Tested: Diamondback Steilacoom RCX Pro Disc ‘Cross Bike

Cross Pro Review
Meet an attractive, affordable and durable workingman’s cyclocross race bike

Why You Want

You’re looking for an attractive, affordable and durable workingman’s cyclocross race bike, want to dip your toes into the disc brake arena, and you don’t race in horribly muddy conditions on a regular basis.

Pros

After a month of riding, training and twice racing aboard Diamondback’s attractive alloy-framed Steilacoom RCX Pro Disc, the No. 1 takeaway was how absolutely bomber and stiff the oversized Easton EC90 XD carbon fork is. When combined with a 1.5” carbon steerer and a set of Avid BB7 mechanical disc brakes squeezing a 160mm front rotor, braking shudder was non existent. Gone. Kaput. Even on steep, bumpy terrain, I found myself carrying more speed for longer, confident that when the time came, I’d be able to scrub speed in a quick and controlled manner (with one exception, which I’ll explain below).

I’ve also become a believer in tubeless tires for ’cross. The Steilacoom RCX Pro Disc comes stock with Easton’s EA90-XD disc specific road tubeless wheels wrapped with Michelin Cyclocross Mud 2 700x30c tires. Normally I run tubular tires during races, so at first I was cautious, not willing to dip below 30psi for fear of burping a tire and crashing. But during two races at the U.S. cyclocross national championships in early January, I went for broke, dropping tire pressure to 26psi front and rear, which is about what I typically run with tubulars.

Easton’s EC90 XD carbon fork puts an end to front brake shudder, while the rig’s tubeless tire set-up is an affordable alternative to running tubular tires.

The change in tire pressure didn’t yield any great results (I blame that on my mother-in-laws Christmas cookies). But I never had any burping issues, while still reaping the ride smoothing, bump-absorbing benefits of running low tire pressure on a decidedly rough course. It would be interesting to see if this held true with a larger volume tire, which this frame has ample room for thanks to its generous tire clearance.

The cockpit is well appointed, with FSA K-Force carbon handlebars and stem. A WTB Silverado saddle and 27.2 FSA K-Force seatpost continue the theme of good looking, lightweight components.

Finally, props to the SRAM Force 10-speed drivetrain. It’s not fancy or super light, and it suffers from a slightly mushy feel. But during this month-long testing session, which included one race in horribly muddy conditions, shifting was consistent and reliable beginning to end.

The frame’s flattened top tube makes shouldering more comfortable; an array of FSA carbon components add stiffness.

Cons

As mentioned above, braking performance, thanks to the mechanical disc brake system, was significantly improved over the basic cantilever set-up on my personal ’cross racer, with one significant exception.

Three days before my first race at cyclocross nationals, nearly a foot of snow fell on Boulder. Come my mid-week race, with the sun shining and the wind blowing, all that white stuff was morphing into a mess of viscous brown gunk, grit, grime.

On the first two laps of what ended up being a four-lap race, I had true mechanical advantage, able to carry more speed and brake later while maintaining control headed down the course’s handful of technical downhill sections (made even worse by the mud). But by lap No. 3, with the effects of the elements taking their toll, braking power started to fade. A lap later, I basically had no brakes at all and ended up running the course’s steepest downhill section to avoid ending up on my backside.

The culprit, of course, is the nature of the mechanical disc brake systems and organic brake pads. Unlike hydraulic disc brakes, which self adjust, there is no mechanism that automatically takes up cable slack or moves the pads closer to the rotor as the brake pads wear, which can happen at an accelerated rate when conditions are harsh, as they were in Boulder.

Our first race aboard the Steilacoom RCX Pro Disc was an exceptionally muddy affair.

Additionally, organic brake pads, such as those stocked on the Steilacoom RCX Pro Disc, tend to wear out quicker than their sintered counterparts. (The upside is that organic pads tend to make less noise and have a shorter break-in period.)

On the BB7 system, gradual pad wear isn’t such a big deal when you’re cruising around for fun. As soon as you notice a little brake fade, simply stop, turn the red adjustment knobs on each side of the caliper, which moves the pads closer to the rotor. When this is no longer effective, replace the pads.

But none of that can be done on the fly on this bike, making it hard to execute in the middle of a race, unless you can switch bikes in the pits and have a supporter make the adjustment for you. It’s also worth noting that three days later, with pads adjusted (but not replaced) I raced the Steilacoom RCX Pro Disc again in dryer conditions and had no problems whatsoever.

Left: Red adjustment knobs on the calipers allow pads to be taken in. Right: The frame has ample tire clearance, which is great for muddy conditions.

When I explained this situation to the folks at Diamondback, they acknowledged that brake fade is something that can occasionally happen in exceptionally harsh conditions, but said that this was the first time they’d heard of it happening on this bike. I’ll attribute that to the truly nasty race day conditions in Boulder.

My only other real beef with this bike is the weight and somewhat harsher ride of the frame when compared to the carbon fiber steed I normally race aboard. As built, the Diamondback Steilacoom RCX Pro Disc registered 19.7 pounds without pedals, which is 2.5 pounds heavier than my three-year-old Ridley X-Fire spec’d with SRAM Force, alloy wheels, and tubular tires. And yes, that extra heft was noticeable, especially when it came time to pick the bike up and run up the national course’s two sets of daunting stairs. On the upside, the frame’s flattened top tube made shouldering more comfortable once you got the bike off the ground and situated.

As for ride quality, aluminum has never been known for its pillow-like character, and that certainly didn’t change here. Despite the frame’s flattened seat stays, which are intended to smooth the ride on rough courses, it was bumpy going at times, even with lowered tire pressure. The flip side is that this frame is incredibly stiff, meaning no wasted energy, especially during hard, out-of-the-saddle efforts. So yes, it’s a trade-off.

RoadBikeReview Final Take

Having raced ’cross aboard a carbon fiber bike for the last three years, it would be hard to go back to an aluminum frame because of the weight penalty and somewhat harsher ride. But I love the looks of this bike and it’s hard to argue with the $3,400 price tag, which is thousands cheaper than comparatively spec’d composite bikes.

For me then, the Steilacoom RCX Pro Disc (which is named after a small town on the Puget Sound), is a solid entrée into the world of competitive cyclocross racing. It performs well enough to be at home in any cat. 4 or 5 showdown, and if you start climbing the ranks and want to upgrade to a carbon fiber bike, the Steilacoom RCX Pro Disc would make a great pit bike that could serve as a capable commuter during the week.

Rating: 3 out of 5

The Diamondback Steilacoom RCX Pro Disc: a capable entry-level racer with solid looks.

Full Spec Details
  • Weight: 19.7 pounds (size 59cm frame without pedals)
  • MSRP: $3,500
  • Frame: DBR CX PRO Spec. Fully Butted 6061-T6 Alloy Competition Cyclocross Geometry, Formed Top tube w/integrated Tapered Headtube, lightweight formed Down tube, with Formed and butted seat tube with braze-on FD hanger, Disc Specific Drop out
  • Fork: Easton EC-90XD Carbon w/Tapered 1.5 Carbon Steerer for Disc Brake
  • Wheels: Easton EA90-XD DISC Specific, Road tubeless, w/o braking surface
  • Hubs: (F) Easton EA90-XD, 20h, 9mmx100mm QR w/6-bolt CNC machined rotor mount, sealed cartridge bearing (R) Easton EA90-XD 24H, 10mmx135mm QR w/6 bolt CNC machined rotor mount, sealed cartridge bearing
  • Tires: Michelin Cyclocross Mud 2 700x30c
  • Shifters: SRAM FORCE double tap 10 speed
  • Front derailleur: SRAM FORCE FD Braze-on
  • Rear derailleur: SRAM FORCE 10-speed, replaceable rear derailleur hanger
  • Crank: SRAM S950 10spd Carbon Monocoque Arm, Cross Crankset BB-30 46,36t
  • Cassette: SRAM 1070 10spd (12-26t)
  • Saddle: WTB Silverado Team Black, Nicro tubular rails
  • Seatpost: FSA SLK, 27.2 Carbon
  • Handlebar: FSA SLK COMPACT, UD Carbon, 125MM Drop, 31.8
  • Stem: FSA SLK Carbon, 31.8
  • Headset: Cane FSA NO.42 Sealed Angular Contact Bearings, for 1.5 Taper
  • Brakes: AVID Mech. BB7 Cross Brakes w/160mm front, 140mm rear rotors
  • Brake Levers: SRAM FORCE double tap
  • Sizes: 50cm/SM, 53cm/MD, 56cm/LRG, 59cm/XL

More Info at www.diamondback.com.

Tested: Diamondback Steilacoom RCX Pro Disc ‘Cross Bike Gallery
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

We ran Easton's EA90-XD DISC specific, road tubeless wheels at low pressure without an issues.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

SRAM's 10-speed Force drivetrain was a solid performer.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

External cable routing makes the bike easier to work on.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

This decorative plate on the top tube helps protect it from cable rub.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

A carbon FSA 27.2 seat post takes some of the sting out of rough courses.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

A BB30 bottom bracket ensures maximum power transfer.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

Avid's BB7 disc brakes provided confident and modulated braking as long as the pads were adjusted.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

Ample tire clearance.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

Tapered headtube maintains stiffness through the bike's front end.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

The bike is spec'd with a full compliment of FSA carbon cockpit components.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

Michelin's Cyclocross Mud 2 700x30c performed admirably in exceptionally trying conditions.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

FSA components accentuate the bike's good looks.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

During this month-long testing session, shifting was consistent and reliable.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

The flattened top tube makes for more comfortable carrying.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

Red adjustment knobs on the calipers allow pads to be taken in when they wear.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

Easton’s EC90 XD carbon fork puts an end to front brake shudder.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

When put to the test in extremely muddy conditions, the bike's brakes came up short.
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

Weight (size 59cm): 19.7 pounds. MSRP: $3,400
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Diamondback Steilacoom RCX Pro Disc 'Cross Bike

A race ready rig that can double as a capable commuter.
About the author: Jason Sumner

An avid cyclist, Jason Sumner has been writing about two-wheeled pursuits of all kinds since 1999. He’s covered the Tour de France, the Olympic Games, and dozens of other international cycling events. He also likes to throw himself into the fray, penning first-person accounts of cycling adventures in British Columbia, Belgium, Brazil, Costa Rica, France, and Peru among many others. Sumner, who joined the RoadBikeReview.com / Mtbr.com staff in January, 2013, has also done extensive gear testing and edited a book on cycling tips. When not writing or riding, the native Coloradoan can be found enjoying the great outdoors with his wife Lisa.


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  • Todd says:

    Thanks for the write up Jason. I’m curious…. I see you tested the 59cm. May I ask how tall you are and whether you felt cramped or not. I’m afraid the ETT maybe be a tad short or would a stem swap help.
    Thanks, Todd

    • Jason Sumner says:

      Todd — I’m a shade under 6-4 and felt like the fit was spot on, not cramped at all. Of course fit is a highly individual thing, so always best to try before you buy. Thanks for reading. — Jason

  • Todd says:

    Thanks Jason. I realize internet fit is a bad idea, I was looking for generalizations.
    Just noticed that it comes stock with a 110 stem so a bump to 120 would more than likely do the job.
    Thanks again!
    Todd

  • Poor says:

    Wow, I was exited to read this article as I’m looking for a budget CX bike, however budget is relative I guess, because 3.5K is way too much $$ for me.

  • Willis says:

    As I started scrolling and seeing Easton logo’s, I knew the affordable was your definition and not mine. A working man’s cross bike should be around a grand! ;-)

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