I am curious. I see lots of people using straight wire, spring steel etc to run the linkage between the servo and the retract. Is it possible to use a flexible cable instead? Or do you need the rigid quality of a solid wire? I am getting set to build a king kobra and I am going to use mechanical retracts but there is not enough room to put a retract servo in with a direct line of sight to the nose gear...

with a cable I do not think you will get the gear to lock in the push position.I could be wrong but you would have to limit the slop.I don't see a problem locking when the cable is pulled by the servo

Could you use flexible cables in pairs (each cable pulling the gear in a different direction), acting as a pull-pull system?

Just an idea, if there is no room for direct linkage.

I have used regular red Sullivan Gold-N-Rods with no problem. Just make sure the red sleeve is well anchored

You could do a pull/pull system to a bellcrank with a short rod connecting to it. Simple and very effictive. My only concern for the sullivan rods is the outter sleeve needs to be sanded very coarse and epoxied in very well. But it should work as well.

It may be worth noting that you don't NEED a straight lin to the retract. It's very common to have a bend in the pushrod

...wups..

Thanks for all of the great input. Gives me some ideas to play with!

Minnflyer, what size of push rod do you normally use with 40-60 size mechanicals, 2-56 or 4-40? Spring steel or standard?

2-56

I am building a Tiger 60 (Deluxe).  The Deluxe kit is not made anymore but Goldberg will still send the plans and die cut wood necessary to complete the mod for a small price.  I have looked at many retract gear trying to decide which will be the most reliable and also not too expensive.  Mechanical are the cheapest, but I decided to go with air up/ spring down.  Or is it spring up/air down.  Either way, they are made by Robart and you can get them from Tower for about 120 bucks for 2 mains.  Only 1 servo required and you can mount it in the fuselage.  The gear is activated by an air valve which is activated by the servo. 
<font color="#00265e">http://robart.com/retracts/6-12lb510.aspx</font>
That is the link to Tower.  Check it out.  Just another option to look at if you havent allready picked up your gear.