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Will Next-Gen Specialized Roubaix Feature Angled Strut For Extra Vertical Compliance?

specialized angled strut gravel bike frame added vertical flex
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Specialized’s latest published patent documents a “Bicycle Frame with Angled Strut”, wherein a completely new frame tube – an ovalized strut connecting seat & down tubes – appears designed to deliver increased vertical flex compared to a conventional bicycle frame design with a continuous seat tube. This unusual design implies impacts for frame weight, ride comfort, and tire clearance, too, possibly giving us some insights into what a next generation of Specialized’s Spring Classics road racing bike, all-road, or even gravel bike might look like…

Specialized Patent for Bicycle Frame with Angled Strut

specialized gravel bike next gen future Roubaix road bike design angled strut flex

The bicycle frame outlined in this European patent from Specialized (EP4122807A1) does away with a continuous seat tube, replacing it with a sort of floating one, if you will, suspended by a portion of ovalized frame tubing that connects it to the downtube around a third of the way up the latter’s length (58). No more traditional frame triangles in this bike… might we refer to the front polygon & rear trapezoid in the future?

The patent claims that these modifications advantageously reduce the vertical stiffness of the bicycle while substantially maintaining or reducing to a lesser extent the horizontal (e.g., lateral or torsional) stiffness of the bicycle, thereby increasing the comfort for the rider while substantially maintaining or only slightly reducing the handling of the bicycle and/or force transfer of the rider to the bicycle.

specialized angled strut gravel bike frame ovalized tubing increased vertical complicance
Cross-sectional images of the angled strut at various points along its length; the strut is thicker at the seat tube end, narrowing as it gets closer to the downtube intersection

Use of ovalized tubing such as this is nothing new, of course. Plenty of modern bikes feature flattened tube profiles throughout for engineered vertical flex. Cotic for example has been using an ovalized steel top tube on its mountain bikes and gravel bikes for years, while OneUp’s Carbon Handlebar makes use of an ovalized section between the stem clamp and bar-end regions. In both cases, despite the use of very different materials, the idea is to increase vertical compliance to better isolate the rider from the smaller lumps and bumps on the trail.

Specialized interestingly mention the potential use of steel, aluminum, OR carbon fiber for this bicycle frame. Though, judging by the seamless of curves in the drawings, this is almost definitely intended to materialize in carbon. But that likely suggests that lower-cost versions could employ similar concepts in metal construction, too.

A table within the patent document suggests the angled strut gives the bike frame 172% more deflection in the vertical plane, and 75% more deflection in the horizontal plane – compared to a conventional frame with a regular seat tube that meets the downtube at the bottom bracket. They determined those numbers with a test simulation wherein the conditions were similar to those specified for ISO 4210-6:2015-4.5, or “Fatigue test with vertical force”.

specialized angled strut frame stiffness test results versus conventional design

In the Horizontal Stiffness Test simulating ISO 4210-6:2015-4.4 or “Fatigue test with horizontal force”, the Specialized frame with the angled strut is even slightly stiffer in the horizontal plane than the conventional frame.

The patent document reads, “By increasing vertical deflection at a greater rate than the horizontal deflection, ride comfort is increased without substantially increasing the rearward saddle tilt“.

How will this fit into Specialized’s Road & Gravel Bike line-up?

specialized diverge str expert in black
The Specialized Diverge STR Gravel Bike houses a Future Shock inside the top tube

We approached Specialized for comment on this one, successfully securing the expected “No Comment” reply. Alas, we are left to hypothesize.

Let’s not forget that it was only in October of last year that Specialized released the wild-looking Diverge STR. In that design, the actual seat tube is the spring, while a Future Shock housed within the top tube damps a claimed 30mm of travel.

closeup details of specialized diverge str gravel bike with future shock suspension
You can read more about how the Future Shock works here

It’s unlikely the ‘Bicycle with Angled Strut’ described within Specialized’s latest patent document will go head-to-head against this latest Diverge STR. After all, we’re looking at smaller travel numbers of no more than 8mm here.

Specialized Roubaix carbon aero endurance comfort road race bike, photo by Etienne Schoeman
2019’s Specialized Roubaix comfort road race bike for the Spring Classics

More likely, it is a contender for an update on the Spring Classics road racing Specialized Roubaix. The cobblestone-eating Roubaix does have the official tagline “Smoother Is Faster” on Specialized’s website.

Plus, it’s been four years since we rode, covered in mud into the velodrome where Paris-Roubaix finishes on a new Roubaix. It seems about time for a new version to debut in the pro peloton. We’ll certainly be keeping our eyes open for this bike. It’ll be hard to hide such a unique frame shape, even in training.

Specialized Roubaix carbon aero endurance comfort road race bike

The comfort-oriented but still road-racing Roubaix has long been a platform for Specialized to experiment with unique vertical compliance tech – everyone remembers Zertz, right? Its latest iteration has a gen 2 Future Shock up front, and a floating/flexing aero seatpost out back. But this cropped seat tube could take comfort under your butt to a new level.

new specialized crux s-works gravel bike
The 2021 Specialized Crux cyclocross & gravel race bike

Aside from the improved comfort that may come with the increased vertical compliance, the new design could have implications for tire clearance, too. Specialized made much of their so-called ‘Clearance to Weight Ratio’ (CTR) when they released the latest Specialized Crux in 2021, claiming it was industry-leading in that regard. That evolved cyclocross & gravel frame weighs just 725g and allows for 700c x 47mm tires.

Perhaps without a seat tube to interfere above the bottom bracket, the layout could foreseeably allow for a subtle decrease in chainstay length without having a negative impact on tire clearance. And this new Bicycle Frame with Angled Strut could even end up boosting tire clearance for whatever category it ends up in – be that road, all-road, or gravel.

specialized gravel bike next gen future Roubaix road bike design angled strut flex, side profile

We shan’t hypothesize as to how exactly the angled strut frame design would impact weight. But, given that half of the seat tube is effectively missing, which previously would have directly supported the rider’s weight down to the bottom bracket – we’d presume there will need to be some additional material both to manage the flex and to physically support the rider.

If any of this unique flexing design has tickled your fancy, be sure to check out Lauf’s leaf spring rear suspension gravel bike concept for a very different solution to the same simplified vertical flex issue.

Specialized.com

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Tom
Tom
1 year ago

very curious how this will ride/pedal. Did a road ride on a MTB the other day and the tire oscillation was insufferable at high cadence with the suspension locked out. Had to put the shock in platform mode to cancel the oscillation. Likely not the same harmonic MTB tire vs Spec frame deflection, but I put it out there as something which may require damping/weight to conquer.

Dane
Dane
1 year ago

Surely we won’t see this in any UCI race. It hasn’t got triangles!

DefRyder
DefRyder
1 year ago

Interesting. I wonder how it will hold up to a heaver rider carrying gear? I’d be concerned with long term durability if I were a heavier rider with gear going over rough roads, but then again I’m no engineer or marketing specialist.

Bartek
Bartek
1 year ago

This shape doesn’t look like UCI legal so don’t expect to see it in pro peloton anytime soon.

Sevo
Sevo
1 year ago

Will be curious if they can actually patent the frame layout. Seems like plenty of ways around it though.

FrenchPress
FrenchPress
1 year ago

Bike is stuck as a 1X or has to use a Classified rear wheel. And seeing as 1X has not taken off in road and is 50/50 for gravel – big potential limiting factor.

Speshy
Speshy
1 year ago
Reply to  FrenchPress

Remember this is the same company that made a 1x specific aluminum allez for crit racing and it was dope.

Brian B
Brian B
1 year ago

So how long after the public (beta testers) get it before a recall is issued?

Roger Pedacter
Roger Pedacter
1 year ago

Clearly, Specialized’s engineers saw that Trek with the butthole in the seat cluster and said hold my beer…

Incognito
Incognito
1 year ago

This isn’t a Roubaix, it’s another more hybridy model in the Specialized line.

Dinger
Dinger
1 year ago
Reply to  Incognito

I was wondering if the Roubaix was going to have a kickstand mount as this drawing does on the NDS chain stay.

SBart
SBart
1 year ago

Rondo just presented Ruut 2.0 the other day at a closed event and it seems to be utilizing the same concept.

RelDom
RelDom
1 year ago
Reply to  SBart

And it’s already workin poece of bike. Not on the paper.

Ben Yelco
Ben Yelco
11 months ago
Reply to  RelDom

Yes, Rondo had this concept in tests, at least at the beginning of 2021. I saw it at a (closed) presentation in November 2021.

Jamie Levett
Jamie Levett
1 year ago

Still suspending the rider… When is someone going to build a minimal flex stay gravel bike with a Sid shock? With 40mm front and rear rider fatigue would be massively reduced and descending and cornering would be far faster.

Dinger
Dinger
1 year ago
Reply to  Jamie Levett

The answer is, when gravel and road riders value suspension enough to ride bikes that are 2+lbs heavier than their rigid counterparts.

Pete
Pete
1 year ago

Hello again Softride suspension….

Dockboy
Dockboy
1 year ago
Reply to  Pete

Yeah it seems like a modern cross between a Softride and a Slingshot.

Gianlucca
Gianlucca
1 year ago

This is not a Roubaix. It’s a sirrus, urban bike. Look at the hight stack. Not a road one!

Exodux
1 year ago

I’m more excited about this Specialized product since the 1981 Stumpjumper. I’d like to see where this going to go. Will it be more gravel and less road? road only? this certainly appears to be a better design than the new Diverge STR. It does appear that it would be 1x only. Maybe this will give a platform for Sram/ Campy/ Shimano to develop 1x road drivetrains or bring the Classified rear hub more mainstream.
But I’m sure that if and when this goes into production, it will be an overpriced, mass produced bike that Specialized is famous for

Yorkie
Yorkie
1 year ago

Not getting a bottle on that seattube

Adam Rice
1 year ago
Reply to  Yorkie

True. And yet they show mounting bolts. It would be easier to mount one behind.

M. Haley
M. Haley
1 year ago
Reply to  Yorkie

Nope. I think this frame might necessitate a hydration pack in warmer weather.

Max
Max
1 year ago

GT RTS – it’s already been done

Joe
Joe
1 year ago

“Plenty of modern bikes feature flattened tube profiles throughout for engineered vertical flex.”
Geek fact: the patent for a bike frame with ovalised tubes for optimised flex and stiffness goes back to 1930, by FW Evans in London.

Todd
Todd
1 year ago

Frame design provides a nice place for mud and dirt to accumulate as it’s flicked off the back tire. Having seen alternative frame designs come and go over the past 35 years of cycling, I don’t foresee this one lasting if it actually makes it to production. Regardless, kudos for trying something different.

HPC
HPC
1 year ago

It looks so similar as the 2022 reddot & IF product design winner – Geometry X

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