Building bikes is about the journey, not the destination, right? I appreciate beautiful builds with a clear end-goal in mind, but there’s no final state to any bike I build because the evolution is the point. Particularly with mountain bikes, the frame is just a starting place. You can make the same bike feel radically different by changing the parts hanging off it.
Last summer, as my beloved Specialized Epic EVO was feeling a bit stale, I started looking around for a replacement. The option in this XC-but-capable space — perfectly coined Downcountry by our old friends at Pinkbike — are plentiful. Almost every mountain bike brand has something in the 115-130mm travel range that would be roughly suitable for my local riding. It’s also the range I think 90% of people with big trail bikes should be shopping in these days.
What is my local riding? It’s southwest Colorado. It’s dry and rocky at lower elevations and less dry but still rocky up high. The trails alternate between smooth, packed dirt, marbles, dust, baby heads, and big ol’ rocks. It’s technical but in a high-speed sort of way, not the pick-your-way-through-a-boulder-field kind of technical you might find on the East coast of the US, for example.
The Epic was the perfect bike for these trails. The new one probably is, too. You want roughly 120mm of front and rear travel. Maybe up to 130 mm in the front if you’re not racing (I do race sometimes). A head tube angle between 65.5 and 67 degrees. Suspension and brakes that can handle high-speed chunk. Tires that roll fast but don’t get sliced open too easily.
I sit on the XC end of the downcountry spectrum. I like to descend, and do so quickly (most of my meager haul of KOMs in this Olympian-riddled town are going downhill). But I need to keep up with the younguns everywhere else. I want a solid pedalling platform — this is the one place I sometimes felt the Epic could be better — combined with flickable, confident descending.
I ended up with… a Cervelo?
Weird, I know. It’s a road brand. But it’s owned by PON and the ZFS-5 borrows heavily from the Santa Cruz Blur, with a few nice tweaks. The geometry is about right, with a 66.6 head tube angle and medium (not particularly progressive) reach figures. It has a threaded BB. James Huang reviewed a 100mm version (which is just a change in fork and rear shock) and liked it. And when I was looking, it was on a good sale: Complete bike with a GX build for $3400.
A road brand that made an XC bike that I wanted to turn into a downcountry race slayer? Ok yeah, let’s do it.
Build Phase 1: Bars, tires, wheels, saddle
The decision to start with a stock build, rather than build from the frame up, has distinct benefits and one big drawback. The most significant is that I can swap out individual bits, ride it, get a feel for the change, and decide what comes next. It does tend to end up more expensive, as selling a used GX rear derailleur is not a great money-making venture. Still, it got me rolling on a bike, and changes could happen as budget allows.
The stock build was pretty decent. Totally serviceable, in a downcountry/XC sort of context. Here’s what it looked like:
Frame: Cervelo ZFS-5 120
Fork: Rockshox SID Select+
Rear shock: Rockshox SIDLuxe Select+
Wheels: RaceFace ARC
Tires: Maxxis Rekon
Brakes: SRAM Level Bronze Stealth 4-piston
Cranks: SRAM GX
Shifting: SRAM GX
Handlebar: RaceFace Turbine Aluminum
Stem: RaceFace Aeffect Alloy
Seatpost: RaceFace Ride XC Alloy (not pictured)
Pedals (not stock): Shimano XT
Weight: 27.2 lbs (12.33 kg)
Not bad, right? Given the high-end frame, it was a lot of bike for the on-sale price of $3400 USD. Good bones, as they say. Some of the stuff was heavy (aluminum bars and such) but performance-wise, no real drawbacks. The only exception was the seatpost. The lack of a dropper on a 120 mm bike was madness and an obvious attempt to hit some price point while keeping it under 28 lbs. I think they’ve since rectified this with the 2025 stock build.
So I started by adding a dropper. I only rode the stock seatpost one time and it was enough to remind me why droppers are great. I grabbed a OneUp on the recommendation of Joe at Durango Cyclery (an EC member!), who said he doesn’t see many come in broken. That’s my primary desire from a dropper. Price was reasonable, about $130 USD.
Next up, we needed to shed some weight. I didn’t want to mess with the drivetrain or wheels yet so that pointed me toward bars and tires, both of which needed to be swapped for other reasons anyway.
Tires first. Replaced the Rekons with Maxxis’ Rekon Race 2.4 model. I like these for our trails, which are dry and rocky. The smooth bits get dusty. Not a lot of roots. Lots of kitty litter in the summer. I got the 60tpi tanwall version because they look great and I’ve found they slice a bit less than the 120tpi.
Bars also had to go. I had some nearly identical RaceFace Next Carbon bars laying around. They went on, dropping a bit of weight.
I swapped the stock Cervelo saddle for a Specialized Power Mirror with the fancy 3D printed stuff. It is a cloud for your butt. Best $400 you’ll ever spend.
With the dropper added, the other weight saving measures were largely cancelled out. Total weight dropped to just below 27 lbs.
I rode the bike in this configuration for about a month. It was, as expected, quite good. Solid, predictable geometry, great pedalling platform, light enough.
The hours spent riding this roughly stock build allowed me to develop opinions about the rest of the components, and then start to prioritize what would be changed next. This is the benefit of upgrading a complete bike versus building from the frame up. And boy, did I form some opinions.
Build Phase 1.5: Wheels
The next swap was wheels. The stock RaceFace aluminum wheels were fine. But I wanted to drop some weight and FSA sent some of their new carbon hoops (the KFX i28 XC). This dropped about 400 grams and the bike certainly felt more sprightly. Interestingly, none of my times on the various local laps changed much at all. Not exactly scientific, but the idea that lighter wheels are some sort of panacea is off base, I have long believed. Faster tires make a much bigger difference.
So the build now looked like:
Frame: Cervelo ZFS-5 120
Fork: Rockshox SID Select+
Rear shock: Rockshox SIDLuxe Select+
Wheels: RaceFace ARC - > FSA KFX i28 XC
Tires: Maxxis Rekon MaxxTerra - > Maxxis Rekon Race 2.4 WT
Brakes: SRAM Level Bronze Stealth 4-piston
Cranks: SRAM GX
Shifting: SRAM GX
Handlebar: RaceFace Turbine Aluminum -> RaceFace NEXT Carbon
Stem: RaceFace Aeffect Alloy
Seatpost: OneUp dropper
Pedals (not stock): Shimano XT
Weight: 27.2 lbs (12.33 kg) -> 26.0 lbs (11.79 kg)
Build Phase 2: Suspension, brakes, cranks, chainring, bars
Swapping brakes and suspension made this bike feel like an entirely different beast. So much more control, so much more stopping power, so much more traction.
With about six weeks of riding on the mostly stock build (wheels were the most expensive change, tires the most impactful), two major issues became clear.
The first was the brakes. The four-piston SRAM Levels were… how do I put this? Bad. I think that’s the word. I did not like them. They have no power. Modulation for days, though! Downside: it’s going to take you days to stop. SRAM makes some pretty good brakes (I have a set of Codes on another bike I really like, I prefer SRAM road discs over Shimano, and a friend at SRAM reliably informs me I’ll like whatever is coming next) but these Levels are not included on that list. And it seems I’m not alone given Dave Rome’s recent review of the Cannondale Scalpel with the same model of brake.
I like powerful brakes. So these had to go.
I went left field with brake choice. I’ve long loved simple Shimano 4-pistons, XT or XTR, but wanted to try something different. And I was pretty sure a SRAM drivetrain was in my future, which would feel icky with Shimano brakes (silly, I know). So I got some Hopes XCRs in, in 4-piston.
Holy cow. So good! So powerful it took me almost a week to fully get used to them, particularly coming off the Levels. The power is similar to 4-piston Shimano but the lever feel is different. The bite point is less of a point and more of a window; a good analogy might be a good suspension fork, with a progressive increase in power. The lever itself also flexes more than a Shimano lever, which took some getting used to. The levers are also longer, so I had to play with positioning on the bar to get the fit right. Overall, very pleased with the decision to go for something different but it took three or four rides to get there. Plus that machined look is sweet.
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