# Thread: altitude 650b............

1. ## altitude 650b............

Does anyone know the actual bottom bracket height of the new Altitude 650b bikes? the website only says that it's +/- 10mm but doesn't say what the neutral bb height is................ anybody?

2. You can view all the permutations here: Ride 9 || Rocky Mountain Bicycles

3. And it depends on the tire size too. The neutral BB height is the radius of the wheel/tire when there is 0mm of BB drop. The actual rolling diameter of most 27.5" wheels with tires is actually very close to 27" diameter so the neutral BB height on the Altitude should be 13.5" (give or take - before sag)

4. The Altitudes come with Nobby Nic 2.35" tires which may be about the tallest 650B tires at 27.75" tall. That would give a BB range with the Ride 9 of 13.47"-14.2" with a median (0 BB setting) of 13.875".....if my math is correct. When I was considering the Altitude I went through this whole thing and loving the fact I could get a nice high BB setting (I live in rocks).

5. I heard OD of hans dampf was a little over 700mm. This table must be measuring at 25 psi with bike weighted?
My numbers for bb height without sag were almost identical to skidad - 13.4" to 14.1"

6. They were deriving the diameter from the rolling circumference of an unloaded wheel/tire, so they were dividing one rolled circumference by 3.1459 to get a rolling diameter.

7. Anyone have a recommended air chart for the rear shock?

8. Body weight is always a good place to start for the rear shock and then adjust up or down by 10psi at a time until you get the sag dialed to 25-30%

9. That would be SOP...BUT those high bastards up on the shore, n' all....;-)

10. But it would would have been designed while they were still in Delta.

11. 12.75 inches from the floor to the bottom of the BB shell with the shock cam set in position 8.

12. Measure to the effective center of the BB spindle, not the bottom of the shell.

13. Originally Posted by rockyuphill
3.1459 .
????
did MBA use some anti-metric conversion?
rather than 3.14159

14. Accounting for inflation - economic rather than atmospheric.

15. Demo'd this bike this morning, I'm sold. For me this rides much better than the Bronson I demo'd the other week. Just would love one more ride on my more 'local' trails to get a better feel for it but the bike climbs excellent despite the lack of rear lockout and I actually set some PRs on a couple descents that I only sort of knew on a brand new wheel size. Was very happy!

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