# Pull Shock frame...not another FS design



## yogiprophet (Jan 9, 2006)

I have spent many hours evaluating all types of suspension designs with the linkage program. When I tested them on equal footing (definition below) what I found was that when I tweaked each design so the pedal feedback was the same for each one, the axle paths for each design were very nearly the same. The difference in rearward extensions was no more than about 2mm for 130-150mm travel. The VPP was the only design that had a significantly different path, but it also did not have anything better to offer as far as pedal feedback. Note: the axle path of the new 2008 version of the Blur LT now has an almost circular path. They apparently decided that the pedal feedback in the small ring of the models before it was too much of a sacrifice. The pre 2008 BLT and other current VPP Santa Cruz and Intense models have more pedal feedback than any other popular design.

By equal footing I mean the bottom bracket height in relation to the rear axle height at full extensions were all the same.

Kirk Pacenti mentioned that Pull shocks are making a comeback, and so I sketched this up last night. This design uses a Rohloff hub and a left side cog on the crank that runs a cog on an axle through the swingarm pivot (belt driven would be sweet). It is a negligible pedal feedback design that relies on the forward force of the rear axle times the sine of the angle between the horizontal and the swingarm to counter squat. The relation on the location of the center of mass, the force applied and the angle of the swingarm need to be evaluated and changes with each individual and trail situation. For this and other variables, I am a believer in adjustable pedal platform.
This design also had plenty of rear brake squat which I am a fan of; others may not appreciate it.

Mountain biking is all about maintaining momentum. Rear axles of full suspension bicycles move in an approximately vertical path. The I-drive appears at first to move in a rearward path, but the bottom bracket also moves rearward and upward countering the rearward movement of the axle. If you think about a front fork being oriented vertically, (from a bump absorbing standpoint) it would not be as adequate in absorbing the energy of an impact for obvious reasons having to do with momentum. Of course this is not the first design of this kind – only another variation. I am thinking that the additional mass (of the rear hub at least) may be more than compensated for by the momentum saved by a much more rearward axle path (which is similar to the front axle path) and the pedaling efficiency of negligible feedback. The pull shock design adds lateral stiffness, and is very cool also. It appears to have a very linear leverage ratio.

I would like those of you who are interested to add or critique.


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## dr.welby (Jan 6, 2004)

yogiprophet said:


> I am thinking that the additional mass (of the rear hub at least) may be more than compensated for by the momentum saved by a much more rearward axle path (which is similar to the front axle path) and the pedaling efficiency of negligible feedback.


Food for thought with a rearward axle path. If you think you are saving momentum by letting the rear wheel travel backwards relative to the rider, remember you have to accelerate the wheel back up towards the frame so that it can catch back up with the frame on rebound. From an energy standpoint, there might not be a free lunch here.


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## playpunk (Apr 1, 2005)

I think that your design, by definition, can't use a rohloff and a belt drive. Any "chain growth" at all wouldn't work for a belt-drive bike. The Scott Genius bikes use a pull shock - a nice looking design, if you ask me.


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## chequamagon (Oct 4, 2006)

playpunk said:


> I think that your design, by definition, can't use a rohloff and a belt drive. Any "chain growth" at all wouldn't work for a belt-drive bike. The Scott Genius bikes use a pull shock - a nice looking design, if you ask me.


read again, you missed it. driveline would be along axis of dropout to pivot. zero chain growth.


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## Acme54321 (Oct 8, 2003)

Since when are pull shocks making a comeback?


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## pvd (Jan 4, 2006)

Pull or push shock makes no difference in fundemental design. It is a simple housekeeping issue.

Your frame in the sketch has way too much anti-squat. It's one of the worst single pivot designs i've seen in a while. Only a little anti squat is needed and the design you show has about 400x too much. There is a very good reason why single pivot bikes (like you have shown) use a pivot aproximately between the middle and large rings. Yours is about 9 inches away from that. Totally out of the ballpark.

Also, from a mechanical point of view, you are driving side forces into the shock. Amature at best. The shock needs to be free of any but axial loads.


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## yogiprophet (Jan 9, 2006)

pvd said:


> Your frame in the sketch has way too much anti-squat. It's one of the worst single pivot designs i've seen in a while. Only a little anti squat is needed and the design you show has about 400x too much. There is a very good reason why single pivot bikes (like you have shown) use a pivot aproximately between the middle and large rings. Yours is about 9 inches away from that. Totally out of the ballpark.
> 
> Also, from a mechanical point of view, you are driving side forces into the shock. Amature at best. The shock needs to be free of any but axial loads.


Pull shocks are designed to withstand side loads pvd.

As far as anti-squat, mabey I should have drawn the chainS. This is not a typical single pivot design here - nothing revolutionary either. The chain from the crank drives a gear centered on the swingarm pivot(on the left side of the bike). Another gear on the other side of the swingarm pivot (the right side)drives the gear on the hub. Niether chain needs a tensioning device nor do they stretch at all. The drive chain DOES NOT produce anti-squat.

Think of it being like the old Klein Mantra, but the BB is stationary. It would have less anti-squat than the Mantra because the pivot is lower. The downhill quality would be much better than the Mantra also.


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## brant (Jan 6, 2004)

chequamagon said:


> read again, you missed it. driveline would be along axis of dropout to pivot. zero chain growth.


Ah - I was going to say that zero chain growth = zero anti squat, but you're using the thrust reaction from the rear wheel to combat that. I get it. That's quite neat. Lot of engineering (and weight) in that geared crossover drive though (and the weight is quite high up).


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## D.F.L. (Jan 3, 2004)

I think you should build it. Jackshaft bikes are criticized for the additional weight and drivetrain drag. The weight could be managed if you're willing to pay close attention to design. Drag? Dunno, never tried one.

Forget the pull-shock. I know of nobody making one and your design could work just fine with a conventional model mounted vertically.

The whole idea that mass must be kept as low as possible seems like a myth to me. When you make a quick direction change on a bike, the top of the bike does not make a big change in direction. The greatest movement occurs at the tire contact patch and the rest of the bike pivots around a point near the rider's arse. This was discovered many years ago in road race motorcycles when efforts were made to create the lowest CG possible and the bikes were slow to turn.

I think that the magazines look at a bike and if it appears to have a low CG, then they observe the characteristics their minds are expecting.


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## TacoMan (Apr 18, 2007)

The dynamics of the chassis would still create a lot of anti-squat it would just not have the added chain tension.

Putting side loads on a shock is not good even with a thru-shaft. You don't want to have variable friction added to the damping.


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## patineto (Oct 28, 2005)

I explore similar ideas for my new tandem project and i even made a posting asking about *High Pivot frames* on the "shock" section of this forum.

one of the many drawings.









sadly I don't have sufficient understanding, at least compare to some of you, so I'm stuck trying to solve every problem at ones.

Will be great to see the outcome of you project, to gain a better understanding.

Oh.....
this other posting on *IBIS Tandem* evolve into a really nice conversation that may be useful for your project.


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## Clockwork Bikes (Jun 17, 2006)

*Striaght 8 Copy*

I've been very happy with the Yeti/Schwinn Lawwill pull-shock design. This bike was a bit of an experiment, I bought a Straight 8 and used the rear end for my front triangle design.

www.clockworkbikes.com/8.html
















-Joel


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## pvd (Jan 4, 2006)

yogiprophet said:


> Pull shocks are designed to withstand side loads


You're kidding, right. Shocks should never be treated in any way other than compression or tension. Putting a side load on one just binds up the shock and slowly destroys it. Forks are a special case where we put up with the inherent problems of doing this because all of the alternative designs produce even more problems. In the rear, only bad engineering relys on the shock for stucture.



yogiprophet said:


> The drive chain DOES NOT produce anti-squat.


I guess I missed the jack shaft in the drawing. So, this is a simple (very) high swingarm with a jackshaft concentric with the pivot. Those are the terms that would best describe your design. In this case, drive forces will produce negative anti-squat. Said otherwise, under power the bike squats.

This bike would be horrible for anything other that big game free hucking. That assumes that every detail was worked out perfectly. It really has no use as an XC or DH design.


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## brant (Jan 6, 2004)

pvd said:


> You're kidding, right. Shocks should never be treated in any way other than compression or tension. Putting a side load on one just binds up the shock and slowly destroys it. Forks are a special case where we put up with the inherent problems of doing this because all of the alternative designs produce even more problems. In the rear, only bad engineering relys on the shock for stucture.


Perhaps he meant that some pull shocks are Rose/Spherical Jointed. I've seen ones that are.



pvd said:


> drive forces will produce negative anti-squat. Said otherwise, under power the bike squats..


I disagree 100% - though I've not had enough to drink today.


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## yogiprophet (Jan 9, 2006)

dr.welby said:


> Food for thought with a rearward axle path. If you think you are saving momentum by letting the rear wheel travel backwards relative to the rider, remember you have to accelerate the wheel back up towards the frame so that it can catch back up with the frame on rebound. From an energy standpoint, there might not be a free lunch here.


No free Lunch! Don't tell a mountain biker that  
Seriously though, I would have thought the suspension would naturally go back to the sagged position. The front fork has a rearward path and it goes back to equalibrium after hitting a bump.


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## yogiprophet (Jan 9, 2006)

[email protected] said:


> Perhaps he meant that some pull shocks are Rose/Spherical Jointed. I've seen ones that are.
> 
> I disagree 100% - though I've not had enough to drink today.


The K2 race bike I had in 2000 had a seatstay pull shock that carried all the load that the seatstay had to offer. It appeared to have a sliding bushing on the shock shaft. Worked very well; never needed lube.

I may need to drink more too, but I agree 100% with your 100% disagreement. It depends on the chainring arrangment between the upper (swingarm) gear and the hub gear.


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## pvd (Jan 4, 2006)

yogiprophet said:


> It depends on the chainring arrangment between the upper (swingarm) gear and the hub gear.


No. Any bike with a drive sprocket mounted concentric to it's swingarm pivot MUST produce negative anti-squat forces under power. Any gear you choose will do it. Do you understand this concept at all?

Any good design will have some postitive anti-squat in the drive system to counter the rearward pitch (thus squat) under acceleration. The net should be some squat (for improved traction) but not as much as would be present without the anti-squat of the drive.


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## yogiprophet (Jan 9, 2006)

Another fan of the rearward axle path. Don't think we will ever be able to make a cross country racer out of it, but sure would make a fun bike to ride. Patineto, that Lahar is a sweet looking bike. Where is that guy located? You have some great drawings. 
As far as project...I am no frame builder. Just thought I would get more intelligent feedback on this forum than some of the others. What do you think?


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## patineto (Oct 28, 2005)

yogiprophet said:


> Another fan of the rearward axle path. Don't think we will ever be able to make a cross country racer out of it, but sure would make a fun bike to ride.


Well...
If I can not ride the new tandem cross country, I just keep my Rigid IBIS that work really well.


> Patineto, that Lahar is a sweet looking bike. Where is that guy located?


I don't know I think Australia, he is also a member on "ride monkey" and maybe even here, the dude is clever as hell and very well educated, to the point I want one of his bikes even if i find them extremely ugly (question of taste here) but also extremely clever and logical in every sense.

Here are some pictures of *lahar's*
I collect over the years.

here are some other *Interesting G-boxx machines* that may help you expand your Horizons



> You have some great drawings.


Oh senor I can not type to save my life, but I'm being drawing since i can remenber do to my extreme dyslexia.


> As far as project...I am no frame builder. Just thought *I would get more intelligent feedback on this forum than some of the others*. What do you think?


Oh I think this is the most educated and evolve forum in the whole MTBr family.

Most of the members here are very open minded, but they also have a lot of "being there, done that" experience..

ps: you statement about the shock resisting loads is Wrong, very Wrong, no shock can do that and if they did they will be so overbuild the performance will be horrible, but yes a much shorter shaft present less leverage than a much longer one found on a convensional type shock


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## crank1979 (Feb 3, 2006)

patineto said:


> I don't know I think Australia, he is also a member on "ride monkey" and maybe even here, the dude is clever as hell and very well educated, to the point I want one of his bikes even if i find them extremely ugly (question of taste here) but also extremely clever and logical in every sense.
> 
> Here are some pictures of *lahar's*
> I collect over the years.


Lahar is from New Zealand.

Lahar Bikes


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## patineto (Oct 28, 2005)

[email protected] said:


> Lahar is from New Zealand.
> 
> Lahar Bikes


Ups,,,

Sorry I know that is a Horrible mistake to make.

thanks for the link.


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## dr.welby (Jan 6, 2004)

yogiprophet said:


> The front fork has a rearward path and it goes back to equalibrium after hitting a bump.


Yes, and in moving back forwards it has to be sped up.

Say the bike is moving at some speed. You hit a bump and let's just say your suspension moves backwards at some other speed. If the bike is moving forwards and the wheel backwards relative to the rest of the bike, then the wheel is moving slower than the rest of the bike. When the suspension rebounds, the wheel has to catch back up with the frame. Therefore the wheel must then be going faster than the rest of the bike until it has rebounded back to its sagged position. You pay in kinetic energy, just later in the rebound phase instead of the compression phase.


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## yogiprophet (Jan 9, 2006)

dr.welby said:


> Yes, and in moving back forwards it has to be sped up.
> 
> Say the bike is moving at some speed. You hit a bump and let's just say your suspension moves backwards at some other speed. If the bike is moving forwards and the wheel backwards relative to the rest of the bike, then the wheel is moving slower than the rest of the bike. When the suspension rebounds, the wheel has to catch back up with the frame. Therefore the wheel must then be going faster than the rest of the bike until it has rebounded back to its sagged position. You pay in kinetic energy, just later in the rebound phase instead of the compression phase.


Right...Momentum is initially gained then lost by the suspension compressing then extending.
But what I am saying is that less momentum is lost overall because the suspension has more time to compress being that it takes more time to go over an obstacle. Therefore the rider does not have to change directions as much (in the vertical) which takes much more energy than we are talking about with the wheel going back and forth. And rider fatigue would be less because the impulse would be lengthened and the forces reduced


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## yogiprophet (Jan 9, 2006)

Ugly...mabey when you judge by the cover. I look at is what is underneath. 

Thanks for the links.

Since the pull-shock is getting bad reviews I borrowed an idea from Lahar. Looks a little like my Prophet. The swingarm pivot/drive shaft and lower link pivot are held by 2 plates attached from the BB to the first horizontal tube (the lower section of the seat tube) and the shock and link go between the plates.
During full compression at both ends the wheelbase is only reduced by 6mm. No telling how this kind of bike would wheelie.
The shock leverage ratio is almost perfectly linear.


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## pvd (Jan 4, 2006)

yogiprophet said:


> Since the pull-shock is getting bad reviews...


Nobody has said anything about the use of a pull shock as being a pro or con. It's every other facet of your design that is utter garbage. Adding a linkage to the system does nothing to correct any of the problems.


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## MMcG (Jul 7, 2003)

pvd said:


> Nobody has said anything about the use of a pull shock as being a pro or con. It's every other facet of your design that is utter garbage. Adding a linkage to the system does nothing to correct any of the problems.


I'm sure this guy just loves you calling his idea "utter garbage." Maybe try being a little bit more constructive in your criticism rather than insuting the original poster over an over again.

Give it a try - you just might like it.


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## yogiprophet (Jan 9, 2006)

MMcG said:


> I'm sure this guy just loves you calling his idea "utter garbage." Maybe try being a little bit more constructive in your criticism rather than insuting the original poster over an over again.
> 
> Give it a try - you just might like it.


I'm actually getting a kick out it...it is rather funny 

This is actually a successful design in the downhill scene. It would be cool to see it play out in the "all-mountain" realm.

I question how it would pedal, how it would corner in tight situations and climb. Downhill it would rock! No pedal feedback - wonder what that would be like on a fully suspended bicycle.
Would take some time to treak I am sure, but would most likely be worth it.

The dynamics of full suspension mountain bikes is very complicated and very few have a full understanding. I have noticed that even the manufacturers of FS bikes do not understand and their designs are mostly driven by marketing hype.


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## dr.welby (Jan 6, 2004)

yogiprophet said:


> But what I am saying is that less momentum is lost overall because the suspension has more time to compress being that it takes more time to go over an obstacle.


That doesn't happen in the physics involved. Any kinetic energy saved by slowing the rear wheel is then lost speeding it back up. There's no asymmetry to it.

And if did work that way, I'm sure the motocross and Baja people, who have R&D budgets that are probably 2 orders of magnitude bigger that MTBs, would have figured that out.


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## pvd (Jan 4, 2006)

yogiprophet said:


> This is actually a successful design in the downhill scene.


Where? Not in racing. The last real effort with this was the Cannondale World Cup bikes about 10 years ago.



yogiprophet said:


> No pedal feedback...


Yes. Pedal feedback. Just not due to swingarm growth.


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## Thylacine (Feb 29, 2004)

patineto said:


> Ups,,,
> 
> Sorry I know that is a Horrible mistake to make.
> 
> thanks for the link.


I am deeply offended by your overtones of racism! How dare you call Lahar, Australian!


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## Thylacine (Feb 29, 2004)

pvd said:


> Where? Not in racing. The last real effort with this was the Cannondale World Cup bikes about 10 years ago.


Rubbish. Nicolas Vouilioz OWNED the WC for years on a similar design, and the Balfa BB7 has been in constant production for over 10 years with continued success.

However, you're right about the fact that the chain loading has absolutely no effect on the system, but having built one, I now know that having a completely 'active' bike is not super appropriate for a bicycle.

Lay off the angry pills Pete!


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## D.F.L. (Jan 3, 2004)

High pivot designs have real advantages on square-edged hits. There's less tendency for the wheel to hang up behind the obstacle. More important at speed.

What somebody, perhaps somebody who likes equations, should do is to calculate anti-squat forces for a constant CG and variable swingarm angles and acceleration rates. 

I've yet to see a successful pedal-able high pivot, jackshaft bike. Is it because the amount of wheelbase change required to provide anti-squat is so great that it results in pedal feedback due to rear wheel slow down/speed during travel?

Answer this and then criticize.


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## MMcG (Jul 7, 2003)

Thylacine said:


> Rubbish. Nicolas Vouilioz OWNED the WC for years on a similar design, and the Balfa BB7 has been in constant production for over 10 years with continued success.
> 
> However, you're right about the fact that the chain loading has absolutely no effect on the system, but having built one, I now know that having a completely 'active' bike is not super appropriate for a bicycle.
> 
> Lay off the angry pills Pete!


However the bb7 is now the Appalache Real as Balfa is no longer. Procycle pulled the plug back in mid 2004 on Balfa. 

Here's a look at the Appalache:










I used to rep for them part time here in New England. If Balfa UK is still offering some bb7s (which I don't think they are) those frames are just New Old Stock they bought from Procycle when the plug was pulled.

Long Live Balfa!


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## patineto (Oct 28, 2005)

Thylacine said:


> I am deeply offended by your overtones of racism! How dare you call Lahar, Australian!


"I don't know *I think* Australia"


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## yogiprophet (Jan 9, 2006)

Thylacine said:


> However, you're right about the fact that the chain loading has absolutely no effect on the system, but having built one, I now know that having a completely 'active' bike is not super appropriate for a bicycle.


Thanks Thylacine. 
I would like to hear more about how the bike you built feels, and the qualities that you did and didn't like. 
Was it a high pivot design like the one I posted?


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## yogiprophet (Jan 9, 2006)

D.F.L. said:


> I've yet to see a successful pedal-able high pivot, jackshaft bike. Is it because the amount of wheelbase change required to provide anti-squat is so great that it results in pedal feedback due to rear wheel slow down/speed during travel?


I was wondering what it would feel like. If you have riden one, can you tell me? I can imagine it would seem sort of wierd to ride. Like I said, wheelies and manuals would be next to impossible, but I wonder what rocky terrain would be like. I would think that technical climbing would be a blast. I never rode a Klein Mantra, but it was reported to climb like a goat. I realize that is a URT, but the concept is similar.


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## ScaryJerry (Jan 12, 2004)

Yeah! JACKSHAFT is back and ruining lives once again!!!


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## pvd (Jan 4, 2006)

Here's how a single pivot, jack shaft bike gets done right. Note that the swingarm pivot is not concentric with the jackshaft:


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## Thylacine (Feb 29, 2004)

yogiprophet said:


> I was wondering what it would feel like. If you have riden one, can you tell me? I can imagine it would seem sort of wierd to ride. Like I said, wheelies and manuals would be next to impossible, but I wonder what rocky terrain would be like.


It's just too active and on the one I did, the rearward axle path was too rearward. Felt great the faster you went, but didn't work very well when going slow. Had some brake jack but nothing too disturbing.

I wouldn't do one again, knowing now what I know about suspension design on bikes, which is still not a whole lot.

Still, it would be interesting to do another with a slightly lower pivot, a Rohloff and a modern shock, as well as a system to play around with the location of the idler.


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## MichauxYeti (Nov 10, 2005)

pvd said:


> Here's how a single pivot, jack shaft bike gets done right. Note that the swingarm pivot is not concentric with the jackshaft:


That thing would be an absolute blast if you replaced the g-box with an electric motor and replaced the crankset with pegs.


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## yogiprophet (Jan 9, 2006)

MichauxYeti said:


> That thing would be an absolute blast if you replaced the g-box with an electric motor and replaced the crankset with pegs.


It's a moped with an IC engine. See the gas tank...it even says "gas" on the side. There's even a place for a bottle mount. Very Cool


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## yogiprophet (Jan 9, 2006)

Thylacine said:


> It's just too active and on the one I did, the rearward axle path was too rearward. Felt great the faster you went, but didn't work very well when going slow. Had some brake jack but nothing too disturbing.
> 
> I wouldn't do one again, knowing now what I know about suspension design on bikes, which is still not a whole lot.
> 
> Still, it would be interesting to do another with a slightly lower pivot, a Rohloff and a modern shock, as well as a system to play around with the location of the idler.


Yes, that would be very interesting. And modern shocks are most of what make todays suspension bikes so much better.
Would like to see a picture of that bike.


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## MichauxYeti (Nov 10, 2005)

yogiprophet said:


> It's a moped with an IC engine. See the gas tank...it even says "gas" on the side. There's even a place for a bottle mount. Very Cool


Not quite. The bike in PVD's picture is Honda's RN01G downhill bike that Greg Minaar piloted the past few years.


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## DWF (Jan 12, 2004)

D.F.L. said:


> I've yet to see a successful pedal-able high pivot, jackshaft bike. Is it because the amount of wheelbase change required to provide anti-squat is so great that it results in pedal feedback due to rear wheel slow down/speed during travel?
> 
> Answer this and then criticize.


None of that applies to my Racelink. It pedals as well as or better than any other 9" travel bike I've ridden and actually pedals as well as my four-bar V-Tach when it's set up just as plush (and the ProPedal is turned off). It is a little porky.


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## yogiprophet (Jan 9, 2006)

DWF said:


> None of that applies to my Racelink. It pedals as well as or better than any other 9" travel bike I've ridden and actually pedals as well as my four-bar V-Tach when it's set up just as plush (and the ProPedal is turned off). It is a little porky.


DWF, that is one sweet looking bike you have there. Can you make a lighter 5-6" travel version for me? 
What do you think a trail bike with a similar rear end would ride like?


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## DWF (Jan 12, 2004)

yogiprophet said:


> DWF, that is one sweet looking bike you have there. Can you make a lighter 5-6" travel version for me?
> What do you think a trail bike with a similar rear end would ride like?


Yogi - I didn't build it, Chris Bourdeaux, aka "Doc" did when he was at Brooklyn Machine Works.  BMW has a new & similar 6" bike  but I know nothing about it or its ride characteristics.


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## Evil4bc (Apr 13, 2004)

pvd said:


> Nobody has said anything about the use of a pull shock as being a pro or con. It's every other facet of your design that is utter garbage. Adding a linkage to the system does nothing to correct any of the problems.


What about avability of Pull shoks ? no one make them any longer and the reason behind them not being made they sucked BIG TIME!!
the quaility of the pull shoks on the market back in the day ( 97-01) were garbage and coulnt handle the higher compression ratio's of current crop of DH bikes back then , now a days compression ratio's have been brought down allot from the 4:1 range back down to a nice 2:1 but this still doesnt mean we need to see a rebirth of a pull shok , also PVD has a very good point your design isn going to be any better by adding a linkage .
Once you have spent the time to evalute the suspension feel your looking for then make a design that can give you this intended feel don't start with a design then try to adapt it to what the masses tel you what it should feel like !


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## chequamagon (Oct 4, 2006)

pvd said:


> every other facet of your design that is utter garbage.


You are such a nice guy! It is no wonder everyone respects you so much here.


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## playpunk (Apr 1, 2005)

chequamagon said:


> You are such a nice guy! It is no wonder everyone respects you so much here.


this coming from sally sweetness herself.


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## pvd (Jan 4, 2006)

chequamagon said:


> ...


I will only respond to people who bring something to this discussion. Ante up or get lost.


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## pvd (Jan 4, 2006)

Evil4bc said:


> What about avability of pull shocks?


I wouldn't blame that on the pull shock itself. Nothing about it's design should make it inferior in any way. I think that since so few designs used a pull shock, not much engineering time or attention went into them. Kind of like a cart and horse issue.

Bucky liked tension. He did some nice things with it. Tension is a nice, efficient, light construction tool. Compression is as well. The each can be used in very creative ways.


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## Evil4bc (Apr 13, 2004)

pvd said:


> I will only respond to people who bring something to this discussion. Ante up or get lost.


I might not agree 100% with everything PVD says , but this comment is signature worthy !!
:thumbsup:


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## chequamagon (Oct 4, 2006)

yogiprophet said:


> Ugly...mabey when you judge by the cover. I look at is what is underneath.
> 
> Thanks for the links.
> 
> ...


um dood, GT made that bike in 1994 and called it the RTS. been there, done that.


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## yogiprophet (Jan 9, 2006)

chequamagon said:


> um dood, GT made that bike in 1994 and called it the RTS. been there, done that.


Wooo, the resemblance is scary. Except for one important difference. The GT has way too much anti-squat. WAAAY TOO MUCH!!!


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## chequamagon (Oct 4, 2006)

yogiprophet said:


> Wooo, the resemblance is scary. Except for one important difference. The GT has way too much anti-squat. WAAAY TOO MUCH!!!


Uh yeah, which you plan to battle with your concentric drive. Which will deliver too little. So........

This whole thread is about putting lipstick on a pig. If you want a single pivot, mount it forward of the BB around middle chainring height, ala SC Heckler. Otherwise you are in for some design issues no matter how you slice it.


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## Kyle88 (May 30, 2007)

pvd said:


> Nobody has said anything about the use of a pull shock as being a pro or con. It's every other facet of your design that is utter garbage. Adding a linkage to the system does nothing to correct any of the problems.


Is it just me or is it very difficult to take PVD seriously when he's so negative? :madman:

Out of curiosity what's your favorite design/frame and why do you hate it?


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