Brian Curtis has been making frames for nearly 50 years and, together with Gary Woodhouse, he’s built a reputation for beautiful yet robust brazed steel bikes. The XR650’s outwardly simple yet sorted single-pivot frame combines a tautly-sprung ride feel with stunning looks.
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Curtis XR650 frame
T45 chromoly has been Brian and Gary’s tubing of choice since 1980 and, apart from a Reynolds 631 seat tube and X44 head tube, that’s what you get here.
Both the top tube and down tube are gusset-reinforced, and there’s a small brace pipe on the seat tube, below the forward-facing seat slot with built-in bolted clamp.
The main pivot runs through a wraparound saddle plate on the down tube, with big tubular terminals stiffening the connection points with the space-frame swingarm. Multiple bracing tubes add stiffness.
The big, chunky, replaceable alloy rear mech hanger arm is a micron-perfect fit. There’s room for up to 2.8in rear tyres between the stays and behind the kinked seat tube, but even with (admittedly big) 2.35in Schwalbe tyres, the Curtis already has a relatively high bottom bracket. At 3.8kg without shock, the frame is also a kilo heavier than most carbon rivals. There’s no space for a bottle either.
Instead of one of Curtis’s 14 paint finishes, an extra £150 (to cover hand-polishing time) gets the stunning clear powder-coated finish here. It’s definitely the best way to appreciate the artistry in Brian’s unique multi-layered, rippled fillet-brazing.
There are four standard sizes but all bikes are made to order, so you can customise the head tube length and angle, frame height and length, as well as choose ‘stealth’ or standard dropper routing and full outer or stop/start cable routing.
If you want a longer bike or you’re a 40ft-gap-sending savage like team rider Jim Davage, then Brian and Gary will add stiffer/stronger tubing at no extra cost.
Curtis XR650 kit
Most XR650 frames are built into full bikes by their owners but Curtis also sells the complete build tested here.
The kit mostly showcases the frame really well, with the quieter, lighter feel of the Shimano transmission (compared to SRAM) suiting the subtle spring of the steel.
I might choose more responsive wheels than the smooth and durable Hopes, though, as well as a bigger front brake rotor and wider bar.
Curtis XR650 ride impressions
The suspension action of the XR650 is fluid and there’s still enough pedal pull-back to reward power injection through the braced back end, but it doesn’t butt into blunt edges or hang up on roots and rocks.
The kinematics of the frame suit the Fox X2 shock perfectly too. On some bikes we have to spend ages tweaking the independent high- and low-speed rebound and compression settings of this damper, but I hit the sweet spot on the XR650 in just a few minutes — a testament to the massive experience of the Curtis crew, which elevates the ride of this bike.
Even Hope’s tough but sometimes unresponsive wheels can’t stop the obvious ‘warmth’ and vitality of the frame shining through, but switching to lighter carbon wheels released more of the pure steel feel, making it a joy to load up through corners or drive out the far side, with the subtle compliance of the mid-length rear end and the muscular pivot-points keeping the rear wheel connected.
But Curtis never let that flex and twang get out of hand. The front and rear ends definitely have some flow and twist between them when pushing hard but they never become disconnected. There’s no head shake or tank slap if you really slam the bike either.
Remember that all Curtis bikes are built with size/use-specific tubesets too, so deciding to go longer or slacker won’t leave you with a bike that rides like a noodle.
Curtis XR650 specifications
- Sizes (*tested): S, S/M*, M/L, L
- Weight: 15.26kg
- Frame: Custom T45 chromoly steel, 160mm / 6.3in travel
- Fork: Fox 36 Float FIT4 Factory, 170mm / 6.7in travel, 46mm offset
- Shock: Fox Float X2 Factory
- Chainset: Shimano Deore XT, 32t
- Bottom bracket: Shimano HollowTech II
- Cassette: Shimano Deore XT M8000, 11-46t
- Chain: KMC X11
- Mech: Shimano XTR M9000
- Shifters: Shimano XTR M9000 (1x11)
- Hubs: Hope Pro 4
- Axles: Boost 110x15mm front, Boost 148x12mm rear
- Rims: Hope Tech 35W
- Spokes: 32, double-butted, stainless
- Tyres: Schwalbe Magic Mary EVO ADDIX Soft 27.5x2.35in front, Schwalbe Hans Dampf EVO ADDIX Speedgrip 27.5x2.35in rear
- Wheel weight: 2.23kg (f), 2.75kg (r), inc. tyres
- Headset: Hope
- Stem: Renthal Apex, 35mm
- Bar: Renthal Fatbar Lite Carbon, 750mm
- Grips: Renthal Kevlar lock-on
- Saddle: SDG Fly Mtn
- Seatpost: Fox Transfer Factory 150mm dropper
- Brakes: Hope Tech 3 E4
Curtis XR650 geometry
- Seat angle: 73.5 degrees
- Head angle: 64.5 degrees
- Chainstay: 43.5cm / 17.13in
- Seat tube: 44cm / 17.32in
- Top tube: 60.5cm / 23.82in
- Bottom bracket height: 33.5cm / 13.19in
- Wheelbase: 1,230mm / 48.43in
- Head tube: 11cm / 4.33in
