If anyone here has put together a DIY version for free motion rollers, I have a question.

I am close to finishing my version to accommodate my Kreitler Rollers with the Killer Headwind. This involves building a wooden chassis that the Kreitler's drop into (didn't want to directly modify the Kreitlers in case I wanted to use them the old way), and the chassis has the rollerblade wheels that in turn sit on top of some 1"x6"x10' boards.

I do not want to cut these boards until I know how much runout I will need for the motion itself. I am using 24" bungee cords and I will attach them in a "V" with the 2 points being on the wooden chassis and the point of the "V" on the crossmember of the track below. The reason this is important to me is because I plan on the left underside track being a few feet longer than the right, to accommodate the movement fore and aft of the Killer Headwind unit.

So my question for anyone who has done a DIY free motion project is, how much lateral position did you find worked best for the attachment points of the bungee cords, i.e., 1 foot on both sides, 6 inches?

I haven't used the free motion rollers. I'm just responding to say that you're question might get better attention/responses in the ROAD CYCLING forum. I'd think rollers in general are more of a 'roadie' think. Not sure as many roadies come into the general forum.

Dan

Not sure I understand the question,

but I had shock cord attached to the front corners of the rollers, forming a v to a hook in the middle of the plywood base,

and the same for the rear. The two hooks were about a foot apart, & allowed ~4-6" for/aft travel.

You could leave the pieces long & trim after using it for a while.

Thanks, woodcraft. That's the kind of data I was looking for. I have a "V" too for the bungees and bought 24" versions. I would like to minimize the footprint of the under the rollers platform and a 24" bungee in a "V" will provide way more than 4-6" of fore/aft travel.

Think I will try 12" or 18" bungees and see what that creates.

Different diameters of bulk shock cord are available at fabric, hardware stores, or online.

make loop at the end by wrapping with wire.

Then the travel & resistance can be adjusted by the size, length, & number of bands.

My implementation has hit a snag. I was testing the fore/aft repetitive motion of my chassis (6 inches forward/backward) and slowly the chassis creeps from centerline. I thought maybe some of the rollerblade wheels had a bias or a toe-in as to how they were mounting, but I haven't been able to diagnose the problem.

I have seen some builds with rails included to keep the wheels in track, but other builds without. Seems that working with dimensional lumber (2x3s) there's always the chance of introducing a bias.

I've been debating building a stand and free motion retrofit from dimensional lumber so post back or let me know what you find out...
Maybe a vertical 2x3 and a set of roller blade wheels on the horizontal plane to hit the 'wall'?

I still have a few bugs to work out. I found that without restraint the carriage will bias off centerline fore/aft. So, I need some furring strips or what I am trying some halved pvc conduit for the wheels to ride in. Unfortunately, I am dealing with some additional friction which may be caused by interference between the tracks and the moving carriage. If I have to, I will try the furring strips.

My cradle has eyebolts spaced 1 foot apart at both ends of the carriage and I have attached 18" bungees to centerpoints on the cross members about 1 foot away. I used rubber insulated electrical straps to secure the "V" apex of the bungees.

Here is my completed project. Even though I have been on rollers for many years, I am not sure how I feel about standing up on these. Seems between, cradle, bicycle and me, there's a lot of weight being handled by those bungee cords.

[IMG][/IMG]

See , adding roller blade wheels at the edges of the rollers, to keep you from coming off the ends.

guess time will tell if the 2 on the front are sufficient..

Not sure I understand as I have those at the front?

ends of front roller

I believe you misunderstand my concern. Not worried about side-to-side, lateral drifting. Yes, I have the front bumpers for that. My concern is that the bungees are not strong enough to maintain control of the rollers when I stand up.

Even though I have ridden the Kreitlers for over 30 years and can take my hand off to get the water bottle, I had never considered standing up and with the DIY Freemotion rollers I still cannot get myself to try.

I guess my concern relates to the variability of the home-brew versions; strength, length and number of bungees, rolling friction of the rollerblade or skateboard wheels, total weight being carried, etc.

Robert Forstemann could barely take on a toaster,

so you will probably not overpower a couple of bungie cords.


Congrats on your project, & good luck with the advanced skills.

I'm not sure I understand your concern. Are you worried about snapping the bungie cords or about the wheels/rollers getting angled? Perhaps add another set of bungies, or add a frame so the moving bit stays straight?

The 8 wheels roll in 16in. tracks made of halved conduit piping. I am just concerned for that first stand out of the saddle. Not sure what to suspect.

Just go for it. what's the worst that can happen?

I ride off the front of the rollers, just as I might have had I tried to stand up the last 30+ years?

Plenty of people are able to ride out of the saddle on fixed rollers. Standing is actually the easy part. Sitting back down is where you have to be careful.

This just came in. I thought it fit.
Capture.JPG

Here is my finished implementation. 2nd photo shows how I tightened the screw eyes on the carriage flush and added twin 18 inch bungee cords in pairs on both ends. The bungees I added are in a higher plane so, in theory, they lift the carriage some reducing friction downforce on the wheels. Seems to help. The lower bungee is secured by an electrical, rubber insulated, strap with an additional small pipe strap over the top for additional security.

The carriage concept keeps me from needing to modify my Kreitlers and the Killer Headwind comes along for the ride as I added a stop to their out front angle so that the hover above the base. Also, if I want to move the chassis and base out of the way, I can still use the Kreitlers with my Kreitler fork stand. The downside is the additional weight of the chassis construction, hence the need for additional bungee cords.

[IMG]IMG_1413 by gkamieneski, on Flickr[/IMG]

[IMG]IMG_1417 by gkamieneski, on Flickr[/IMG]