Increasing resistance on SportCrafters Overdrive Rollers

hmar

Hello,

I have owned my overdrive rollers for a couple of years now and I absolutely love them. However, I am living abroad now and I am thinking of pairing down my bikes to just my mountain bike (29er), which means that my MTB would also be my bike for my rollers. My largest chainring is 36t (I could perhaps gear up to 38t) and my current cassette is 11-42. As a consequence my gearing will be smaller relative to my road bike.

I am wondering what my options my be for getting further resistance? For instance, has anyone managed to rig up a Kreitler Heandwind unit to non-Kreitler rollers such as the SportCrafters?

On a similar note, I am wondering what is the impact of tire width on the resistance felt by the rider on the rollers? For instance, by running a wider but smooth 29er tire (perhaps with lower pressure), will I be increasing my resistance relative to the 700x23c tires I've been using with my road bike?

Thank you in advance for any assistance that you can provide.

Harry182

Try running two resistance drums?* iirc - you can buy spare resistance drums on Sportcrafter’s website.

Also, in my experience, tire pressure greatly affects resistance on the rollers - I use the Planet-X badged version of your rollers and always pump my 23c tires to 100-psi before every workout to keep things consistent. If I’m even a few psi lower I definitely feel it and can’t maintain the same rpms/speed.

* - I have no idea if this will actually work.

redjeepǃ

There's been a bit of a cottage industry online on this. The resistance on any metal cylinder rollers can be increased with a few magnets positioned close to the rollers.

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

It seems pretty effective and not too hard to do.

chaymck

I find the resistance roller pretty good. I only use hr but they are plenty strong enough for LTHR sessions.

Running 25mm, at 90 psi.

capt_slog

hmar wrote:

Thank you in advance for any resistance that you can provide.

Fixed that for you.

As has been said, lowering tyre pressure will make a difference, I've found it makes a LOT of difference. When we first started (son and I) messing about with our homemade rollers, we adjusted all sorts of things to get both our bikes to work nicely. It turned out to be tyre pressure causing the differences, and not the roller spacing as we first thought. I've now scrapped the homemade ones, and bought a set of Tacx.

The magnets idea also sounds good. I've considered fixing an aluminium rotor to one of the tacx rollers to give around 25mm extra radius, and then having that rotor run through a couple of closely spaced magnets.

The magnets induce eddy currents in the aluminium (it has to be non-ferrous) and these cause a braking effect, a sort of friction-less friction. Also causes the aluminium to heat up, I'm not sure how much or if it will get too hot.