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PostPosted: Sat Mar 31, 2012 7:12 am 
retrobike rider / Gold Trader
retrobike rider / Gold Trader

Joined: Thu May 07, 2009 6:42 am
Posts: 1517
Location: Mostly West Midlands
titch__16 wrote:
I always considered pedal bob to be fixed by a better shock. I also read about the Klein Mantra eliminates this, so I'm trying to think of a way to incorporate it.


Klein Mantra are a URT design, meaning the whole rear triangle (crank/BB included) is not suspended, therefore no change in BB-Rear axle length as the suspension compresses.

Benefits and limitations of URT designs have been discussed endlessly on various forums, but there's a reason why most suspension designs have moved away from it.


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PostPosted: Sat Mar 31, 2012 8:07 am 
Retro Guru
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Joined: Wed Dec 14, 2011 2:27 am
Posts: 454
Location: Brasov, Romania
If you ask me, this "What is the best type of suspension?" discussion is kinda like "What is the best car in the world?", "What is the hottest chick?" or the classic "My dad beats your dad". There just isn't something like that. There are much too many variables when it comes to rear suspension. Imagine just how different two hardtails can be and how it's not quite easy to judge what the best is. And they are "only hardtails"... Okay, now add 20+ variables and try to decide! Easy task, right?

I really don't know how you'd replicate the Manitou FRS system for a more modern bike with 150 mm or where you would get that suspension struts from. If you are serious about building your own thing, look around for popular and proven designs around 150 mm, ride them, find out which you like best and try to replicate it. There are a lot of simple yet effective bikes with good geometry out there. Think Orange, think Specialized etc. It's all about geometry, about shock rates and about the quality of suspension and it matters less if the shock is horizontal or vertical.

I am sure there should be several test centers on various events and other occasions where you could try out some bikes and figure things out.

Cheers,
Mx


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PostPosted: Sat Mar 31, 2012 9:16 am 
Retro Guru
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Joined: Mon Feb 07, 2011 1:14 am
Posts: 1871
Location: Kuranda DH circa 1991
Lid wrote:
merckx wrote:
Trek 9000. Best suspension design ever,period. just do it.


Your joking right? This bike generally comes top of the list for worst ever suspension design.


correct :D


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PostPosted: Sat Mar 31, 2012 11:35 am 
Retro Guru
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Joined: Fri Dec 02, 2011 11:17 am
Posts: 469
Location: Northern California
Doesn't the whole 'lefty' front 'righty' rear suspension thing tend to lead to uneven (and thus quicker) wear at the pivots?


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PostPosted: Sat Mar 31, 2012 12:15 pm 
Special Retro Guru
Special Retro Guru
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Joined: Mon Sep 29, 2008 11:34 am
Posts: 5663
Location: Don't mess with monkeys, man
ChuckO wrote:
I'm not an engineer

Bloody hell, you must be the only member, here, who's not.

Well there's you... and me makes 2.

S'almost like the stonecutters in here!


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PostPosted: Sat Mar 31, 2012 12:31 pm 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
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Joined: Sun May 25, 2008 11:03 am
Posts: 18207
Location: Sunny Glasgow
Neil wrote:
ChuckO wrote:
I'm not an engineer

Bloody hell, you must be the only member, here, who's not.

Well there's you... and me makes 2.

S'almost like the stonecutters in here!



:lol: :lol:


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PostPosted: Sat Mar 31, 2012 12:38 pm 
Retro Guru
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Joined: Fri Mar 12, 2010 1:17 am
Posts: 634
Location: New England
Other 'Classic' designs/methods:

'96 Ted Wojcik (I have lots of pics of the rear triangle construction if you are interested:
Image
Image

'95 KHS:
Image

'97 Univega:
Image
Image

I'm a firm believer in 'reinventing the wheel'. Good luck.


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 Post subject:
PostPosted: Sat Mar 31, 2012 4:25 pm 
Dirt Disciple

Joined: Sat Oct 16, 2010 7:29 am
Posts: 36
Location: California
shogun700 wrote:
I'm a firm believer in 'reinventing the wheel'. Good luck.


Heh. When I first read the original post, it reminded me of the documentary "Plane Crazy" of a few years back, in which tech writer Robert X. Cringely endeavors to build his own airplane (or "aeroplane", if you will). Not only does he give himself a ridiculous deadline, he also thought he'd "reinvent the wheel" while he was at it.

Envisioning himself as Burt Rutan or something, he was going to fabricate the plane out of carbon composites and locate the engine in the middle of the fuselage, with the prop driven by a drive shaft. A great concept because it balances the weight distribution, but there are reasons why this great concept hasn't flown.

By the time his deadline arrives, he's partially completed the layup of one wing. In the process, he's nearly suffered a nervous breakdown and has pissed off everyone around him.

Giving up on his reinvention of the wheel, he eventually goes to some family operation in Kentucky or somewhere like that, and ends up building a wood & fabric, VW-powered biplane... in a couple of weeks.

Anyway, with that cautionary tale in mind, I heartily encourage the OP because the stakes aren't quite as high as in building an airplane. Just be willing to alter your design to conform to physical realities, and don't be surprised or upset if it ends up being much closer to conventional designs.

BTW, have you designed and built non-suspended bikes before?


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PostPosted: Sat Mar 31, 2012 5:06 pm 
Old School Grand Master
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Joined: Sun Sep 05, 2010 1:10 am
Posts: 4756
Location: Heathfield, East Sussex
Hasn't there been a similar looking bike posted recently that used a monocoque chain stay with the shock on the opposite side??


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 Post subject:
PostPosted: Sat Mar 31, 2012 6:20 pm 
Gold Trader / MacRetro rider
Gold Trader / MacRetro rider
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Joined: Sun Apr 02, 2006 1:03 pm
Posts: 11796
Location: Returning
how are you going to brake the rear wheel ?

the lefty righty stuff is all well and good, and cannondale and others
have done the front end very well ,but you need specific wheels
and therefore hubs for them
it all depends what your trying to achieve here
a uni engineering project or just dicking around on solidworks ?

if you look at off-road motorcycles you'll notice that they all look
pretty similar and have done apart from styling for the past 30 years
why ? cos they work
an mtb is in the same vien ,a simple single pivot as per the previously mentioned orange 5 etc is all you need
if you want complex do a 4 bar link like a gt lts or a giant x2

whatever your doing keep doing it


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