DIY V1 mirage drive shafts

I've made a second set of crank arms. I did things a little different this time, and I think I've got the process pretty much dialed in. IMHO, the secret is to make a template instead of trying to measure things directly on the aluminum bars. A template makes it easy to get consistent results, things go a lot faster (once the template is done, that is), and mistakes are a less costly (and less frustrating). Best of all, I believe I've found the ideal template material. An aluminum channel is available that is 1" wide with 1/8" thick walls and square corners. So, it's exactly 3/4" inside the channel and it slides over the aluminum bar, with only an infinitesimal amount of play. This is the stuff:

http://www.metalsdepot.com/products/alum2.phtml?page=6063%20aluminum%20channel&LimAcc=%20&aident=

I think the "C31-1218" is what I've got. A 6" strip is all that's needed but it took me 3 tries before I got it right. The measurements need to be dead on---the spacings are given on the attached pdf.

I've also attached a couple of pictures of the template and the finished crank arms. Note that the adjustment pin is centered in the plastic hole. Also, both crank arms are identical, except, of course, for the left-hand threads vs right-hand threads for the pedals.

Unfortunately, I still haven't had a chance to try them out, but will report back when I do. However, it's looking like that might not happen until rockfish season opens.

Looks really good. I'm sure you will happy with the water performance. A template for the bottom two holes is the smart way to go. The pedal holes are not as critical except for needing to be dead center in the solid aluminum shaft.

I've added a couple of drill bits to my arsenal and I think I can now make these semi-efficiently. So, I'd be glad to make a few sets of V1-like crank arms for NCKA'ers who might want to try something different.

If there is interest, I'd like to do them all at once, since that will take way less time than doing them separately. I can pick up the metal bars (6061-T6 aluminum), and I'd drill and tap them for you. You'd still have to do a little filing (bottom corners need to be slightly angled, and the ends might be a bit rough), clean/polish, and add pedals. Note that I've only got taps for 1/2" pedals, so you'd want to be sure you can find pedals you like in that size.

I'm not looking to make any money, so no charge for my time---you'd just pay for the cost of the metal bars (roughly, $10). For me, it's more like a science project to see how they hold up over time. PM me if you're interested, and let me know what you have in mind. I'll probably only have the drill press for a few more days, so this will have to happen soon.

PM sent.

Can you do 7075 aluminum?

Really like them and wish I could get 3-4 pairs    Thanks for the post!

Great subject. ...And another point. ...CLIP IN BIKE PEDALS.  I am sure for those who spend more than average time on the water clip in shoes and pedals will be an excellent advantage. They make for cyclist warm weather sandal type shoes that can clip in. Go online and check out the shoes and pedals. The fit with the stock Mirage drive pedals is not perfect...and bit sloppy, depending on what type of shoes one wears. With a soft sole dive bootie one can get sore bottom of the feet. Clip in bike sandals would fit great, with or without socks.
   And good point about changing the length of stroke on the Mirage drive....throughout the day. I have spent 6 hours straight on the ocean....have had sore butt, so I changed the length of stroke and that helped.
   The length of the arms was covered well by Charles. Not sure if a longer length would be good for me...5ft 9in. Taller persons I guess could use a longer length of arm...or at least try.
   Keep the ideas coming in! Thanks, Ron

I finally got a chance to try them out today. I gave my 15" cranks a decent workout, pedaling from the Santa Cruz harbor almost to the Capitola wharf and back, mostly at a slow trolling speed. I don't have the exact distance, but I'm sure it was at least 3 miles each way. I made a brief (really boring) video:

https://www.youtube.com/watch?v=qKPlxKWahZ4&feature=youtu.be

For the last half mile or so, I went faster---not all out, but as fast as I figure I could expect to maintain over a substantial distance.

I definitely like the crank arms and have no plans to switch back to the stock setup. In fact, I might experiment with even longer ones just to try to dial it in. My (completely subjective) impression is that the added length makes for slightly more efficient pedaling and it also seems to take a little pressure off the butt. Another positive is that the bike pedals reduced the tendency of my feet to slip as compared to the Hobie platform/pedals, in spite of the added length.

I didn't notice any real negative, but based on my recumbent biking experience, I'd expect that moving the feet up can cause toes to go numb more easily. I always get a little of that when I troll for long periods without a break, and it didn't seem any worse (or better) than usual.

Note: I changed the link to a slightly better version of the video. For some reason, the original video was especially blurry.

RAP - I see where you're going with the clip in pedals (which are strangely called "clip less" pedals), but I think that is a VERY bad idea.

How many times have you seen a novice cyclist topple over at a stoplight with both feet stuck to his pedals? It's funny (and only mildly painful) on a bike, but could be a SERIOUS problem on the water. Add in some saltwater exposure and corrosion to your clipless mechanisms, and you could be in serious trouble if things go south.

Probably not an issue for people who are experienced with clipless pedals (I like the Eggbeaters, myself), but probably a bad idea for people who don't spend much time on a bike.

$10 FOR A SET? I will give you $20 for a set as a PIF for your efforts! A little longer than stock length suits me as I am 6'4" and sport extra ballast leeward

Not to be a shit disturber but if you are going to get any warranty work done on your drive, switch back to the stock length LOL.

Just a quick update, as I've been out several more times with these 15" crank arms---the last 3 times in less than ideal conditions. I still like the mod a lot and there's been no down side. When time permits, I'll experiment with slightly longer lengths, like 16" and 17". I'm betting that 16" will be optimal.

Yesterday, I was going to remove the crank arms for some routine maintenance. The left one came off without a hitch, but the right one was another story. The stainless bolt that holds the arm onto the drum would not budge. I used a fair bit of force, but didn't go all out, since I don't want to damage the plastic drum. I'm guessing there must be some slight galvanic corrosion, although it is strange that the other side looks good as new. Anyways, it still works fine, so I'm going to wait until the off season before I use more serious force to separate it.

So, if you're using solid aluminum crank arms, I'd strongly suggest that you liberally grease the area where the SS bolt passe thru. Even with that, it would probably be a good idea to remove the bolt regularly to check that no problem is developing.

A true kayak fisherman. If there is a problem we will figure out how to fix it before the manufacturer does.
Good work on the write up. You're quickly becoming a superstar on the forums with the Salmon video's and tutorials.  . Thanks for sharing.

A true kayak fisherman. If there is a problem we will figure out how to fix it before the manufacturer does.
Good work on the write up. You're quickly becoming a superstar on the forums with the Salmon video's and tutorials.  . Thanks for sharing.

Thanks, but I've only got 2 salmon so far. Hopefully, it'll become a habit...

Btw, it seems that for 2015 Hobie will use hollow crank arms, but with thicker walls than previously. I suspect that'll solve the breakage issue.

Another quick update...

I took the troublesome crank to a bike shop and got the one stubborn bolt removed. Then I took the whole mirage drive apart, cleaned and greased everything and put it all back together. There was a little bit of surface rust on the pedals (they are just a cheap $10 variety), but everything else looks good as new. That's pretty much all there is to say for season 1 on these crank arms. I'm expecting to get many years of service out of them.

For next season, I think I'm going to try spacing the pedals a little farther apart---more like a real bike. I guess I can't help but tinker with it... Anyways, I'll let you know how that goes.