Bike Forums - View Single Post - Looking for a titanium or steel gravel bike with a short chainstay
Old 02-02-20, 07:39 AM
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sweetspot
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Originally Posted by Lindarets View Post
@sweetspot,

Thanks for finding the Atalaya! Part of what allows the 420mm chainstay is the cast titanium BB/chainstay assembly. It's dropped on the drive side to clear the chainring and provide plenty of stiffness without resorting to a chainstay bridge. Jan-Willem (founder of Van Nichols and owner of J.Guillem) is very much coming from a road background and really spent a lot of time and effort keeping the rear end close and efficient.

As far as the press fit (BB86) bottom bracket goes, it's been a non-issue for us in the US and J.Guillem in NL. The benefit is a ~15mm wider shell, which allows for a wider/stiffer down tube and more tire:chainstay clearance as well as better-supported bearings. The tolerance and wear issues you see in some carbon frames aren't an issue- Ti stays the size it is machined to. As long as you stick to standard Shimano/SRAM/Rotor/Easton BBs and away from the oversized models designed for creaky carbon frames you'll be A-OK. We've tried some aftermarket BBs in the past and because the Ti doesn't give, the aluminum cups can be deformed enough to cause a lot of drag. T47 has some advantages for sure, but not enough at the moment to justify the added cost, weight, and parts availability challenges- and a framebuilder will have to weigh in on the impact of the larger shell on chainstay length. Shimano undermined the BB86 standard when they didn't issue frame tolerance ranges when the standard was launched- which meant that there was a lot of experimenting among manufacturers to see where the pass/fail line is. At this point we just don't see creaky BBs on JG BB86 frames- and it's rare to hear about issues with Giant, BMC, or Pivot (who all use the standard) as well. And given BB86's widespread use, you know that parts will be available long into the future.

Compliance-wise, tires and tire-pressure are by far the biggest contributor- there's an early post on the Silca blog that suggests that within a given category, the difference between stiffest and most compliant frames equates to a few psi. They have a beta pressure calculator on their website that I've found to be pretty spot-on for gravel. Seatposts can make a difference when they're engineered for compliance (Cannondale SAVE, Syntace HiFlex, Ritchey Flexlogic), but it's less noticeable on a road or gravel bike simply because there's less post exposed than on a similar mountain bike. While wheels shouldn't matter, I do think that there's something special to Spinergy's gravel wheels, for what that's worth: given the same bike/tires/pressure they ride somehow 'quieter' than similar-weight and -width wheels I've ridden. There's probably an aerodynamic downside to the larger diameter spokes, but when fitted with wide knobby tires it's probably in the noise (and they can be had with bladed spokes for a small upcharge). I've only grabbed a set off a demo bike for ~40mi and there's a hint of windup when starting from a trackstand, but I look forward to spending more time with them, especially on big days.

When building bikes for customers we have to keep those short stays in mind when it comes to SRAM AXS FD battery clearance (~38mm tire max, vs 42-43 for 1x), but aside from that they just make the bike more lively and (to me) fun. The Atalaya is a bike that a road cyclist will hop on and feel fast, both nimble in twisty singletrack and confident at speed. It's on the stiff/responsive end of the gravel spectrum no doubt, but with the right tires (up to 700x43mm or 27.5x2.1in) and pressures for your terrain is a bike that you can happily spend all day on (which, Superbowl notwithstanding) exactly what I plan on doing tomorrow. In the meantime, please feel to reach out any time!
Thank you very much! Very informative. But it got me thinking. It looks like Atalaya is the titanium bike that offers plenty of stiffness, but at the cost of compliance (you said that it is not the comfiest and I read a review stating basically the same). So you buy a titanium bike for its comfort but at the cost of stiffness and when you want the stiffness you lose comfort. So what is the point when you can get the desired stiffness from carbon and at the same time you can engineer compliance to that frame whereas titanium you can make either compliant or stiff. I am thinking about a bike like Vielo V+1 which also has a short chainstay, is plenty stiff but at the same time has nice flexing rear end and a very compliant fork.

PS thanks for bringing the Spinergy wheels into the conversation. I am certainly intrigued by them.
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