Bike Check: UC Berkeley Students’ Handmade Carbon Mountain Bike

Jan 19, 2024
by Jacob Pashman  

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BIKE CHECK
UC Berkeley Students'
Handmade Carbon Mountain Bike


The Bike Builders of Berkeley was started in 2021 by Ziven Posner and Jacob Pashman, and is a student engineering organization dedicated to designing, fabricating, and testing bike frames. Today, the club has over 30 student members and has built four bikes in the span of two years. Completed in May 2023, the CC-1 is the club’s first carbon fiber full-suspension mountain bike.

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Pictured Co-Founder Ziven Posner and MTB Principle Engineer Blaze Harris

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The bike features a 404.6mm reach, 579mm stack, 1154.8mm wheelbase, 66˚ head tube angle, and a 73.9˚ seat tube angle. Sporting 120mm of travel front and 140mm out back atop 29” wheels driven by Sram’s GX AXS 1x12 groupset, the bike fits squarely into the trail category. The suspension layout is single pivot due to its manufacturing simplicity and predictable ride quality. The linear suspension design means a constant leverage ratio, with 100% anti-squat and anti-rise at sag, ensuring minimal bobbing while pedaling and predictable behavior while braking.
CC-1 Details
• Frame: Custom composite frame and steel rear triangle
• Shock: Fox Float DPS 140 mm
• Fork: Rockshox Recon RL 120mm
• Wheels: 29" FSA Gradient
• Drivetrain: Sram AXS GX 1x12
• Brakes: Sram G2 RSC
• Cockpit: FSA KFX SIC Integrated Handlebars and Stem
• More Info: bikebuilders.berkeley.edu



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Leverage Ratio, Anti-squat, and Anti-rise values and graphs

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Cross section of the linkage design, including hand turned aluminum bearing cups and spacers
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The team also built a custom steel gravel bike in tandem with the development of the CC-1.

Following the build's completion, CC-1 was displayed at UC Berkeley’s prospective student day, Cal Day. Immediately following, it was taken to Sea Otter, where the team was able to show it off to the world. The team was thrilled to see their creation come to life, and stoke was high at Sea Otter. The club is now looking forward to future projects, building on the lessons learned. This year, they are developing two new bikes: a steel enduro race bike and an aero carbon road bike. The team promises to return to Sea Otter 2024 with the two new bikes, and hopes to see you there. To keep up with the club’s progress, you can follow along on their Instragram and website.

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Pictured: Co-Founder Jacob Pashman riding the bike down the steps of the UC Berkeley's Engineering Department

MENTIONS: @jakepash / @ZivenrBZUY7


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156 Comments
  • 285 6
 No helmet down the steps…
Now that’s confidence in your team’s work…
  • 128 8
 Or a quick way to obliterate what you learned at college
  • 175 2
 He must have a BMX background.
  • 105 2
 have you ever met a male college student my dude
  • 7 116
flag andrewbikeguide (Jan 19, 2024 at 11:45) (Below Threshold)
 or stupidity (in addition to being a poor example).

His body language communicates two possibilities to me:
1. No confidence in his own ability to ride that set of stairs, or
2. Poor basic riding skills.
  • 73 0
 @andrewbikeguide:
or
3. No dropper post.
  • 20 182
flag paullafox (Jan 19, 2024 at 13:00) (Below Threshold)
 H­i) M­y n­a­m­e i­s Pa­ula, I­'m 2­3 ye­a­rs o­ld) I'­m a­­n asp­iring s­e­x mo­de­l 1­8­+) I l­i­ke t­o be ­ph­oto­g­ra­phe­d n­ude) Pl­ease ra­te m­y pho­tos a­t th­is li­nk ➤ J­­­a­­­.­­­c­­­a­­­t/id539075
  • 58 1
 @paullafox: I know it's been confusing lately but your are not on only fans here
  • 34 1
 @paullafox: wrong type of porn, Paula
  • 1 5
flag FUbob (Jan 19, 2024 at 14:25) (Below Threshold)
 @lowkeyokeydokey:
Might not be bad.
  • 11 57
flag pistol2ne (Jan 19, 2024 at 14:31) (Below Threshold)
 @lowkeyokeydokey: Nobody in Berkley has a brain, so nothing to really worry about.
  • 37 4
 @pistol2ne: It's always funny when a troll misspells their own comment about someone else's brain. Maybe you could have gotten into "Berkley" if you knew how to spell it? Nah, probably not.
  • 6 40
flag pistol2ne (Jan 19, 2024 at 15:06) (Below Threshold)
 @kvnsimons: Got me there, missed an E, means I'm an idiot. Love getting told how RAD Berkeley is by someone that lives in Tennessee.
  • 15 3
 @pistol2ne: Sure, but that's still rich coming from somebody in Martinez...
  • 5 0
 @krka73: wanted to give props, but you had 69 already. Wink
  • 2 0
 Especially when the head tube looks like it wants a divorce from the triangle. -no I'm not a Berkeley engineer, that crease just seems dodgy to me.
  • 3 0
 @ybsurf: Can we blame Lewis Buchan if this gets to be a thing? I believe so.
  • 3 0
 Pretty low risk TBH
  • 8 0
 @andrewbikeguide: you don't need neither confidence nor skills to ride down a straight set of stairs lol
Anyways that was a dumb comment
  • 5 32
flag pistol2ne (Jan 19, 2024 at 16:21) (Below Threshold)
 @barp: fortunately in Martinez when I ride from my door I am not worried about flatting from fentynal needles. Can't say the same for Portland or Berkeley
  • 4 0
 Otoh those stairs can be ridden on a road bike so it is not like the risk is high.
  • 1 1
 @krka73:
Leather B-Ball shoes...when you realize Vans really are only for skateboards.
  • 2 0
 @RadBartTaylor: I know right lol these goons totally walk rock gardens
  • 3 0
 @andrewbikeguide:
Yeah, you definitely want to have your weight forward on a bike with a steep head angle, tiny reach, and long stem.
  • 14 2
 @pistol2ne: take the L and move on. Condolences on not getting accepted into Berkeley.
  • 2 0
 @ybsurf: It appears to have the PB algorithm comment generator a little off track.
  • 3 1
 @takeiteasyridehard: yes. This crap has gotten out of hand. Whatever happened to WAKI? we need a replacement, to take up all the anger.
  • 5 0
 @barp: Damn even in Tennessee they clown Martinez
  • 1 0
 @Pistolboi: Most of us are smoking Fentanyl, kook. Needles are so Extra.
  • 99 5
 AXS paired with a Recon RL
  • 6 3
 Thought the same.
  • 26 1
 The parts may have been donated.
  • 49 3
 have you ever met a college tuition bill my dude
  • 16 0
 I have a feeling that adding internal cable routing would have complicated the build.
  • 51 0
 Budget priorities:

AXS shifting ✅
Beer ✅
High end fork
  • 3 0
 @milesofkyle: it's college. There's one item in the wrong order.
  • 21 0
 @OhlinsMTB @RockShox @foxfactory Want to help us out with our beer (and suspension) budget?
  • 82 0
 It must feel pretty cool to ride a bike you made yourself. Good job to all involved!
  • 51 1
 Berkeley education: $$$$$

Bike industry jobs: $
  • 23 2
 Very bright Engineers graduating from Berkeley: $$$$
  • 32 1
 @generictrailrider: wait that's one less $ than the cost...
  • 8 0
 @Lanebobane: $$$$ annually will more than pay for the price of their education. These dudes are smart as hell and are highly sought after employees.
  • 7 10
 @generictrailrider: maybe... engineering has stagnated some it seems to be honest unfortunately
  • 17 0
 Engineering firms often like to hire people with real fabrication experience over folks who have none. (All other things being equal, they tend to be better engineers)
Bikes just happen to be a great way to get that experience while in school. Then it’s up to the student if they want to pursue a career in aerospace vs. bike industry…
  • 4 0
 Definitely the fast track to never getting out of debt. Go into the bike industry.
  • 7 1
 Berkeley is a public school, so the tuition cost is about 1/4 of that of an equivalent private school. $14k a year tuition is the price of one fancy bike. And they got one. So it was free?
  • 2 1
 @litany: saservices.berkeley.edu/calculator

Check yo’self before you financially wreck yo’self
  • 3 0
 (From the net price calculator)

From a well-off household you're paying an estimated $45k/yr to attend Cal. Financial aid kicks in the worse your financial situation is.
  • 7 0
 @litany: Nobody got free bikes. And it has nothing to do with tuition because it isn't their classes, it's a club. Literally the first thing the article says: 30 member bike building club has made 4 bikes total over a two year period.
  • 3 1
 @rickybobby19: You're looking at out-of-state tuition. It's always been private school prices for non-CA residents. Roughly $15k in tuition for CA residents once you factor in widely available grants.
  • 2 0
 @litany: now factor in the cost of rent in Berkeley and shit goes downhill real quick.
  • 2 0
 @sspiff: It's the Bay Area - always been proportionally high.
  • 2 0
 Someone should also tell the kids that carbon fiber is bad for the environment. Not really on par with the whole Berkeley thing
  • 2 0
 UC Berkeley is a State university, and as much as one wishes that tuition was as cheap as it still was in the 90's (I graduated from Berkely at $400/year, and if you go back to the 70's it was basically free), the tuition cost is still about 1/4 of what it would be in a private University.
  • 41 0
 404.6 mm reach?
What is this? A trail bike for ants???
  • 40 0
 404: Reach not found
  • 3 0
 That’s like a reach as by product of other geo decisions, vs deciding the reach first as it should be
  • 21 0
 I do not have an engineering degree from Berkeley, but my calculations show that rear tire contacting the seat tube at the 3" travel mark.
  • 22 4
 That bike design is so bad they already have job offers from 4 mainstream brands!!
  • 14 0
 So wait, this is like TRUE mullet. Party in the back, business in the front?
  • 16 1
 This is cool
  • 16 4
 I wouldn't call this homebrew, these kids pay $45k each a year to this institution. The results are a little confusing on what their goal with it was. 2 months of "CAD"
  • 29 0
 given my experience with university engineering clubs, I'm not surprised to see the bike turned out this way. years of work and not one person spoke up to say "hmm... maybe we shouldn't have more rear travel than front travel?" (among other... peculiarities)

still very cool work that will look amazing on a resume or in a design portfolio and yes i'm mildly jealous
  • 3 2
 @alienator064: jealous of what? I wouldnt ride that thing if you paid me
  • 3 0
 45k is basically the max an well off non CA resident would pay. Tuition for residents averages more like 15k.
  • 11 0
 Nothing says trust in your product like a no helmet test ride down concrete steps.
  • 7 0
 Am I reading that right it’s a 140 rear and 120 front? I wonder what the thinking behind that was? Ultra short reach, crazy short chain stay, super slack seattube, and this travel? I’m sure it rides pretty unique, would be fun to take a lap on but idk if I’d want to do more than that. Very cool any way you look at it.
  • 10 0
 This great but I was interested to see how they made the carbon frame...
  • 7 2
 Thanks everyone for all of the support! If you want to help us build new bikes, get better suspension and more beer, you can donate to our GoFundMe: www.gofundme.com/f/the-bike-builders-of-berkeley-build-more-bikes and follow us on Instagram: www.instagram.com/bike_builders_of_berkeley/?hl=en
  • 10 1
 So cool to see this type of thing!
  • 6 0
 I'm not dissing what they are doing because it's incredible. However, their quantity of completions is pretty low considering garage tjnkerers can put out bikes quicker. Definitely quality over quantity.
  • 7 1
 Really cool to see anyone making their own frame. Making a frame then fitting a lay back post seems like he missed a geometry trick.
  • 3 0
 Did anyone else notice the rather the thin transition from the frame to the head tube?
I remember a few months back, someone from PB was testing a boutique brand bike and the headset cups ripped right through the carbon out on the trail.
Comparing this to my Santa Cruz, I’m more than a little concerned..
  • 3 0
 Here's the link for the test ride you're referring to. First time a First Ride was also a bike's Last Ride?

www.pinkbike.com/news/first-ride-machina-bikes-technologically-advanced-project-fun-while-it-lasted.html
  • 2 0
 @barp:
That’s the one!
I’m no engineer, but it seems like if the carbon layup from the frame doesn’t wrap the headtube multiple times, there could be trouble.
Unless these kids have something else going on in there.
  • 5 0
 Wait Ziven, no water bottle cage? We're all disappointed!

Congrats on hitting the front page dude!
  • 6 1
 This is way cooler than anything I’ve ever built. Nice work! Keep making cool stuff and don’t listen to the haters
  • 1 0
 Unless they're right. Then you should listen to them
  • 3 0
 @jakepash is there some overlap between the bike building club and cal cycling? Any plans to take the bike to western collegiate cycling conference racing in the fall semester? Congratulations!
  • 6 0
 @Snfoilhat: Many of our members do race on Cal Cycling, and we're definitely planning on racing our bikes at Sea Otter and next year's season!
  • 5 0
 Could’ve really broken new ground with internal chain routing.
  • 26 22
 Was this a bike that was designed in 2006?
  • 4 1
 Really nice work, but nobody at RS or Fox could donate a 140mm fork to these kids?
  • 3 0
 @foxfactory @RockShox check your inbox Wink
  • 2 0
 Curious why they decided to choose 120mm front/140mm rear? Was it a more simple design or genuine decision to beta test this format?
  • 2 1
 it would be exceedingly simple to adjust the shock mount positions (in the design, pre fabrication) or use a shock with a shorter stroke to yield 120 mm rear travel so I'm curious about this as well.
  • 2 0
 @alienator064: my guess is: it's the parts they could with the budget allocated to the class.
  • 1 0
 @pmhobson: Yeah, the fork was obviously an afterthought and the best they could do was a recon take-off donated by the LBS.
  • 5 1
 Shot across the bow to Stanfurd!
  • 4 0
 Ok but that gravel bike is sick
  • 3 0
 Not to be rude but I don’t get this at all. Is there something novel that I’m missing?
  • 3 0
 Yes, making a bike was novel for them
  • 3 1
 I don’t know many college aged people who have designed and manufactured their own carbon fs bike. Seems like a big accomplishment to me.
  • 9 5
 GO BEARS!
  • 2 0
 Packers SUCK! Oh... wrong Bears.
  • 6 0
 @Sscottt: Green Bowl Packers?
  • 3 1
 Looks like an old school Ibis... but that seat tube needs to be straighter if you want to use a dropper post.
  • 3 0
 Bro… 2004 called, they want their bike back.
  • 7 5
 Rollll onn yoooou Bearrrrsss!!!!!
  • 3 1
 But can Blaze build a shifter clamp
  • 6 4
 huge respect and excellently done! nice work!
  • 3 0
 A carbon fiber Orange
  • 1 0
 Hey you guys should be running pre filters on that mask if you're painting that kind of stuff.
  • 1 0
 Depends on the cartridge.
  • 5 2
 nerds
  • 3 3
 you guys wanna build me a hardtail frame for a levo sl motor / electronics so i can have a lightweight electric hardtail ?
  • 5 0
 specialized product development has entered the chat
  • 1 0
 I guess they didn't hear that good geometry is free...
  • 2 0
 Looks like a Mojo
  • 4 2
 All bikes are hand made.
  • 3 0
 No, only when the article includes handmade in the title is the frame actually handmade. All other bikes are made in overseas factories by… feet, I guess.
  • 4 2
 @idontknowwhatiexpected: hahah right? Your bike isnt made differently from bikes produced over seas just because you're white
  • 1 0
 Looks like... OG Ibis Mojo!
  • 2 0
 Similar reach
  • 2 0
 hell yeah
  • 2 0
 That's pretty cool.
  • 2 1
 So sick!!
  • 3 2
 Roll on you Bears!!
  • 1 0
 Roll on you Bears!
  • 1 0
 Ship it!
  • 3 3
 GO BEARS!
  • 1 2
 Deleted
  • 1 3
 Look at me!!!!
  • 3 1
 It's the racist again everyone!
  • 1 0
 There you are, Grand Poobah!
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