mike kearneywrote a review of Pivot Mach 5.5 Carbon Race XT 1x Mountain Bike - 2019 on September 19, 2017
Familiarity: I've used it several times
I demo'd and rented several bikes before deciding on the Mach 5.5. Tried Pivot's Switchblade, M4, M6, 429 Trail at the demo day, and also rode a Yeti SB5C several times, as well as SC Hightower (29 and 27.5+) and the Specialized Enduro. The Mach 5.5 stood out to me as more maneuverable compared to a 29r and also more forgiving, while less wheel bounce than the 27.5+. A bit more lively and responsive than the Enduro. I also liked the M6 a lot, but the M5.5 hit a sweet spot for me, plus it seemed more modern.
The toughest time - choosing between the two great colors! Went with the Black / Blue its a great choice.
After ~150 trail miles in the Raleigh, NC area I'm very pleased with the bike and the "Race" build. Of course lighter carbon wheels would be a sweet upgrade.
I have moderate MB experience, and came off a more xc style 29r hardtail, so I'm still getting used to this bike's capabilities and learning more techniques. The M5.5 lets me be more adventurous on my lines and encourages me to do more. I certainly have much more bike than skill at this time, but it remains comfortable and super-fun on just about anything.
On the downside, shorter crank arms would probably help limit the pedal and crank hits, and the cable below the BB sits unusually far away from the frame. It looks like it could get hung up on something. I think the extra length is to accommodate rear shock travel, but I haven't confirmed it's all necessary. It would have been nice to have internal routing or more secure cable attachment in this critical area.
The bike came super well packed, but UPS still managed to damage the derailleur. CC stepped up with a quick replacement.
For sizing, I'm 5-10, 175 lb male with 32" pants inseam and longer arms. The L fits me well, but still feels quite compact. I tried the M Switchblade, and it was way too small, so be careful about Pivot's sizing guidelines.
Finally, a shout out to Gearhead Emma Giebler for all her help with getting the bike ordered!