Cervelo ZFS-5 120 — SRAM XO Transmission | Bike Review

Steve rode the Cervélo ZFS-5 120 as his mountain bike all summer — SRAM XO Transmission, raced in the Minnesota XC series and ridden hard on local trails. It’s mostly stock with a few personal tweaks.

Drivetrain

The bike runs SRAM XO Transmission and Steve is digging it — with a caveat. He’d be perfectly happy on old-school mechanical; we’re a little spoiled by the bikes we have today. That said, Transmission has been solid all season.

The one drivetrain change is the chainring. With the 10–52 cassette, the stock 32T meant you only dropped into the 52 climbing cog when it was steep enough that you were barely moving anyway. Steve went to a 36T for better top-end speed while keeping plenty of climbing range — it needed a longer chain to make the swap work. He also added power by swapping in a SRAM left-side power-meter spindle: single-sided power, but it’s worked perfectly and it’s an affordable, easy upgrade if you don’t need dual-sided.

Suspension & Dropper

It’s the 120mm version — 120 up front, about 115 in the rear. The front end is capable and tracks well through rough sections. Steve has been using a ShockWiz to dial in the rear shock, which is a handy little tool for fine-tuning mixed XC/trail use.

He admits he thought the remote droppers were getting a little carried away at first, but this electronic dropper has been trouble-free for a year — none of the bleeding or burping issues some people report. If you were serious about a race where you didn’t want the dropper, you could pop in a rigid post and shed weight; he considered it but never bothered.

Setup Odds & Ends

The fork is a swap — it came off a Niner RKT, purely because the orange looked cool. The stock fork is actually a touch lighter, so this one’s just having fun with the bike. Tires are Schwalbe Racing Ray / Racing Ralph; he’d previously run tan-sidewall Vittoria Mezcals, which looked great. There are two bottle cages inside the frame.

How It Compares

Steve has spent real time on a lot of comparable bikes — Felt Edict, Trek Procaliber 9.8, Trek Supercaliber 9.8, Salsa Spearfish, Niner Air 9 RDO, a Cervélo ZHT hardtail, and a Niner RKT last year. For him the ZFS-5 climbs just as well as any of them, even the lighter Supercaliber, despite being a heavier bike. At 45, it handles anything he has any business throwing himself off — drops, jumps, rock gardens — while still being a legitimate XC race bike.

Someone at a race called it a quiver killer, and that fits. Steve also has a Niner RIP (150/140) that’s more capable and will let you get away with more mistakes, but it’s more bike than a trail like Woolly Bike Club really needs. The ZFS covers nearly everything in between without feeling like too much or too little.

The Cervélo Build Situation

Worth knowing if you’re shopping one: Cervélo launched their mountain bikes at a rough time coming out of the COVID bike boom, and the number of build variations was wild — mechanical GX, electronic GX, Transmission GX, Transmission XO, an XX SL hardtail, then Shimano builds a few months later. It was a lot to track even from the dealer side. This particular bike wasn’t a closeout, but a lot of the other builds were, and more were expected in stock in September. Pay attention to which build you’re actually looking at.