Rollers, Resistance with earth magnets

Bozabyka

I would like to create more resistance to a set of Minoura Action Rollers.
Found a unit to buy but realise I can achieve the same using earth magnets.

http://www.bikeforums.net/road-cycling/ ... llers.html

I would like to use these
http://www.ebay.co.uk/itm/20Pcs-Strong- ... SwyQtVjkWb

Think I can make a neater job with round disc type magnets then put the discs on to a threaded bar and place onto predrilled holes on the rollers which are there for shorter wheel base bikes.

if I have a load of disc type magnets together I have created a cylinder.
I now want to create resistance on the roller drum will the magnet be pushing or pulling?
Is there a reason I would need to use flat magnets?

sungod

presumably it's an aluminium roller, the magnetic field needs to point 'into' the aluminium, north/south doesn't matter

the resulting braking effect is caused by eddy currents induced in the roller by the strong magnetic field, bear in mind this will also generate heat

if i'm interpreting you correctly, those disc magnets on a rod are not going to do what you want as the field axis will run along the rod

Stephen R

Hi, I have the Jet Black rollers with aluminium drums. I made my own resistance unit from 8 20mm diameter Neodymium magnets (similar to yours but not drilled) These are taped to a length of wood of similar length to the rear roller. The flat disc of the magnets face the roller. The wood is hinged to the roller frame and can be adjusted so that the magnets are within 1mm of the roller. The resistance that this provides is BRUTAL! I added a gear cable/cable housing and a lever so that I can control the resistance from the riding position. Don't have a power meter yet but just do intervals resistance on for 3 min/off for 3min etc. Let me know if you want pics/video. The magnets can be taped to the wood; they are not attracted to the aluminium roller so you won't need anything other than duct tape, or you could glue them on.

Here are the magnets: http://www.first4magnets.com/circular-disc-rod-magnets-c34/20mm-dia-x-3mm-thick-n35-neodymium-magnet-3-6kg-pull-p6199#ps_1-6759

Bozabyka

Hi Stephen,
Pictures and video would be great to see
Thanks