The Ultimate Hub for Direct Sprocket Bolt Up

Andyinchville1

Manufacturer/Dealer
Dec 26, 2007
502
1
18
Scottsville, VA
HI All,

In reading posts that expressed a concern over the current 9 hole mounting system for the sprocket (mainly addressing the issue of spoke breakage and /or obtaining a precision alignment of the sprocket itself), I was wondering why nobody makes a high quality hub that a sprocket can directly bolt up to....

I do realize that Grubee (I think) sells a hub that this can be done BUT it is really not suitable for a multi speed rear casette / freewheel and it probably isn't of real high quality anyways (like a true high end bike part...Say for instance Shimano Dura Ace...etc...).

I was wondering if it would be worthwhile to take a hub designed for a disc brake and mount our sprocket onto it in place of the disc...This would not only provide a good spoke free mounting area for our sprockets BUT also give us a high quality, readily available, hub with multi speed capability and perfect sprocket centering / alignment (not necessarily chain line alignment but the sprocket would have no wobble or be out of true). Chain line alignment can be handled by a sprocket offset, dishing the wheel etc...Sprockets would also be able to be changed out with great speed since alignment and centering issues
would become a moot point.

Any thoughts or ideas on this?....Is the mounting area of a disc brake set up strong enough? ( I think the bolt holes are smaller and fewer but maybe high strength grade 8 could be used?)...Any experimenters out there? ;-)

Andrew

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PS - Since this post was originally made, Our Custom Sprockets are now available drilled in a dual pattern ( one set of holes to accommodate the original HD 9 hole mount and another set to accommodate the 6 Bolt IS standard for mounting the sprocket in place of the rotor on a disc brake type hub. The bolts needed for mounting a sprocket in place of a disc are said to be M8 x 15.....Any testers out there?.....The original customer that was going to try the prototype ended up having bike issues and was not able to accomplish the test.

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RedB66

Active Member
Dec 28, 2007
1,023
1
38
Sunshine State
Just thinking about the application on my bike (stretch). I need that extra clearence that the existing mount provides. As it is now my chain travels very close to my wheel (tire). I've seen hubs that are made for direct mount. I will try to find the link and post it. The link here actually goes around the hub (clam-shell) and then the sprocket attaches to it....independent of the spokes.Sprocket Adapter Mount Motorized Bicycle Moped Bike Kit - eBay (item 310013580865 end time Jan-15-08 16:00:41 PST)
 
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Andyinchville1

Manufacturer/Dealer
Dec 26, 2007
502
1
18
Scottsville, VA
HI Red,

I have seen that advertised before.....I wonder how much further outboard that would put the sprocket?....I would imagine that the disc rotor location would help you too since it is on the very outside of the hub itself (I have to admit I am a little concerned that it may be too far out and require minor redishing of the wheel itself or simply adjusting the cones a bit to keep a good chain line?)....Please keep us informed whichever route you choose....

Andrew
 

Norman

LORD VADER Moderator
Jan 16, 2008
2,605
2
38
68
pampa texas
Get that mount or something similar for the sprocket and then mount a disc brake on the sprocket and kill two birds with one stone. Something for me to think about and let someone else end up doing it. Like Exile Cycle does.
Norman.
 

Goat Herder

Gutter Rider
Apr 28, 2008
6,248
12
38
N.M.
Andy I'am on it baby this is the tickit! I got one of your aluminum jewels at hand. There is an octagon shape to a disk brake rear wheal set up for mad max playing is concerned, why not have a fitt! make the inside diameter of the sprocket tightly fit the octagon shape? then mount it traditionaly as all these sprockets have been donefor these chinas . Youl be able to enjoy the disk brake, and the sprocket as well. Kill to birds with one stone. The sprocket bear hugging the octagon shape and the spokes would be a unibody structure cheating vibe probs, and running the hub. has anybody done this I'am without a chance for now, but fully intend to try!? hope this gets more Ideas?
 

Goat Herder

Gutter Rider
Apr 28, 2008
6,248
12
38
N.M.
something else if you have a bike not set up to mount disc calipers. I would think that jigging this up by delicitly setting up the caliper by engaging it to hole it true and square, then spot welding the mounts. what ever works havent done this yet but will sometime
 

cityevader

New Member
May 11, 2008
170
0
0
Santa Cruiz, CA
I tried, but my 44t hit the rear lower chainstays...ended up grinding the rotor mounting lugs completely off and spoke mounting. Then tire rubbing on chain, dropped from a 2.1 to a 1.5 wide tire, now all good.
 

HOOKWORMRIDER1

New Member
May 21, 2008
38
0
0
Decatur Illinois
Giant bicycles makes a dics brake wheel for about $50.00 bucks.It will requiror making
your own offset sprocket.As soon as i can post pics (having problems) i will explaine
how i did it.
 

roman415

New Member
May 15, 2008
11
0
0
Just would like to give this a bump. I am a newcomer to the forums and am planning to install one of Dax's 70cc kits on my Rock Hopper mountain bike.

The Rock Hopper has disc brakes, and I was curious if any has gotten this to work.

It looks like I will have to ditch the rear disc brake if I go with the traditional spoke hub install (the brake itself doesnt look like it would clear the new sprocket)

For some reason (correct me if I'm wrong) I get the impression that you would be able to mount the sprocket to the actual rear disc, rendering it useless but providing a solid mount for the new sprocket. Does that make any sense?

I have another set of non-disc brakes that I was going to slap on in the rear but keep the front disc.

Thanks is advance
 

Andyinchville1

Manufacturer/Dealer
Dec 26, 2007
502
1
18
Scottsville, VA
HI Goat Herder....

Interesting idea about making the sprocket a slip on fit.....I may take a trip to the bike shop this weekend and look into that idea....Good thinking "out of the box"!

Andrew
 

Andyinchville1

Manufacturer/Dealer
Dec 26, 2007
502
1
18
Scottsville, VA
HI Roman415,

You are correct....Our sprockets come pre drilled to mount in place of the disc brake as well as being able to use the standard HD 9 hole mounts....Some bikes may have chain line issues when using the disc mount option (can sometimes be overcome by re dishing the rear wheel or using spacers etc...) but the 9 hole mount is always an option....
Hope this helps you.
Andrew
 

cityevader

New Member
May 11, 2008
170
0
0
Santa Cruiz, CA
Just would like to give this a bump. I am a newcomer to the forums and am planning to install one of Dax's 70cc kits on my Rock Hopper mountain bike.

The Rock Hopper has disc brakes, and I was curious if any has gotten this to work.

It looks like I will have to ditch the rear disc brake if I go with the traditional spoke hub install (the brake itself doesnt look like it would clear the new sprocket)

For some reason (correct me if I'm wrong) I get the impression that you would be able to mount the sprocket to the actual rear disc, rendering it useless but providing a solid mount for the new sprocket. Does that make any sense?

I have another set of non-disc brakes that I was going to slap on in the rear but keep the front disc.

Thanks is advance
Funny, I've got a Rockhopper too... about, oh, 10 years old (My goodness, has it been that long?!?) With Sun Rhynolite rims and Shimano XT disc hub with 9 speed cassette. The engine's driven sprocket's inner hole was smaller than the wheel's hub body. I grinded off about a 1/8 inch off the sprocket's inner radius to slip it over the hub and up against the disc rotor mounting lugs, but when the wheel was mounted, that put the sprocket hard against the frame...so I ground off the hub's disc mounts altogether to spoke-mount the driven sprocket, and it cleared fine.

If possibly you've got an old 7 speed arrangement, the wheel's dish might be reduced enough to move the sprocket closer to the "center"....but then again, I don't recall disc brakes readily available when the 7 speeds were around, but possible when 8 speeds were popular.

Note: My Rockhopper frame was right when they changed things around in 1997-ish, when I snapped the frame. It had a short one inch headset for threaded fork, but when warranty-replaced, was sent taller headtube updated to 1-1/8 for threadless forks....where was I going with this??????
I guess just reminiscing about the good old days when I used to pedal instead of motor around!
 

roman415

New Member
May 15, 2008
11
0
0
Thanks for the responses!

I am still waiting on my kit to show up (hopefully today or tomorrow *fingers crossed*.) I will post pictures and let you know about clearance.

I mistakenly said i have a rockhopper, what I really meant was Hardrock (I got half of the name right :p)

I actually have 2 hardrocks, one has a smaller frame (my bro's,) so i do have the luxury to pick out the one that will work best with the kit.

Will keep you guys posted.
 

Andyinchville1

Manufacturer/Dealer
Dec 26, 2007
502
1
18
Scottsville, VA
HI Guys....

Because of the amount of interest in mounting our drive sprockets in place of the disc brake on a disc brake hub....I decided to build an adapter that will offset the sprocket closer to the spokes (places the sprocket in generally the same position that the original 9 hole mount would have placed the sprocket)....The reason for this is because some frame and sprocket combinations did not work for some people (chain rubbing the rear stays or too extreme a chain angle)....for most the solution was as simple as redishing the wheel and / or spacing the rear wheel......Tho functional....this is not optimal since it can compromise rear wheel strength...the adapter takes care of all this without need to redish or respace (Basically the sprocket (with enlarged center) is bolted to the adapter and the adapter is bolted to the 6 holes of the disc brake mount)...If I shave some of the adapter behind the 6 bolts there may be enough room for the disc caliper?...Will the disc on the disc brake still work if I space it out 1/8 inch?....I will post pics soon....

PS - I can possibly make the adapter so that the sprocket and disc brake disc can be used BUT since I do not own a bike with a disc brake I'll have to take a trip to a bike store to check them out.....