DIY V1 mirage drive shafts

I've been wanting to experiment with different length pedal shafts (or cranks or whatever they're called). So, I got a pair of 15" 6061-T6 aluminum 3/4" bars (about $10 for the pair). That's about 2" longer than the stock length.

I decided to use 1/2" bike pedals, so I got the appropriate taps (a standard bike tool for cleaning up threads). I borrowed my neighbor's (tabletop) drill press and drilled 3/8" holes for the bolts on the bottom, 5/16" holes for the adjustment peg, and 29/64 holes for the pedals. It was fairly straightforward to tap the pedal holes, and I bought some cheapo pedals.

The right shaft is perfect. Unfortunately, I measured incorrectly on the left one, and the 5/16 hole didn't line up (metal is very unforgiving). I drilled it out a bit to get it to fit, so I can test it out. I'll post again once I get a chance to try it---with luck, that'll be within the next few days.

If I like the length, I'll redo the left one. In any case, I'll probably also test a couple other lengths. I think I've got the process down pat now, so additional ones should be a piece of cake (famous last words...).

Let me know if you have any questions.

Where did you buy the aluminum bars?

Wow that's awesome. I have a pair of 7075 aluminum bars, to be drilled, could you help me? Also, are you going to get them anodized?

                                                                                                                             Wow….

Might be a stupid question but what is the advantage to the longer solid stock?  Stronger?  Is more leverage going to expose a weak link somewhere else down the line? 

Where did you buy the aluminum bars?

I got the aluminum at "Gorilla Metals" in Santa Clara, near the SJ airport:
http://www.gorillametals.com/
I've gotten metal from them a few times now and they've always been very professional. For small stuff like this, you can usually just drop in and they'll cut it  then and there.

Might be a stupid question but what is the advantage to the longer solid stock?  Stronger?  Is more leverage going to expose a weak link somewhere else down the line?

I usually use the number 6 setting for the pedals, but I like to also use 7 once in a while. When I put it at 7, my heel tends to just barely bump on the boat before the pedals bottom out. So, that's what got me thinking that longer cranks might be useful. In looking online, I found one guy who'd made 15" arms and liked them, so that sounded like a good starting point. If there's more leverage, that's just an added bonus. Due to the failure issues with the hollow cranks, I figure that longer ones should definitely be solid. And besides, solid bar is much easier to find.

Wow that's awesome. I have a pair of 7075 aluminum bars, to be drilled, could you help me? Also, are you going to get them anodized?

One concern is that cutting the threads in 7075 might be pushing the limits of the taps I have. They are actually not designed to cut fresh threads, just to "chase" threads in bike cranks. If I had it to do over again, I'd get the 1/2 x 20 taps from, say, McMaster-Carr (they do have both right-hand and left-hand threaded versions), instead of the Park Tool version. They are about the same price.

Let me do another set first, just to make sure I've got the process down. Unfortunately, it might be a while before I get to it, since I've got a never-ending deck project that keeps interfering with all of my fun...

We've got to talk because this might be the solution to my issue.

And I'm just 10 minutes from the airport.  Thanks so much for posting this!

I want a pair!!

We've got to talk because this might be the solution to my issue.

Which of the myriad of your issues are you talking about?

We've got to talk because this might be the solution to my issue.

Which of the myriad of your issues are you talking about?

I'll get pictures this weekend but basically the long bolt that goes through the shaft and then the pedal pulled through the shaft.  I know that doesn't exactly paint a clear picture but it's the best I can do.  Pictures will help.

By extending the bars, doesn't it mean you'll have to raise your legs up even higher? With the factory bars, the sitting position makes my butt sore after an hour or so because it puts too much pressure on my ass. I think it would be even worst if my legs need to be raised another 3-4 inches while pedaling.

By extending the bars, doesn't it mean you'll have to raise your legs up even higher? With the factory bars, the sitting position makes my butt sore after an hour or so because it puts too much pressure on my ass. I think it would be even worst if my legs need to be raised another 3-4 inches while pedaling.

I owned a recumbent bike for several years and we called that "recumbent butt". It seems to come with the territory.

Among recumbent bikers, the ideal butt-to-pedals angle is a very personal thing. Some recumbent riders have pedals that are above head-height which puts more of the weight on the back, and thus (they claim) offers some relief to the butt. On the other hand (or is it "cheek"?), some riders want the pedals well below butt-height. By those standards, a couple of inches is small potatoes, but I'm hoping that longer equals slightly more heel clearance and it will certainly give a little more leverage and a slightly longer throw. And besides, it's a fun thing to experiment with.

I plan to make at least one more pair of cranks (gotta make use of those taps...). When I get to that, I'll try to remember to make a video. There are a couple of small points (hard to explain, but easy when you see them), that will probably make it go a lot smoother if you decide to give it a go.

Bike cranks are offered in different lengths to suit different body types. Short and medium riders generally have a shorter crank while tall long legged riders have longer ones. This option allows the leg/knee to obtain a comfortable crank revolution and power efficiency with each pedal turn. Hobie has a one size fits all and uses seat adjustment and their one through seven pedal shaft adjustment system to accommodate different body types. This works for most of us but I can really see the point of the tall guys needing a bit more pedal shaft length to increase comfort and efficiency. With increased length comes greater leverage and torque so solid shafts are a must. Glad to see the experimental upgrades coming out of this group.