How can I recover bitcoins sent to derived addresses in Electrum?
Electrum and Mycelium Gear both use BIP32 for address derivation from a master seed, but Electrum is not BIP39 compatible. Thus you need to take the master seed (BIP32 Extended Key, iirc) and restore it in a new Electrum wallet, and that should work.

Alternatively, if you want to get individual address private keys you can use http://bip32.org - my suggestion is to use the "Download ZIP" function at the bottom right of the page, and work with the keys offline, otherwise there is a chance that compromised code could expose your private keys.