goin to town on this great work i think the one i need is the 3 pic for the rims i have if i understand it all iam still wondering about the Honda frame mount.. line up issues but what iam thinking washers could be used to move the sprocket out if needed andddddd with that being said a disk could most likely be ran in the stock place is that right ? kinda like piggy back to the sprocket
link to my rims andy what do you think ?
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HI Guys,

As far as a pic of a unit installed on a bike....I am going to try to do that BUT most likely I will have to buy a bike to do that!....Maybe a good excuse HA...Actually my bikes are all non disc brake equipped...Go figure huh?

To do my research and get my measurements I have been practically a resident at the local bike shops / bicycle retailers....Measuring, frames, hubs, wheels etc.... It seems that most mid priced pieces are somewhat similar in size....or at least within a few MM of each other.....It was a little disturbing tho that a trip to Toys R Us turned up a disc brake hub 4 MM larger than the rest that I measured....Hmmm seeking the elusive universal fit will be somewhat difficult but I feel that I will come pretty close but I may have to "loosen" up a few dimensions here and there to accomplish that....shouldn't affect performance tho....just make things a little bigger than they have to be....

As far as final "tweaking" I suppose (although inelegant) washers could be used to space things if needed....I would much prefer to get it all to work with 1 nicely machined piece of 7075 tho but that make have to be done because there are probably literally hundreds
of bike / wheel combos I haven't measured...

Concerning maintaining the use of a disc brake on a disc brake hub (the goal of my Version #2 adapter).....the disc on the bike will not be able to remain in the stock location so far as I can tell.....this is mainly because the brake caliper I think would interfere with the sprocket....My plan is to move the disc and the disc caliper outboard
and hope that enough room can be "made" for the caliper to fit in between the
disc brake disc and the drive sprocket (I did note tho that on a few "high end" bikes (it was a $4000 mountain bike but I guess not too many of us would use something like that huh?) the rear wheel stays were sooooo close to the disc already that moving the disc outboard even a 1/4 inch would not work (disc would hit the frame in about 3/16 inch).
Moving the sprocket extremely close to the spokes would help with clearances BUT may cause some chain rub if fat tires are used....In all, I am trying to have the sprocket end up where the 9 hole mount would have put it (or close to it so I can make room for the caliper)....Back to the "lab" ;-)

I bought a sprocket from you and i am finally getting my build under way. I havent been on here for quite some time and I just arrived at my chainline problem. I was trying to think of various solutions but it looks like youve got it figured out.

How much would you charge to enlarge the center bore of my sprocket if I bought an adaptor? Or do you think precision is not necessary and I could just grind the opening with shop tools I have?
Hi eerieeric.

If you you want to be able to use either of the adapters (Disc Hub Adapter or Top Hat Adapter), you would need to enlarge the center hole to clear the disc hub itself.....Precision isn't absolutely needed....Just enlarge the opening so the sprocket can slide over the part of the hub to clear disc mount area and get to the area closest to the spokes....Our sprockets for adapter use have a center hole of 2.15 inches.

If you are interested in getting an adapter, they are $29.95 each plus standard $12.50 shipping to the USA.....I was working on some pics of a Top Hat Adapter install on a disc brake bike but have been super busy of late....When I get a little free time I will do a build using the Top Hat Adapter.

Thanks for your interest.

Good luck in your build!

Im assuming i dont need the top hat. Im running newer disc/rim brake rims on an old 92 gt frame. Mild frame mods arent a big deal and im running rim brakes. I may try and talk a hobby machinist friend of mine to bore out my sprocket so its pretty. this project went from a cheap idea to a full build. go figure. I will definately order an adapter from you once I know which one I need.