Originally Posted by
Redbullet
It was the cheapest reliable road bike configuration I could get years ago for trainer (around 320 EUR, heavy but still usable as replacement for road rides). Upgrading from 8 to 10 cogs was 40% of its price. Upgrading to double might set it a little more comfortable, but it does not worth the expense.
The cheapest double upgrade is to simply not use the granny.