2017 YT Jeffsy 29
Size Tested: Large
- Drivetrain: Shimano XT
- Brakes: Shimano XT
- Fork: Rockshox Pike RCT3
- Rear Shock: Rockshox Monarch RCT3
Travel: 140 mm rear / 140 mm front
Blister’s Measured Weight: 28.7 lbs (13.01 kg) without pedals
Reviewer: 5’9”, 155 lbs.
Test Location: Moab, UT
We swung through Outerbike in Moab several weeks ago to hang out, ride some bikes, and partake in the good times that happen when bike people gather together in the desert.
If you don’t already know about Outerbike, you should; it’s a great opportunity to demo new bikes on some great trails. There are three Outerbike events throughout the year — Moab in the spring; Crested Butte in the summer; and Moab again in the fall. Each event lasts 3-4 days, and you can get more information at outerbike.com.
So we had three days to ride some of this year’s new bikes on a smattering of Moab’s best trails. And while it was a great opportunity to learn a good bit about a number of new bikes (including the one reviewed here), we only rode these bikes for a few hours each, so keep in mind that this isn’t our normal full-scale review.
YT has been making waves with their direct-to-consumer sales model and bikes that offer some pretty stellar deals. And while they started with a more downhill- and enduro-focused lineup, the addition of the Jeffsy 29 and the new (but as yet unavailable) Jeffsy 27 expands YT’s offerings into the realm of trail bikes.
I’ve spent a fair amount of time on assorted 29ers in the past few years, and I’m generally a fan of how they ride. When the geometry and suspension is dialed, they’re tough to beat when it comes to carrying speed on rough singletrack, and the better options still manage to stay reasonably maneuverable and fun.
The Jeffsy 29 certainly seemed like it checked the right geometry boxes for that perfect blend of chunder-crushing prowess that’s still fun in corners, so I was pretty excited to get one out for a spin in the Mag 7 area in Moab.
The Jeffsy 29 build options have changed a bit for the new model year (the new version is essentially a Sram X1 build), but the frame remains the same. I rode the carbon frame, which was kitted out with a Rockshox Monarch RT3 rear shock and a Pike RCT3 Fork, both set at 140 mm travel. Both of those are top of the line suspension options, so no complaints there.
Shifting and braking were handled by Shimano, with XT components except for some Raceface Turbine cranks. All of those bits have well-earned reputations for durability and performance. My only minor gripe is the big jump on the XT cassette; shifting from second gear to first gear is a big jump, is a bit clunky, and also feels unnaturally large on the trail.
DTSwiss M1900 Spline wheels are a quality performer, and have held up well every time I’ve ridden them. They’re not the stiffest wheel I’ve ever ridden, but for most people, they’re certainly stiff enough. (I do, however, dislike the terrible engagement in DT Swiss hubs, which is particularly annoying on the techy climbs of Moab.)
Fit and Geometry
The Jeffsy is fairly middle of the road among modern trail bikes in terms of sizing. YT recommends a Medium for people from 5’4” to 5’10”, and a Large for people from 5’8” to 6’2”. At 5’9”, I fall into the overlap, but I ended up on a Large.
With a reach measurement of 443 mm, the Jeffsy 29 is a pretty average Large, and at my height, the bike fell roomy but not overly stretched out. The top tube length comes in at 616 mm for the Large (again, fairly average), but the actual seat tube angle is somewhat slack. So the top tube might feel a bit longer for those with a lengthy inseam and a high seat.
The bike’s geometry can be adjusted via a flip chip at the lower shock mount, which slackens and lowers the bike. I rode the bike in the “low” mode, which yielded a 67° degree head angle, 32 mm of bottom bracket drop, and an 1178 mm wheelbase for the size Large. This puts it right in line with other bikes in this category, like the Specialized Stumpjumper 29 and the Santa Cruz Hightower.
One noteworthy aspect of the geometry that I think YT should get a lot of credit for is that the chainstays get longer on the larger sizes. Small and Medium Jeffsy’s have 435 mm stays, while Large and Extra Large Jeffsy’s have 440 mm stays. This makes a ton of sense, yet very few companies do it.
NEXT: The Ride, Bottom Line