Downhill bike Ive been building...

[MonsterMetal]

Hey guys... This is a purpose built downhill machine that Ive been working on. I custom built the bottom bracket with a 4 bearing set up so the swing arm pivot is such that there is zero chain growth. Its all 4130 ch moly.. The bike is the brain child of my friend Troy and we have been working on it for the last few months... Pretty exited to have it looking like a bike!! Tonight was the first night we had all the parts together and its looking like its gonna be great! Single speed gear train with no derailleur makes the thing bulletproof bombin down the mountain...

 

[thatismytruck]

I like very much!! good welding there too. I'd like to see a better photo of the pivot point behind the chain ring. Do you have one?

 

[aka_locojoe]

I'd like to see a better photo of the pivot point behind the chain ring. Do you have one?

Me too.

Nice job.

 

[ifitsfreeitsforme]

shweet! bolt a vid cam to that puppy and show us some downhillin

 

[fast eddie]

im a big fan of rolling down hill!! sweet work man, that thing looks tough!
fast eddie

 

[SkidMark]

I've never understood why every mountain bike isn't like this, it seems so obvious (once you think of it). Make the swingarm pivot the same as the bottom bracket!

 

[MonsterMetal]

Ok... Here are some close ups of the bottom bracket and pivot..

 

[Hooch]

dude you have some major skills!

 

[thatismytruck]

That pivot is sweet. Nicely done.

 

[MadMick]

Nice job. Do you have some falling-rate rear shock pivot location geometry going on there?

 

[MonsterMetal]

yep... sure do. Not my department though. Troy has this thing all figured out in a cad program and did all the computer modeling. Im a more by the seat of your pants kinda guy but its sure nice to have someone with some design savvy figure all that stuff out so it works right the first time... Its pretty stiff for a downhill bike but Troy is a big guy... so its probably not so stiff for him.

 

[user 135]

That is very cool. So there is a bearing on each swing arm and 2 in the BB? I wonder why the manf. have not tried this.

Do you have plans to build one with some Chromoly tubing?

 

[thatismytruck]

That is very cool. So there is a bearing on each swing arm and 2 in the BB? I wonder why the manf. have not tried this.

I imagine it would be expensive to tool up for that in mass production which would make it too expensive for retail. I bet he could get a fair number of hard core people to buy a custom frame though. A one or two guy team such as they have could make a little money on the deal.

 

[MonsterMetal]

That is very cool. So there is a bearing on each swing arm and 2 in the BB? I wonder why the manf. have not tried this.

Do you have plans to build one with some Chromoly tubing?

Yep... 2 in the BB and one on each side... And this is a full chromoly frame....

 

[MonsterMetal]

That is very cool. So there is a bearing on each swing arm and 2 in the BB? I wonder why the manf. have not tried this.

I imagine it would be expensive to tool up for that in mass production which would make it too expensive for retail. I bet he could get a fair number of hard core people to buy a custom frame though. A one or two guy team such as they have could make a little money on the deal.

Yeah.... I dont know If I personally could make any money building these... Maybe if I farmed out the machine work to a CNC shop...
It took 10 or so hours to machine the bottom bracket/pivot parts... another 4 or 5 for the drop outs...15 or so hours in fitting all the frame tubes... probably 4 or 5 to weld it... maybe $300 worth of materials So we are talkin $3500 without a shock? I suppose that's not to far out of line for a big name custom built frame... but Im just some yahoo...

I built this bike for free... looked like a fun project and Troy.. the guy who designed the bike... is just a heck of a nice guy.... He did take me to lunch the other day..and did a fine job sweeping while I was welding up the swing arm...

If you where going to build 10 the time required per bike drops way down.. assuming they where all the same size that is... But really to me its only fun to build one. (or maybe 2 :wink: ) Id rather build one for free than 20 for $2000 each.... I make pretty good money doing my work stuff so the last thing I want to do is turn my hobby into work....

 

[bicycleguy]

That bike is awesome, it looks like a single speed slopestyle bike.

 

[dumpster_diver]

Got any updates on this bike? Bad to the bone!

 

[tartosuc]

I've never understood why every mountain bike isn't like this, it seems so obvious (once you think of it). Make the swingarm pivot the same as the bottom bracket!

pivot placement makes a big difference is the way the bike reacts when you pedal it and when you ride it (pedal feedback, brake jack etc). Every pivot placement has its own advantages/disaventages ... afew mm up/back/forwared etc can make huge difference in the ride carateristics.. I've been riding Downhill/cross country suspended bikes for over 10 years now.. I had a lot of simple pivot bikes and they had all different riding carateristics du to pivot placement. ther are also the multi pivot bikes, wich i could explaned for hours...

 

[Galtbacken]

... but Im just some yahoo...

No, Monster, you're not fooling me!! That bike is beyond words!! :shock: Amazing work you've done there!!!

 

[user 135]

I've never understood why every mountain bike isn't like this, it seems so obvious (once you think of it). Make the swingarm pivot the same as the bottom bracket!

I guess someone is trying.
http://www.pinkbike.com/news/commencal- ... -2010.html