68 Spoke wheel help needed

[DutchDude]

Like Duane already predicted - I am having problems fitting the sprocket. But my wife choose the bike, so I am kinda stuck with it

As you can see in the first two pictures, there are two problems.

1. The hub is 70 mm, and the inner diameter of the holes in the sprocket is 65 mm

2. Too many spokes, so the bolds don't line up.

http://i114.photobucket.com/albums/n267/DutchDude_2006/Moped_007L.jpg

http://i114.photobucket.com/albums/n267/DutchDude_2006/Moped_008L.jpg

As you can see, you can actually see the hub through the bold holes. As well as the many obstructions of spokes

 

[DutchDude]

Possible solution?

So, what I was wondering is if I have enough of a flange on the hub to drill holes directly through it? It looks like I have about 11 mm to work with:

http://i114.photobucket.com/albums/n267/DutchDude_2006/Moped_005L.jpg


- Would this be strong enough?

- What material should I use between the hub and the sprocket?

- What is the minimum diameter bold that you would trust?


http://i114.photobucket.com/albums/n267/DutchDude_2006/Moped_006L.jpg

 

[npk1977]

Interesting & fun idea. I'm not qualified to answer your question, but I can offer a solution: take the hub to a qualified machinist. I guess that you want your hole pattern to be concentric to the axle. A real machinist will be able to (1) drill a nice concentric hole-pattern and (2) give you some advice to tell you if the idea is stupid or not

'luck

 

[DutchDude]

Alright - I was thinking of drilling it myself - but just what do you think a machinest would charge for 9 holes in hub and sprocket (18 total)? Might be less of a headache, if it is reasonable...

 

[srdavo]

have a look at this hub adapter for ideas. they use ONLY six bolts
the adapter spaces the sprocket out for tire clearance issues.(occ stingray)
lots of pics.....the 6 hole pattern should work for your sprocket & hub.

http://cgi.ebay.com/Chopper-Motoriz...ryZ42314QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[japat100]

it is not only to drill holes ,,but you must have a way to center the sprocket and keep it centered ,in other words the holes alone with bolts will not keep it centered

, i place 8 3/16 bolts with lock nuts and made a adapter plate 1/4 thick to fit the small ridge on the hub ,and the other side made to fit the hole in the sprocket that would keep it centered .,, very time consuming to get it right ,, if you knew someone with a lathe that tinkers may get it done with little cost ,but i would not want to think how much it would be at machine shop charge by the hour ,but you could get a set price ,,
it worked out great for me because i have a lathe and plenty of time ,, and in my opinion a much better way to place sprocket then using the spoke system .. no broken spokes and my spokes are very small gage ,,,and the sprocket is very true ,,, may have about 300 miles on bike so far with no sign of problem

you may have a biggest problem and cost 10 times more if you change bike style ,,, did i hear you say the wife choose the bike

japat













japat

 

[DutchDude]

have a look at this hub adapter for ideas. they use ONLY six bolts
the adapter spaces the sprocket out for tire clearance issues.(occ stingray)
lots of pics.....the 6 hole pattern should work for your sprocket & hub.

http://cgi.ebay.com/Chopper-Motoriz...ryZ42314QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

I like that idea of the adapter - but that still has me drilling the same holes in the hub itself. I think I would be more comfortable with more holes then six. Doesn't the torque on a bold increase, the less holes you use? From just looking at it, and the amount of material available, it looks like you can fit between 8 and 10 bolds.

So, technically, it seems the only thing $65 would buy me is a hole pattern, that might, or might not center itself on the hub? And perhaps even an added problem of increased thickness/clearance. That money is probably best spend on a new wheel or hub, if I screw mine up

 

[DutchDude]

it is not only to drill holes ,,but you must have a way to center the sprocket and keep it centered ,in other words the holes alone with bolts will not keep it centered

I probably should figure out a way to drill the hole pattern in the sprocket first. Evenly, in a perfect circle, with perfect spacing Any suggestions there?

Then, I was hoping to be able to modify the dustcap with a dremel so that it would fit perfectly inside the sprocket hole? When I would hold down the dust cap, shouldn't it hold the sprocket in place long enough to drilll a perfect hole pattern through the sprocket?

 

[drimpact]

personally I would get a heavy duty rear wheal with 36 12guage spokes and not drill my sprocket.

Just my opinion, but having a concentrically mounted sprocket is absolutely positively necessary for smooth operation.

The hub also does not look very thick, you might have issues just bolting the sprocket onto it.

If this were my bike project I would look for the heavy duty wheel. Take it or leave it, It is only my opinion.

G'day

 

[japat100]

I probably should figure out a way to drill the hole pattern in the sprocket first. Evenly, in a perfect circle, with perfect spacing Any suggestions there?

Then, I was hoping to be able to modify the dustcap with a dremel so that it would fit perfectly inside the sprocket hole? When I would hold down the dust cap, shouldn't it hold the sprocket in place long enough to drilll a perfect hole pattern through the sprocket?

drill holes in sprocket first no problem ,, then place the sprocket over the hub no problem ,,, the trick part is that the sprocket must fit over the ridge part of the hub to be centered ,,, thats why you need adapter plate about 1/4 inch thick .. even if you could make the hole in the sprocket the right size to fit the small ridge on the hub it would still not work ,, because the spokes are about 1/8 sticking out of the hub that would be enough to keep the sprocket from seating flat against the hub ,,,and then the sprocket would be pressing against the spoke ends instead of seating flat against the hub

,the sprocket must press against the center of the hub to keep it centered ,,and thats the job for the adapter one side of the adapter fits tight against the center of the hub ,and the other side of the adapter fits the hole in the sprocket
not sure when you say dust cap what you mean ,,but as i understand you are going to keep the dust cap in place until you drill the holes ""no problem "", but bolts alone even if you get them perfect will not whole the sprocket centered on the hub for any length of time ,you may get a few miles out of it before it becomes off centered ,, only the adapter in my view will keep it centered
japat