Rock solid Hobie drive arm upgrade group buy ... UPDATED WITH ORDER INFO!!

Is there a video or instructions about to change this part?

Not yet .... But that is a good idea. I'll work on getting one made up. It is a super simple part to change out.
Just unbolt the old arm and pedal, remove the 'click and go' adjustment and reattach parts to the new arm and bolt it on. Takes about 5 mins for both arms.

Appreciate it!

Molds for carbon fiber arms would cost thousands of dollars to make and the machinery to process it would cost much more.  Then , of course, there is the cost of the carbon fiber which isn't necessarily that expensive.

I used to own a recumbent bicycle and it had a (heavy) fiberglass seat shell. I made a few ultralight versions of the seat shell from carbon fiber and/or kevlar.

The first step was to make a fiberglass mold from the existing seat shell. Then I used the mold to make the new ultralight versions, which I vacuum bagged (that makes it lighter by squeezing out extra resin). It's a time consuming and fairly labor intensive process, but there's nothing particularly expensive about it---certainly nothing in the thousands of dollars range. A high quality vacuum pump costs a couple hundred dollars, but that would not even be necessary for something as small as crank arms. The amount of material (carbon fiber, epoxy resin) needed for crank arms would be trivial. The hard part would be making a mold/jig that would keep everything aligned perfectly as it cures. Time consuming and tedious? Yes. Expensive? Not really.

Now, I'm not recommending that anybody do this, since it would be more trouble than it could possibly be worth. On the other hand, carbon fiber crank arms would look totally awesome on a Hobie, especially if you molded in your own custom design...

Anyways, IMHO anything beyond solid 6061-T6 aluminum crank arms is way, way, way overkill for this application.

Molds for carbon fiber arms would cost thousands of dollars to make and the machinery to process it would cost much more.  Then , of course, there is the cost of the carbon fiber which isn't necessarily that expensive.

I used to own a recumbent bicycle and it had a (heavy) fiberglass seat shell. I made a few ultralight versions of the seat shell from carbon fiber and/or kevlar.

The first step was to make a fiberglass mold from the existing seat shell. Then I used the mold to make the new ultralight versions, which I vacuum bagged (that makes it lighter by squeezing out extra resin). It's a time consuming and fairly labor intensive process, but there's nothing particularly expensive about it---certainly nothing in the thousands of dollars range. A high quality vacuum pump costs a couple hundred dollars, but that would not even be necessary for something as small as crank arms. The amount of material (carbon fiber, epoxy resin) needed for crank arms would be trivial. The hard part would be making a mold/jig that would keep everything aligned perfectly as it cures. Time consuming and tedious? Yes. Expensive? Not really.

Now, I'm not recommending that anybody do this, since it would be more trouble than it could possibly be worth. On the other hand, carbon fiber crank arms would look totally awesome on a Hobie, especially if you molded in your own custom design...

Anyways, IMHO anything beyond solid 6061-T6 aluminum crank arms is way, way, way overkill for this application.

Not to be argumentative, but I disagree with the building of the crank arms out of carbon fiber.  I have worked in the industry for a few years.  Yes, something like a bike seat is fairly simple to hand lay up and vacuum bag cure. Because of their thickness and dimension requirements, crank arms would be a different story.  To get consistent results you would probably need to have a mold CNC'd out of aluminum and use a compression molding process or possibly use an autoclave.  The carbon fiber would need to be prepregged to get the correct fiber/resin ratio for strength.  I'm not saying it wouldn't be do-able otherwise but the results would be iffy, time consuming, and prone to failure.
I do agree that solid aluminum is the better option.

Nice going. Count me in for a set. Let me know the paypal account to route the money.
The worst is having a hobie shaft break especially on a hot bite. --Keith

Add me to the list!

Molds for carbon fiber arms would cost thousands of dollars to make and the machinery to process it would cost much more.  Then , of course, there is the cost of the carbon fiber which isn't necessarily that expensive.

I used to own a recumbent bicycle and it had a (heavy) fiberglass seat shell. I made a few ultralight versions of the seat shell from carbon fiber and/or kevlar.

The first step was to make a fiberglass mold from the existing seat shell. Then I used the mold to make the new ultralight versions, which I vacuum bagged (that makes it lighter by squeezing out extra resin). It's a time consuming and fairly labor intensive process, but there's nothing particularly expensive about it---certainly nothing in the thousands of dollars range. A high quality vacuum pump costs a couple hundred dollars, but that would not even be necessary for something as small as crank arms. The amount of material (carbon fiber, epoxy resin) needed for crank arms would be trivial. The hard part would be making a mold/jig that would keep everything aligned perfectly as it cures. Time consuming and tedious? Yes. Expensive? Not really.

Now, I'm not recommending that anybody do this, since it would be more trouble than it could possibly be worth. On the other hand, carbon fiber crank arms would look totally awesome on a Hobie, especially if you molded in your own custom design...

Anyways, IMHO anything beyond solid 6061-T6 aluminum crank arms is way, way, way overkill for this application.

Not to be argumentative, but I disagree with the building of the crank arms out of carbon fiber.  I have worked in the industry for a few years.  Yes, something like a bike seat is fairly simple to hand lay up and vacuum bag cure. Because of their thickness and dimension requirements, crank arms would be a different story.  To get consistent results you would probably need to have a mold CNC'd out of aluminum and use a compression molding process or possibly use an autoclave.  The carbon fiber would need to be prepregged to get the correct fiber/resin ratio for strength.  I'm not saying it wouldn't be do-able otherwise but the results would be iffy, time consuming, and prone to failure.
I do agree that solid aluminum is the better option.

ou aren't saying that carbon fiber crank arms in general are a bad idea, right? Just that homemade ones are?

Correct. Properly made carbon fiber crank arms would be awesome.

couldnt you just have a foam piece made, wet lay up... vacuum bag it... then once it dries have the sleeves and bushing drilled and pressed? or how about ordering a pre made square tube and make it... the same way as a alluminum solid stock. pouring expanding foam within the CF tubing it does increase rigidity doesn't it? CF is possible just more expensive and time consuming.

I am all set up with PayPal to start receiving payments for the arms. As soon as the orders some in we will get the production sent off to the shop.

Please PM me your email and how many sets you would like. You will receive an invoice from 'Seattle Innovations' for $85 for each set plus $6 for shipping.
Thanks guys, the soon we get payments to the sooner we can start fabrication.
~Bill

Did ya send out the invoices?

I am going to send them out in batches .... The first batch will go out this weekend

Count me in for a set

I looked through the entire thread for a picture of the finished product.

I looked through the entire thread for a picture of the finished product.

I don't have a finished product. When this batch goes to manufacture will be the first sets made.
Here is a picture of what the final product will look like.

Looks good. I assume the axle that fits the standard Hobie pedal is a threaded attachment rather than press ft? Same threading then also accepts standard bike pedals. Well done concept.