Following on from some other discussions where I’ve been looking at different bikes and asking for sizing feedback a few folk have come back mentioning Ape Index.

So is it a big factor in getting a bike that fits ‘right’?

I have a +1.5 Ape Index so though should be that generally I’ll need a longer reach bike with lower standover than someone with a negative index?

No, I think its effect is misunderstood. I’d say that shoulder to hip distance determines required reach whilst leg length determines required saddle height (and preferred standover).

“Ape index” appears to be arm span minus height. I have long limbs and I am relatively broad. Ape index is +3.5″. I need my saddle high because I have long legs. I prefer moderate rather than long reach because my torso isn’t that long. I like wide handlebars.

Only +1.5″…?

What are you? Some kind of particularly short-armed T-Rex?

(In other words, it sounds to me like you’re fairly normal)

For me ape index is more around handlebar width. For me the ratio of torso length to leg length is more important (and I don’t think really a measurement that’s got a name).

For example I’m 5ft11 but I have a 34.5 inside leg. Now according to the generic wiggle size guide (first link from google) the leg is longer than average for the height. So I tend to prefer slightly shorter reach bikes with a bit more stack.

e.g my HD3 (L) has a reach of 431 and a stack of 610 (ratio of 1.42).

For comparison a 19.5″ Trek Remedy has a reach of 459 and a stack 592 (ratio of 1.29). I just don’t find that fits without putting big risers on the front. I can size down but then long legs mean huge seat posts…

No.

Ignore all the number obsessives and buy a bike you enjoy riding the way you like to ride.

plus.

Ape index does not take shoulder frame or torso length into consideration.

ie. it’s a pointless formula with regards to riding bikes.

Sizing bikes on dimensions without considering your build and other factors is risky. 2 people of the same height and limb lengths can be very differently built, so the different rider c of g or simply flexibility will mean a different set up is needed to get well balanced over the bike.