Dynamo fitting

[Daddybus]

I bought this miller dynamo set from eBay & I'm trying to set it up with no instructions ....is this the correct angle? It seems to be quite noisy & draggy - also it doesn't work yet! There appears to be a small hole in the bracket for a screw? (Which I don't have) is there another wire from the terminal to this screw? Cheers

 

[raleighnut]

You need to set it up so that the drive wheel rubs on the tyre parallel to it (as close as possible) to minimise drag.
As for the electrics most use the frame as an earth/return so a wire needs to run from the dynamo to some bare metal on the bike frame to allow the front to have a connection but the rear should work as it is (bare metal on the bracket)

 

[biggs682]

@Daddybus the one i removed yesterday just had a grub screw in that hole with no earth wire

and they are always fairly draggy and not very bright

 

[midlife]

It needs to be higher up and a little further in to end up parallel, the small hole in the bracket is for a sharp grub screw that locks the bracket into the frame to stop it moving,

Shaun

 

[Daddybus]

If I put it any closer the rear light faces into the wheel .. That's why I put it where it is I guess the bracket for the light may be bent (with a bad bulb maybe- can you still get them for these old ones?)

 

[Bobtoo]

The grub screw is to provide a return for the front light. The rear already has a return as it's on the same bracket. In my experience the power from the dynamo is more than the rear bulb can handle on its own, so the rear bulb will blow if the front light isn't working.

Edit- in the absence of a grub screw you can run a wire from the dynamo bracket to something like the rack mounting. That should make the front light burst into life. I think you have probably blown the rear bulb, you should be able to get a replacement at a good old-fashioned ironmonger or there's always eBay. The screw fitting on the bulbs is fairly standard and the specs should printed on the bulb.

 

[raleighnut]

If I put it any closer the rear light faces into the wheel .. That's why I put it where it is I guess the bracket for the light may be bent (with a bad bulb maybe- can you still get them for these old ones?)

It doesn't need to be any closer, it needs rotating on the bolt so that the wheel runs parallel to the tyre. The brake arm may stop you getting it perfect.

 

[Bobtoo]

If you line the dynamo body up with the wheel axle that will give you the correct angle. You might have to move the bracket on the stay a bit to get it right.

 

[tyred]

Personally I'd wire it with 2 wires and not use the frame as an earth as it'll work better and be more reliable. Speaker wire is a neat solution for this and cheaply available from any hi-fi or car accessory shop.

Take a straight edge and hold it parallel to the axle of the dynamo (running through the roller straight down the dynamo body) and see if it bisects the axle on the wheel. If not, adjust until it does. The tail lamp bracket can be bent to point in the right direction afterwards.

You only need just enough pressure against the tyre to drive the thing, any more will increase drag, noise and tyre wear. if you have a ~3/8" gap when the dynamo is off, it should probably be okay.

SJS cycles will have rubber caps which fit most bottle dynamos and it will run quieter and be less likely to slip in the rain with one of those fitted but it isn't strictly necessary.

 

[Daddybus]

Thanks for all the replies I've managed to get it running more parallel to the tyre ...not as draggy but still noisy- I've fitted a grub screw (of sorts) but still no lights.... On further investigation the rear bulb is blown I think... Its blackened (its the original! miller 6v .1a ) the front bulbs look like new- the light is a nos miller with no signs of use at all with the original silver wire so I'm giving up with the blydy thing... I hardly ever ride at night anyway haha

 

[raleighnut]

Just run a return wire (wrapped around the feed wire) back to the bolt and replace the rear bulb, jobs a good un.
They do get quieter with a few miles on em.

 

[Daddybus]

Forgive my ignorance ... Are we talking a wire from the terminal on the body of the front light to the dynamo bracket bolt / grub screw??

 

[steveindenmark]

I think they are always noisy and draggy, which is why I use hub dynamos.

 

[Paulus]

Bottle dynamo's are always slightly noisy and because they are sprung loaded onto the tyre will always be a bit draggy.

 

[raleighnut]

Forgive my ignorance ... Are we talking a wire from the terminal on the body of the front light to the dynamo bracket bolt / grub screw??

Yep.