CliffordK

The OP started off saying that he wanted to build something.

I assumed he was planning on doing some welding (or in this case having some welding done). I wasn't expecting him to be making an exercise bike out of bubble gum and duct tape MacGyver Style.

An exercise bike doesn't have to weigh 10 pounds.
It doesn't have to be pretty. It doesn't have to have pretty welds.

It just has to be functional.

One doesn't have to be a Master Welder.

If he is a "Junior Rider", then he may have access to tools and equipment through his family, or some schools have far better equipped school shops than any home shop ever has. And, with some luck, he can be on the good side of a shop teacher.

What better bike for one's first bike build than a Stationary Bike. And no need to worry about a fork breaking on a break-neck curve.

Can a racer weld a bike?
In fact, Eugène Christophe got his first experience of welding a bike back together in the middle of a leg in the Tour de France.

Starting with a Junker Bike/Frame... one can get the dimensions and angles for the seat tube and handlebars correct, and mostly fit to the rider. And, have 3/4 of the parts for the build.

Or, a used stationary bike might also be a good donor for such a project, with its strengths.

And yes...
I have built a ridable "Franken-Bike" out parts that never were intended to be together, and some weren't intended to be part of a bicycle. And, while roughly of the form of other bikes... it looks like no other bike in the world.

My next bike will probably be scratch built, but the Franken-Bike was certainly a learning experience, and good practice. And, I'll use what I learned on it, and from riding it for the next bike of a similar style.

carleton

I asked him directly and he answered directly. He needs a training tool, not a project.

Quinn8it

@Zero Talent
ive got a Kurt Mag if Ya want it

carleton

+1 Very generous of you.

That's what I'm using these days...till I can save my pennies for another Cycleops (had to sell my old one. Too heavy to move across the country).

If you get that, Zero. But, a Conti trainer tire. That will both increase the traction and save your tires. Totally worth it. I've been using the same trainer tire since 2009 and it stays grippy up to around 2000W.

CliffordK

Yeah?
Isn't that why one would build a "Trainer"? For training?
If one wants one out of the box, then go down to one's favorite Dept Store and buy one.

If one wants something unique and functional, then build it.

Here's a bit better photo of the bike (still from the right side).
https://www.flickr.com/photos/tim-eat/7971809202/

You could do all the CAD stuff to get the 3rd sprocket on there.

You could also either run the 3rd sprocket on the inside of the crank like a "triple". Or, build it out of Tandem parts with both right and left sided chainrings. There have been people who have drilled old Campy Strada (or Dura Ace?) flat cranks to mount triple sprockets on the inside. Or, you could cut the crank arms off and bolt the 3rd sprocket to the outside of the spider.

Getting the right size (gear ratios) will be a pain. I don't believe there are any stock MTB sprockets that size, so either re-purpose something like a rear BMX sprocket, or compensate elsewhere in the design with larger sprockets throughout, and possibly a heavier wheel.

I can only guess on the number of teeth on each of the sprockets, although if Quinn8it actually has one of the bikes, he could take a bunch of high-res photos, measurements, and etc.

But, if you want it to be unique, then hunt for ideas, but make your own build.

There is a $150 Velo Cheap Contest. Perhaps I should build one of those exercise bikes for less than $150, then take Carleton's $25 to apply towards freight/postage It probably wouldn't have the same boxy shape as the original, but it would get most of the basic design elements.

Zero Talent

Thanks Quinn. I already have a kurt type trainer, the nice cycleops. But that is very generous. This isn't an extremely urgent project as I have rollers and a trainer I just something I have been thinking about for a while and it seems like it would provide more resistance and better feel. Thanks so much though.

Quinn8it

The gearing is not that complicated

i currently have a 48x16 on the rear drive, connected to a standard 53/39, then to a 10speed cassette.. Probably something very standard 12/27 or similar.. Road drive is shimano 105.. Downtube shifters mounted on the top of the frame.

CliffordK

Ahhh... here you are:
16 Tooth Chainrings

Oops, you may have to settle for 17T. Hmmm... lists 16 under the quad, and 17 under the triple listing, but the splines look the same.

Take a Campy Strada (or similar) crank.
Cut the arms off.
Bolt this to the outside of the spider.

And you've got your front idler mostly built.

Quinn8it

You are on the right track..

Although getting Predator to sell you the little piece that fits on the rotor spider and threads on a track cog would be a lot easier

Zero Talent

Thanks so much guys, I'll show this to my Dad tonight he is really excited about this project.

carleton

Let me know where to send the $25...if this ever happens

I got money saying it won't.

slindell

An easier project might be something like the BT trainer - similar concept to the Lemond where you replace the rear wheel and use gearing to spin a fan behind you. Seems like taking the rear triangle off another bike would give the framework and shifting if you want to use a track bike on the front then just put fan blades on the rear wheel of the donor bike. Trying to find a large cog or narrow freewheel on the other side of a flip flop hub is a problem - it looks like white industries uses the same interface for their cogs and cranks so a fixed/free hub from them might support a chain ring on the fixed side (check with them first). On a geared bike you could put a 42 tooth cog on the inside to drive the rear chain. I thought about doing the project for something to play with but decide the time was better spent training.

BT Advanced Training System | Bike Technologies
42 Tooth Cog for 10 Speed from OneUp - NSMB.com
SINGLE SPEED RINGS ? White Industries

CliffordK

You could use the fan assembly off of a used Schwinn Airdyne, or similar exercise bike, and only need to build the connection between the trainer and your bike. However, the point of the ErgoBike is that you may be ok with just using a wheel (weighted?) and not a fan.

This would use your racer or trainer bicycle which has both risks and benefits.

Quinn8it

slindell

That is it, you could keep the derailleur from the donor if you want to move the shifting to the trainer. You can use a cheap used bike on the front if your real bike is not desired. The nice thing about the Predator is moving the wheel to the front to keep the size down and removing the rear triangle flex.
Reasons to do this would be you want a project, you want to connect to a bike that otherwise would not work on a direct drive trainer (track bike) or you have special needs for resistance or momentum.
Downsides are that the whole thing would be just slightly shorter than a freight train and if using a road bike a Lemond trainer can be found used for 300-400$ so might be cheaper if you have to pay someone to weld.

CliffordK

Or... perhaps the Cycleops Silencer.
New Cyclops Silencer 9800 Trainer w Cassette | eBay

Perhaps you could find one to try out and see if you like it.

Quinn8it

Once you have gone Wind Resistance- there is no going back!

carleton

Would you say that I'd be [puts on sunglasses] blown away?

Quinn8it

Id say that if you spent some time on the predator ergo- you at the very least would put it near the top of the list of trainer options- even if it is pricey and obscure...

The US team a Predator and a Watt-Bike at ADT, and for everything except standing starts most people preferred the Predator

carleton

Any update on this?