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Shrimpalicious 2.0: Cowboys, Seafood and Lasers.

Updated: Oct 28


It all started in September 2021, on a rain drenched Squamish afternoon. Sarah Brunswick and myself were walking back to our friend Shelagh's house with an armload of takeout Sushi, and discussing what was working well on the slick, steep, rooty and rocky trails of the area. And what wasn't.


We had been there riding for a week and it had poured on us every day. Rather than retreat back to sunny dry Alberta - we stayed and stuck it out with our buddy. Our gear was perma-wet, our bikes getting thrashed by the day as grit and sand found every orifice and scratched every Kashima, but we three had each other - and our spirits were high. There was also plenty of craft beer, and a roaring fireplace to sit by each evening. Pretty decent.


As Sarah and I walked along, I recall discussing suspension behaviour with Sarah and how it applied to riding in terrain that was steep and technical. We walked past a clapped out old Ford Ranger and Sarah exclaimed, "You should build your own suspension bike Corey, and call it Shrimpalicious". We laughed. She had read the word off a decal from the back of the vehicle. Totally random. But her idea that I would build my own suspension bike stuck, and so did the name.


We didn't know what "Shrimpalicious" meant then and we still don't, but the quirky name stuck and here we are!


The collaborative creative process behind the design (aka me owing Spencer Cutten and Kurtis Peters a HUGE debt of goodwill), the aesthetics of the bike, and the subsequent execution of the first prototypes is very well laid out in a podcast called "Shut Up and Build Bikes, Episode 57". I've added a link below if you are interested in the deeper history and players involved:


https://cobraframebuilding.com/podcast/


The production version of the bike (2.0) is currently in the final design phase, and orders can be placed right now. A $500 deposit ensures you will receive your frame (or complete) in April 2023. Please visit the home page for a list of rad parts that KRUCH offers to frame customers to outfit your build. Choose your size, your frame colour - AND your anodized parts colour as well!



What is it? Besides a creepy seafood-themed mascot that is.


"The Shrimp is a simple solution to the manufacturer/brand driven complexities of modern full suspension mountain biking. It feels like a bike you have always known, with a boost of steep and chundery terrain confidence"

Chris Turner, 2022.


Shrimpalicious is a 29" wheeled single-pivot 4130 chromoly steel (American sourced 4130 steel tubing) suspension bike, with 140mm of rear travel and 160/170mm of front travel (user determined). It is purposefully designed to be long and low, with a steep seat tube angle for comfortable efficient climbing and a slack headtube angle for confident descending. It uses oversize bearings in the pivot for longevity, and allows for the use of massive dropper post sizes (180mm in the small size, 210mm in the medium, and 240mm in the large and extra large sizes). The bike has huge standover, and an expansive cockpit - designed for spirited but controlled riding. The production version uses a "flip-chip" to modify the bottom bracket height, and also allow for the bike to be run in an optional mixed wheel 27.5/29" configuration. The bike uses a 73mm wide BSA bottom bracket shell, 148mm rear axle spacing, and an overbuilt 44mm headtube. The frame is compatible with a 200mm rear rotor - or larger. ISCG tabs are available, but on request. A "plus" size rear triangle is optional and selected for during the ordering process - to run the bike in 29+ configuration when desired. The geometry chart is as below:

The bike was designed to work best in the steep loose conditions like we have here in the front ranges of the Rocky Mountains. It's definitely not for everyone, but it is definitely for people who want control on steep terrain and a bike that is very easy to tune in to that "magic carpet" plushness feel. It is also for people who want something different, where they get to choose the colour and components, and enjoy a locally made product built to last a very long time.


Features (2.0 Production version - April 2023):



The Flip Chip


Flip Chip: A "flip chip" installed in the rearward shock mount enables the rider to place the bicycle in HIGH or LOW position. It alters the bottom bracket height by ~15mm. It can be changed rapidly on the trail if necessary.


The low position sets up the bicycle as designed - the high position raises the bottom bracket for those who want more pedal clearance, and gives a slighter steeper headtube angle (To 65 degrees from the low position of 64 degrees) and slacker seat tube angle (to 77 degrees from the low position of 78 degrees). Most riders will not feel the changes this makes, and the impact on the suspension kinematics is negligible.


The "flip chip" also allows the bike to run in a "mixed wheel" configuration (aka Mullet). Placing the bike in the high position, a 27.5" wheel installed in the rear of the bicycle, approximately returns the bike to the low position.


Tube in Tube Technology (avoid this acronym)


FEA (finite element analysis) modelling of the prototype bike revealed that a huge stress concentrator exists where the shock meets the downtube, on a single pivot style suspension system. Many brands that build these style of bikes try and spread the load out with external repad (double wall using an external second layer of metal) style reinforcement. Frankly, I hate how this looks.


In the process of designing the prototype bikes, a design which utilizes an internal gusset was created. A heavier-walled piece of 4130 tubing is first laser cut into a specific webbed shape, then turned down on a lathe so it can slide inside the downtube. A series of plug welds nests the internal gusset into place, then the shock shuttle mounts transect both the internal gusset and the downtube - and are welded in - seaming together the shock mounts, the inner gusset, and the downtube.


The downtube is beyond strong. It is virtually unbreakable, but still very light - and to my eye - quite aesthetically pleasing.


In fact, every aspect of the frame has been subjected to FEA, and the various design decisions have all been driven by and supported by that modelling.



SLM Components: Additive Manufacturing.


SLM (Selective Laser Melting) components are used extensively throughout Shrimpalicious. The 316L printing process is able to create shapes which are not feasible to create via traditional methods. The following parts are created using 316L stainless steel SLM - essentially 3D printed stainless steel:

  • Proprietary KRUCH dropouts (UDH - universal derailleur hanger on drive side, Paragon brake mount compatible on brake side).

  • Main pivot assembly for both regular and plus size rear triangles.

  • Rear shock mount (with integrated flip chip).

Other KRUCH bicycles use 316L parts (Gnartail 2.0, Tauntaun), and the results have been truly striking. The ride quality has to be felt to be believed. The 316L is strong but also ductile, and lends itself nicely to enhancing the inherent ride qualities of steel.


Fun fact? By using 316L SLM parts we were able to save 2lbs! over the weight of the prototype frames - and the production versions are actually stronger than the prototype frames.



Kinematics, Geometry. The Special Speed Sauce.

The Shrimpalicious is a single pivot design, a very tried and time-tested configuration in mountain biking suspension design. However - we started there and (in our opinion) refined the design to a place where the bike is totally fit for our specific purpose.


Three graphs have been presented below, each one speaks volumes about how the Shrimpalicious suspension behaves:

  • Leverage ratio: The bike has been given a leverage ratio that is slightly regressive, and becomes even more regressive as it gets deeper into the travel. The real world translation of this characteristic is that the bike will have active suspension feel even when it is sitting deep in its travel. The bike literally will feel plusher - as it gets deeper into its travel. If the bike is set up right, it very much becomes a real "plow machine" - able to blow through rocky and rooty sections with ease while providing only a minimum of harsh feedback. By building a bike with that magical plush ride quality, the main focus of the rider becomes line choice and proper technique. The bike being steel provides a high frequency vibration dampening just by nature of it being made of steel - layering on a regressive leverage ratio makes the bike feel as if it has much more travel than it actually does.

  • Anti-squat: To combat "pedal bob", generous anti-squat has been added to the mix. However the anti-squat doesn't really start to activate until about 25% into the travel, which allows some compliance while climbing technical terrain. Combining a solid anti-squat curve with a steeper seat tube angle provides comfortable and efficient climbing characteristics - perfect for those longer epic days on the trail.

  • Anti-rise: To combat "brake jack" (where the rear end of the bike would tend to lift under braking), anti-rise is deployed. Most modern suspension bikes have this feature - and Shrimpalicious is no different. The specific curve is given below.




Plus Sized Tires. When Chubby is a Good Thing.

It is no secret that plus tires give better traction than the regular sized counterparts. Plus tires came on the mountain bike scene with a flash a few years back, but many manufacturers didn't jump on the bandwagon - however the custom bike scene embraced them and still does (to my knowledge, Shrimpalicious is unique in the ability to have 140mm of rear travel AND run a 29+ tire).


Sure, 29+ is more difficult to pedal around - in much the same way that a Fat Bike is. However, like a Fat Bike - the traction is unbelievable on descents with loose or wet conditions. It's up to you to decide which option you want - or maybe you want both?


The two rear triangle options (interchangeable):

  • Standard: Able to accept up to a 29 x 2.5" tire, and run a 32T maximum chainring.

  • Plus: Able to accept up to a 29 x 3.0" tire, and run a 30T maximum chainring.

My personal Shrimpalicious (Anna Nicole) runs the plus-sized option, as below:


Water bottle accommodation

All four sizes of Shrimpalicious allow for a water bottle to be placed inside the frame, on the top of the down tube.


This may seem like a minor detail, but in fact it is not to those this matters to. The smallest size uses a curved downtube to allow the bottle to fit in there - with no resulting effect on kinematics.


Taking Pre-orders Now

Pre-orders may now be placed for April 2023 delivery. Reach out if you have any more questions or comments for me!


KRUCH










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