ak47clown

Hey all-

First post here...

I recently got into road cycling after the urge to try something different. I've only been riding on and off since October (lately not as much) but did pickup a used kurt kinetic road machine off craigslist and plan on sticking primarily to indoor training this winter. I like the trainer a lot but after seeing the Rock n' roll addon for it, it got me thinking why couldn't i do something like this?

After a quick search, I came across a short clip of someone who apparently had a similar idea:
https://cozybeehive.blogspot.com/2008...r-trainer.html
and:
https://www.youtube.com/watch?v=u5CtNT2KEa8

I've tried emailing the guy but his mailbox is full. I even went as far to email general info for the website he works for with no avail. It doesn't look like this went any further than a concept but looks fairly easy to do with minimal parts to buy.

From what I gather, He's got the board resting on a couple of U-bolts to provide the smooth side to side movement and then attached a few springs for resistance. It's hard to tell how many or where they are located but it seems like they are probably towards the middle and my guess would be 4 total springs. Other than some way to secure the trainer to the top of this platform, that seems to be the extent of it.

I'm a big hands on person and think this would be a great project to take on if nothing else but for the experience. However, I would like to try and give it some realistic resistance so that I'm not stuggling to stay balanced in the center or fighting with the bike to try and move side to side and I've got no idea where to start in terms of figuring out just what sort of compression springs i should use or if there's even a better method. Mcmaster.com has tons of springs to choose from.

I've thought about some improvements that could be made to this design as well-
-perhaps using ball bearings on a central shaft vs. resting the platform on U bolts. However, i think for the simplicity and relatively small amount of movement side to side, I don't know if there would be a major advantage

-Also, I've been thinking that perhaps using gas struts would provide
a potentially stronger and more rigid yet still realistic platform. This could also be potentially cheaper than the springs depending on what amount of force is necessary...

What I could use some help in is determining first of all how to even go about estimating the forces (centripetal?) that are induced in cycling and then how they can be recreated using either of the methods listed above. Any good mechies out there care to chime in? Any help/advice would be appreciated!

CyclingBee

Howdy.

Hmm..You may start the analysis like this. Take some 2 by 4's, wide enough to cover the basal area of trainer. Place a bathroom scale (or any better one) under the planks. Set your rear tire into trainer and place the trainer onto the planks in such a way as to not jam the weighing mechanism. Get another block of height equal to the height of the plank and the scale and place under the front wheel. Now mount the bike and ask a friend to find out what the scale is reading in the rear. You can try placing the scales on either side of the trainer. This way you'll atleast get a rough number for the moment (torque) that your springs should be supporting in order to resist pivoting motion when seated.

-Ron

Kimmo

Why not just learn to use rollers?

ak47clown

Hey cycling bee-funny seeing you here

I'll take some weight measurements today and am gonna talk to a few engineers at work to see if we can come up with anything.

Kimmo-it's not that i don't want to learn how to use rollers-I made the investment in the kurt kinetic trainer after reading a good deal on the difference between the two types of trainers out there. My conclusion was that with my price range, i could either buy a top end, highly rated stationary trainer or a low to mid level set of rollers. The big thing that pushed me towards the fluid trainer was the resistance that i get with it. Now all I'm trying to do is take it to the next level

jsharr

Go to the road bike forums and seach there. Lots of roadies have built platforms for their trainers.

CyclingBee

Sweet. Good luck and let us know.

-Ron

ak47clown

hey jsharr-are you talking about the road bike section of these forums? I couldn't really find any mention of it...

Kimmo

Hm, wonder if you could graft the resistance unit onto a set of rollers...?

Haven't looked into using trainers myself, so I'm surprised to hear something as simple as a set of rollers is more expensive than the resistance type, with all their fancy means of creating drag...

ak47clown

yeah...a good set of rollers can run as high as 700+ I have actually seen some mag resistance rollers out there but my primary concern for training this winter was to mainly improve my aerobic base. Now if i can add some side to side motion to that-it would only be a plus. Also, practically speaking, I wouldn't want to go through the trouble of trying to sell my trainer now to purchase a set of rollers.

jsharr

yes, and there are tons of threads if the search function is working.

https://www.bikeforums.net/showthread...motion+rollers

https://www.bikeforums.net/showthread...motion+rollers

https://www.bikeforums.net/showthread...motion+rollers

I just searched for 'free motion rollers" and got tons of hits. Above are just a sampling.

mconlonx

Whatever you decide to cobble together on your own, please make sure you do one critical thing:

Video yourself on your first attempt trying it out.

Please?

jsharr

Okay, I misunderstood what you were trying to do. I was thinking of free motion rollers and you are wanting to build an articulated platform for a trainer. I am wondering if you could adapt skateboard trucks to do this? Skateboard trucks in center, inline, between two half sheets of plywood, and maybe nerf footballs sandwiches at each side? cut the balls to fit until you get a range of motion you like.

Cyclist01012

If you want the feeling of riding outside, why not ride outside?

Steev

Because the roads are covered in snow and it cold out there.

ak47clown

Yeah definitely wasn't looking to make myself a set of rollers but the skateboard truck thing is an idea- essentially that looks like what the Kurt kinetic unit is with large rubber bushings. I've got a number of reasons for not wanting to ride outside but mainly I just don't feel like subjecting myself to the cold when I can get a perfectly good workout inside!

Cyclist01012

And thats a bad thing?

cyclist2000

Trial and error is a really bad and expensive way to design something. Start with a simple diagram and some simple force calculations will determine the spring loads.

ak47clown

if you have no desire to ride in those conditions, then yes.

Anyways-as luck would have it we had some extra gas shocks that are just about the perfect size kicking around. They're rated at 70lbs which i'm guessing might be a little light but at least it'll give me a starting point. Apparently there's some adjustable ones as well which would be even better. After talking over the options wtih a few people, i think the gas struts are the way to go.

SpeedyChix

The Training Deck is an interesting piece. I ended up buying one from him as the parts / welding cost were higher than getting a built one from him. If any of you want pics of it or would like me to ship it to you ... that can be arranged. I've been riding outside as much as I can so it's not seeing much use. At present the clamps are setup to hold a CycleOps roller. If you're used to riding a 'fixed' stationary bike, this does make a nice diversion from that and the opportunity to work on improving balance as well.

Just noticed this finally posted almost a year later. Oh well. Details are the same.

Drtumolo

Does anyone have plans or some good pictures of this deck?

SpeedyChix

Sent you a message (via your profile page). Character count allowed is quite short using that.

pics here if others are interested in seeing a built one.