Over the weekend I got out on the RCX a couple times in varying conditions.
It started as a test ride down to the train station, and with the relatively mild temperature I decided to suit up and get out for some mileage. I didn’t even bother to pump up the tires- I just gave them a quick squeeze to make sure they had some pressure then hopped on and went.
My weird spec was just about perfect and the knobby tires allowed me to ride down the driveway and zip right down our slippery, slushy road without incident.
On dry pavement the ‘cross tires (over 400 grams and 36c wide on my Crest 29er rims) rolled fairly smoothly for their girth and have been holding air (tubeless) remarkably well after I added enough sealant. The road was mostly clear, but motorists were not looking for me and it was good to have the confidence to be able to ride onto the unplowed shoulder if necessary. If I were heading out with a group of riders on dedicated road bikes I’d probably switch to true road tires and tubes, but for my purposes this is fine for now. It started to snow pretty heavily on the way back so I was glad to have the additional traction to stay to the right of the white line with confidence.
Fortunately the RCX doesn’t ride like an almost 20 lb bike and snaps right up to speed. I could imagine with lighter wheels and proper ‘cross setup it would be an absolute rocket on a cross course. The wheels- Chris King hubs, DT Competition spokes, alloy nipples & Stan’s Crest 29er rims- are about 1700 grams, and that’s just about a full pound heavier than the Fulcrum Racing Zeros on the road bike. The fit was awesome- identical to my road bike, and the handling felt very familiar and balanced.
The brakes were a letdown- strong at first and predictable at low speed but quickly over matched above 20 mph. That could be better with the TRP double piston brakes, and I’m likely to try those for true cross racing, but they’re too pricey to subject them to the salt.
While researching gravel bike setups I found some interesting things on Tyler Wren’s blog (both pictures jacked from tylerwren.com). Jamis, his sponsor, has provided him with prototype bikes the last two years for the Crusher in the Tushar. Tyler’s won the race twice so he knows what he’s doing.
In 2012 he was on the Supernova, their disc cross frameset with Di2 and mountain bike wheels.
In 2013 he was on their Endura, their distance road bike with Vittoria cross tires, the same drivetrain but Dura Ace C20 wheels and road caliper brakes. It’s easy to sound like a conspiracy theorist, but what I read from this is that even though he’s got a proven gravel racing track record Tyler is not a disc convert. Of course it’s easy to speculate and races like this are a great testing ground for new products, but I would say the biggest reason for switching back to standard road wheels and calipers is that they’re not only lighter but they are better at slowing you down from high speed.
There aren’t any specs offered about the weight of either bike, but in ‘cross it’s widely accepted that even the lightest disc brakes add a pound to the bike so I would assume that was one of the major drivers to switch back. Within pure cross racing weight is less of a factor, and if you are a European superstar your bike is so light anyway that it’s less of an issue. A privateer on mid-level components is looking at spending well over $4,000 to get a disc equipped bike with mediocre wheels that weighs less than 20 pounds complete. For all of the weirdness my RCX’s build it’s still in-line with bikes costing at least that much and although it’s a size bigger it’s the same weight as Carrie’s mid-level aluminum Raleigh RX 1.0 and my old steel Swiss Cross. If you’re running disc it’s hard to consider anything other than ti or carbon based on weight alone.
I’m not entirely anti-disc, and I think they work great for true cross racing. With some tweaks to the build- primarily in wheels and tires- the RCX is going to be a super capable and fast race bike. For now the RCX it’s perfect.
And if I were buying a bike for pure road use I’d definitely not get one with discs. I could still see some benefit for discs in a gravel bike, but I’m going to suspend judgment until I try a higher functioning model.