Homemade Bikes: The Gorilla

This weeks homebrew bike is a stainless steel eight inch travel downhill beast called the “Gorilla”

Yann Watkins built the Gorilla back in 2008 and is working on the mark two version now (the Orangutan?)

Anyway enough of the monkey business here’s Yann top tell us about the bike:

My name is Yann Watkins and I am a Product/Industrial Designer with a passion for bikes. I did some design work related to the bike industry in the late 90s early 00s. Then I moved to Chile, were I am currently located right now.

The Gorilla

I designed and built the “Gorilla” because I wanted a downhill bike that would pedal like a hardtail. This is achieved thanks to its jackshack configuration and internally geared hub. The lack of a rear derailleur, a non extending chain, a jackshaft double chain system and high pivot location proved to be a winning combo. It carries speed and pedals like no other bike, it certainly doesn’t feel like an 8″+ rear travel bike when you pedal.

The linkage

I used to own a metalwork shop and I built the bike overnight when the machines weren’t being used (and kept working during the day) thus the dull mobile phone pictures.

All of the machining has been done on old fashion mills and lathes (hard but very rewarding) including the linkage and head tube.

Bits and bobs
The bare frame

The head angle, bottom bracket height, chainstay length, rear travel (6.7 to 9.5), shock compression rate, shock size (it can take 3 different shock lengths: 220 – 230 – 240) are adjustable.

Cogs

Some Geo:

Wheelbase : 110 / 113 cm
Chainstay: 40 / 43 cm
Bottom bracket height: 35 / 39 cm
HA: 65 / 67
Shocks: 220 / 230 /240 mm
Frame weight w/o shock: 4.6 kg

Rear drop outs

The Gorilla is completely build in stainless steel, except the linkage mechanism that is made of 7000 series aluminum. The bike is extremely stiff.

The Gorilla

Downside: complete it weights around 19 kg. it feels heavy compared with newer dh bikes

It is currently fitted with and Shimano alfine 8 hub. (A wonderful piece of engineering)
- old school suspension pack: a fox vanilla rc at the rear and a 1998 DDG floozy forks – sometimes I used a de-gutted heavily modified RST R1, great chassis crappy interiors)

The bike was finished in 2008, so it is getting old now but it’s till going strong and thanks to its huge adjustability the geometry it’s not that out of date. Weight though, that’s another story!

I will soon start work on another the “evo” so stay tuned for that!

Have you built your own bike frame? Yes? Then get in touch with Billy

  1. MuSkA

    Well I honestly though that beast would be heavier! 19kg it´s not bad at all for a homemade bike with internal gearing, etc…

    Put some nice updated bits on that and the weight will drop in no time and you´ll have a unique and up to date bike!

    Well done, loved it

  2. Djmak

    Takes some doing that. Mint!!

  3. Djmak

    Takes some doing that, i just wana know how the Gorilla rides. Mint!!!!!!

  4. Si

    Madness!!!

  5. Rick

    Those linkages look awesome! Wish I had access to a machine shop…

  6. Big Bird

    Making those linkages on a manual mill is very impressive. Far more set up work than actual machining. I wonder though about the use of stainless steel for the frame tubes as it’s so easy to bend. Some thinner walled chromo tubes would make it lighter and stronger. I do like the jack shaft action. As I was typing this, I had the idea to use a belt drive system with the jack shaft to eliminate some of the weight of all that chain.

  7. Morpheous

    Nice work for sure, jackshaft is good. the main detriment is having a 4Lb hub on the end of the swing arm though. This seems to me to be a predecessor of the Zerode design from New Zealand? (they moved the hub inboard)

  8. philip

    Good effort.

  9. Onion

    good idea with the stainless – save loads of weight by not painting it eh?…..

    Amazing. Would love to build my own bike [that worked]

  10. BenPea

    Those wheels can’t help the weight either…

  11. centrifuge

    Billy, Please check your punctuation before posting.

  12. centrifuge

    Nice work Yann Watkins. It is the best bike featured here yet! The angles look good.

  13. Leon

    What an awesome bike man !
    19 kilos is well respectable considering its steel and built with heavy parts , you have done really well in my opinion ( worthless opinion maybe ).
    Get some Saints on it and upgrade your rims you will loose a fair chunk of weight .

  14. Churchie

    Wow, good work! Centrifuge, you used a capital letter mid sentence, please check before posting….(!)

  15. ross

    what ever happened to the millward racing bike? it was amazing!

  16. centrifuge

    I used a capital P for dramatic effect. I’m not publishing articles or write-ups on the internet. Billy is. In addition, I posted a complement for Yann Watkins but, I guess you don’t like complements or his handmade bike because you negatively noted it too. For the sake of reason and quality of execution in what you do, please proofread before posting as it is the least you can do for Yann and his quality bike. After all, It’s your job!

  17. billy

    Sorry centrifuge, it was a bit of a rush job. Will try harder next time.

  18. centrifuge

    No need to say sorry. I just get a little wrinkled when people sensor reason. I make a lot of spelling mistakes so, I have to check frequently to avoid potential brain damage. I really do appreciate what you boys and girls do at DirtMag however, I am sick and tired of this ubiquitous mob attitude that is infecting MTB-ing.

  19. bacon

    Interesting to see how many of these home-made bikes (I’m including the Millyard in this) use some sort of gearbox, or means of achieving a workable higher pivot point (+backward axle path). Only the Zerode (which I believe started as a home-made) and K9 appear to currently be taking this into production though…?!

X

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