After doombolting my own right leg off in a freak accident I got a new nice right leg in good craftmanship bionics. Do I get bonus to athletics for jumping and leaping as well as sprint or would I need 2 legs for that?

The bestest psyker in papa nurgles service.

I played a Tech Marine in Deathwatch and my understanding of that implant is that you have to have both legs to get the bonus as your normal leg cannot handle the stress that the bionic one can.

While one could argue that most people use one "dominant" leg etc, I have to agree that the bonuses really seem more plausible with two legs rather than one.

However, considering in this case a best quality leg grants no bonuses without it's partner, I would suggest perhaps considering the "+10 for a single item" bonus to contain both legs. In other words, as long as the character is willing to cut off his spare, he can obtain two as easily as he would one.

My suggestion to the GM would be what you suggest. Since you use the best leg for jumping often adding a +10 at least to athletics. To get the sprint benefit I would assume both legs should be bionic. But as you also mention, you cant really buy 1 leg, its for both so why not cut off the other one as well and get all the benefits - including +2 toughness.

Possible in-universe reasons for not wanting to cut off the second leg:

1. is horrified by the idea of replacing perfectly good flesh with technology without exceptional reason.

2. is anti-tech (probably not for this character in fairness unless they're quite mad)

3. understands that technology has faults and can fail at inopportune moments

4. doesn't want to spend even more time maintaining gear (which now includes parts of his own body)

I would rule that you get the bonuses but they are all halved since you only have one.

I think that just having one bionic leg should not be as simple as getting half the benefit, because having two balanced legs is more than the sum of it's parts.

I think I would downgrade it one step and then cut the benefits (if any) in half. This might make the replacement of your other "perfectly fine" limb more of a necessity due to the limitations of your bionics than a choice of an upgrade, since a Common-Quality bionic limb would become a half-bonus Poor-Quality limb instead, due to issues such as weight distribution, relative endurance, etc.

Decessor said:

All of these are perfectly valid reasons. I mean, c'mon. Most people wouldn't cut off a perfectly healthy leg just to replace it with a "better" upgrade, or they would already have done so with both their perfectly good legs long before whatever accident caused their predicament.