The Muur undergoes deflection and stiffness testing.

*All testing images by Microbac Laboratories

A few years now an idea was bouncing around in my head to start building custom frames locally that we could offer in addition to the all-carbon frames. I believed that there is something special about a frame that’s made exclusively for one person–there’s a certain value to uniqueness that can’t quite be captured by a mass-produced frame. Now, don’t get me wrong, mass produced frames like our Bosberg serve a purpose that few one-off frames can fulfill by offering extreme performance at a price point half that of custom. But there are a lot of people who would happily trade in raw performance for the soul and ride quality of something hand-made.

Microbac is fluent in analog dials.

Ritte, being the ever-evolving, half-shaped lump of clay that it is, had room in the lineup for a custom spin-off. But simply making steel frames, no matter how nice, just didn’t seem to be the solution: First, there are dozens of excellent traditional steel frame companies out there, and second, Ritte is first and foremost a racing company, therefore any frame we make should be competitive with anything else on the road. I loved the ride quality of a well-made steel or stainless steel frame, but I didn’t love the flexibility and weight. I’ve never liked the way ti frames ride and alloy is just kind of crap in general. But how could we make a bike with the stiffness of a Bosberg and the ride quality of a steel frame, without making it too heavy?

Force was applied to the Muur's headtube to measure deflection.

The answer was stainless steel and carbon. Builders have been combining carbon with alloy and titanium for 20 years now so there was nothing revolutionary in the idea to combine metal with carbon. But as far as I know, nobody has combined stainless steel and carbon in this way–specifically, mating carbon main tubes to an all stainless rear end. My theory was something like this: stainless steel is crisp, lively and strong, holds an epoxy bond well and doesn’t need to be painted. Carbon is stiff and helps mute vibration. Using an all stainless rear triangle focuses the springy qualities of the stainless down to the wheel, holding it to the road like a well-tuned suspension while simultaneously translating all those wonderful road sensations back to the rider. Stainless by itself can actually be a little too lively, so the carbon helps dampen the springiness and boost the rigidity at the same time. And of course, using carbon tubes and fork instead of large diameter stainless steel ones would keep the weight manageable. At least, that was the theory.

Measuring the deflection of the Bosberg front end.

So Dave, our head of production at Ritte Lab, went to work figuring out what carbon tubes could be mated to which stainless tubes and he and our builder Russ got together to determine the logistics of the build itself. As it turns out, these things are incredibly hard to build. Each lug has to be machined from larger stock to match individual Enve tubes. As a matter of fact, the only stock tubing we use on the Muur are the chain and seat stays. Every other piece has to be milled down and machined. The rear-end must be welded independently of the carbon tubes, and great care must be made not to deform any of the lugs or else the carbon won’t fit. It takes skills that few builders posses, and we’re lucky to have one of the best on our team.

The Muur's headtube gets torqued.

We had built quite a few all stainless frames, and I really loved them. But when we started test riding prototype Muur and Steeplechase carbon/stainless I was blown away by the comfort, feel and responsiveness. They were truly the best bikes I had ever ridden. Heavier than the Bosbergs and Crossbergs, but just as stiff, and with the added benefit of the enjoyable feel of an all-steel ride.

This junction looks simple, but it's insanely difficult to create.

The best test for a bike’s abilities that I have found is to take it down a descent we have here in Malibu called Tuna Canyon. It’s one-way downhill and drops close to 2000 feet, averaging over 10% with several 20% hairpins. Tuna requires breaking from 60mph to 15mph and many 180 degree turns at speed. Few riding situations can torque a frame the way G forces from this road and it’s on Tuna that the true capabilities of a bike are laid bare. Tuna also happens to be a road I’m very good at descending and had previously set a STRAVA record on my Bosberg (for what it’s worth). On my first test ride, the Muur came alive down Tuna. It made the normally intimidating road feel casual; every turn was easy, the decelerations and corners were smooth and I my tires never bounced or shuddered. Being my first time down on that bike, I decided to take it at a casual pace and not push. But when I downloaded the data back to STRAVA it showed I’d beat my previous time. I can’t imagine how fast it’ll go down there if I were to actually push it a little. The damn thing descends like Hitler to Hell.

The all-stainless on the testing fixture.

But I was in need of some qualitative data. I needed to have a justification to sell a bike that is so difficult and expensive to build. So the final step in the process was to send several frames to Microbac Laboratories in Colorado for testing. This is the same place VeloNews trusted to test bikes it has reviewed. We sent three frames to Microbac: a carbon Bosberg, an all-stainless steel and a carbon/stainless frame.

Muur Botto bracket with BB30 shell. We also use PressFit30.

This is Microbec’s description of the test: “The samples were all tested in accordance with the “Rinard Deflection Test.” The frames were mounted rigidly through the bottom bracket to a steel table. To measure stiffness at the front of the frame, a static load of 21.55 kg was applied to a steel rod secured through the headtube at a distance of 23 cm from the bottom of the headtube. Deflection was measured vertically at the point of loading. To measure stiffness at the rear of the frame, a solid steel bar was mounted between the dropouts in place of a rear axle. A static load of 21.55 kg was applied to the upper dropout, in plane with the steel bar. Deflection was measured vertically at the point of loading.”

These are the results:

Bosberg:

Front deflection: 10.033mm Front stiffness: .1

Rear deflection: 5.105mm Rear stiffness: .196

Stainless:

Front deflection: 11.76mm Front stiffness: .085

Rear deflection: 7.772mm Rear stiffness: .129

Carbon/Stainless:

Front deflection: 8.306mm Front stiffness: .12

Rear deflection: 5.436mm Rear stiffness: .184

The Bosberg on the testing fixture.

The results confirmed what we expected. Not only was the carbon/stainless frame stiff, it was just about equal in stiffness to the Bosberg, which is already one of the stiffest frames on the market. We were also interested to see how much the carbon tubing helped the overall rigidity of the all-stainless frame. Basically, what this all means is there is a reason to build the carbon/stainless other than the fact that it’s unique and looks cool. You can build up a Muur to 15 or 16 pounds, stomp on the pedals like a crit bike, and cruise the countryside like it’s your trusty steel steed. There is nothing else like it and I hope someday you get a chance to ride one.

The Muur.

Don’t forget to party,

Lanolin

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