I was looking at the geometry of the Pace rc127+, which has a really high stack – 625 for the small and 642 for the medium, 140mm fork unsagged
I was comparing it to other 27.5+/29 bikes and none even come close in stack
The head tube length of the Pace is short, it has slightly more bottom bracket drop
Outside fork A-C, head tube and BB drop, what can affect stack height?
I couldn’t figure out how pace got the stack so high compared to other bikes.

Fork length + head tube length + BB drop.

Here’s the geometry chart for a Kona hardtail with 100 mm forks. The 17″ frame has a stack of 601 mm. If you add 40 mm to that for the longer fork on the Pace, you get 641 mm, which is pretty much the same.

http://2015.konaworld.com/kula.cfm

Don’t forget that the stack height on hardtails always reads higher than it is once you’re on the bike – as the fork sags the bars drop much more than the BB does.

The head angle makes a marginal difference. And an external lower cup on the headtube will add a little more stack height too.

Zero 29 stack for ML is 661mm. And its a riot to ride.

Fork length + head tube length + BB drop.

I thought so but I began to doubt myself when I couldn’t get it to add up

Although head tube angle will change the rate of stack height change to fork length change but the difference for different angles is minimal

I used the slackline originally because I ahve both sagged and unsagged figures but gave up because I don’t know the difference. In fork A-C. Then the Sherpa and Solarismax b/c they are 27.5+/29 but quoted with 120mm and even accounting for diff. in BB and fork couldn’t get within 20mm. That Kona is an good comparison, cheers.