A series of poorly thought-out choices recently led me to the start line of what seems to be the least technical and most climbing-focused mountain bike race in existence. The Leadville Trail 100 might lack technical singletrack, but it is no small physical challenge, even more so when you can see the ocean from your house and plan to arrive two days before, allowing for no acclimation. I fired off a few furtive emails asking for advice and did some back of the envelope calculations myself, and it became very clear that I’d be able to put out a pitifully small number of watts on the ascent of Columbine, so I’d better opt for a lightweight bike. I could, of course, have backed off the IPAs, but what’s the point of training if you can’t crack a beer or eat a cookie afterward?
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And so, I found myself in the market for a hardtail cross-country bike, a bike that is meant for racing. Luckily, thanks to the growth of the NICA scene, the race hardtail remains alive and well. The bike that immediately came to mind, and one I have been itching to get some time on for months now, was Cannondale’s impeccably well-designed F-Si Throwback frame. Head-turning aesthetics and nostalgia-evoking graphics aside, the bike exudes the kind of razor-sharp focus on a singular goal that I don’t see much in bikes these days, it’s a very fast, very light cross-country bike and it makes no apologies for it. If this bike was a dog, it would be a whippet, the sort of dog that needs a coat when it’s cold, and has legs that look impossibly skinny, and doesn’t make sense at all until you see it in motion, when everything comes together in a blur of blinding speed that it’s hard not to respect.
The first thing you’ll notice about the F-Si is the Lefty Ocho fork, or perhaps “tine” is more appropriate because it looks nothing like the thing you use to eat your dinner. Before I’d even ridden the fork, I liked it more than previous Lefty models. It uses a standard steerer tube, and installing the quick-release caliper and wheel takes seconds and a 5mm Allen key. There’s a cable-actuated lockout now, as opposed to the finicky hydraulic lockout on the previous model. The Ocho is also 250g lighter than previous models thanks to the removal of the double crown. And yes, that means it looks like half of an RS-1. With 100mm of travel, an easily accessible valve to dial in pressure (which takes a bit of tinkering thanks to the higher pressures in this single-leg design), and adjustable rebound and compression, the fork isn’t that hard to dial in.
The Ocho was super active, more so than other cross-country forks I’ve spent time on. The fork’s excellent small-bump sensitivity is largely thanks to the roller bearings that have always made Leftys some of the most active XC forks on the market, and plenty stiff enough. No, it isn’t a RockShox Pike or a Fox 36, but it isn’t supposed to be. It’s a damn light, damn smooth, and damn good-looking fork.
The frame itself also updates a classic design. It might look like a ’90s hardtail, and I might have broken some poor guy’s heart at Leadville when I passed him on what he pronounced to be “A bike that looks older than you are!” (I’m 32; I just look younger when I’m smiling from ear to ear because I don’t have to climb up any more 12,500-foot mountains.) Beneath the Clinton-era paint scheme, there’s a hardtail with progressive geometry. A 69-degree head angle, combined with a 55mm of fork offset makes the bike feel much less nervous than the steep hardtails many of us grew up riding. I went back and forth between the F-Si and a more old-school geometry Viathon hardtail before writing this. Each time I hopped on the Viathon, I was struck by just how much more I felt like I was about to brake with my face when tackling steep terrain. Cannondale has always been a master of geometry, which is why we forgive the odd proprietary parts and annoyingly idiosyncratic wheel standards. The F-Si is a continuation of this trend. I didn’t want to like a bike that requires a unique wheelset and doesn’t permit you to use most cranks, but it’s just so much fun to ride.
The F-Si’s thin carbon stays and 27.2mm seatpost give a bit of rear-end compliance, enough to save my back even after 100 miles of Colorado washboard. You could fit a dropper if you want, but the spot-on angles and the unapologetically racy build make it seem like sacrilege. With the bar-mounted fork lockout, you’d have to get creative with a lockout lever anyway.
Of course, there are the usual Cannondale quirks, you more or less have to use A SRAM Eagle or Cannondale crank, but the SRAM crank yields a Q-factor that’s too wide for my liking. Cannondale’s cranks are great, but if you want that full groupset look, you might have to look elsewhere.
I built the F-Si with Shimano’s 12 speed XTR, yielding the most proprietary wheelset in existence thanks to Shimano’s Microspline freehub standard, and the Cannondale’s lefty-specific front hub and offset AI rear. I had Ride Fast build up an incredibly light set of hoops, which have stood up to everything I have ridden them into. Consider that I have plenty of road wheels that weigh more, and feel flexier, and I can’t find much negative to say about this build. My tire choice, a Maxxis Rekon/Ikon combo, was much less lightweight and roadie, but given the fact that whole bike weighed in at 20lbs with sealant, I felt like I had enough wiggle-room to ride something that A) wouldn’t puncture and B) would let me really get the most out of the F-Si’s surprising capability on challenging trails.
A cross-country bike has always felt like a bit of an indulgence to me. I know they feel great climbing, and the F-Si feels akin to a road bike on smoother climbs, but I didn’t want another bike in my shed that I really wouldn’t ride very much unless I had a number on. But the F-Si isn’t that bike, it’s capable enough to be fun as well as light enough to be fast.
So who is this bike for? Retro grouches? Not really, it’s an entirely modern mountain bike. Racers? Certainly, at 19lbs for an XL build with a supple and active 100mm of travel, the F-Si almost makes me want to ease off the burritos and re-up my ridiculously expensive USAC license. Roadies who want to try MTB? I mean, sure, but isn’t that what gravel bikes are? But the F-Si need not be limited to racers. If where you ride isn’t that rocky, if your rides are as much about logging big miles as hitting big jumps, or if you just appreciate the simplicity and precision that go into designing a hardtail that inspires the confidence of a modern bike without the maintenance, this is the bike for you.
If you love riding bikes, and riding bikes reminds you what it feels like to be 12 years old, and this was the bike you had thumb-tacked on your bedroom wall, then maybe this is the bike for you even if you had your eye on something else. Sometimes the best bike is the bike that you look down at and smile, or that makes you feel like the rider you have always wanted to be. Just do yourself a favor and don’t take it out of the box two days before Leadville, because that will remind you that you are no longer 12 years old.