[ÆX]

Like pedal feedback and ultra-harsh feeling while trying to pedal through rough terrain caused by chain extention. Of course with a roller you can get around this, but the magazines and other people aren't lying to you, it's simply that most "high pivot" bikes make no provision for the extending chainline.

 

[Jm_]

BCD

Please tell me what high pivot bike doesn't suffer from pedal feedback. Just because you like to feel the suspension stop working when your pedaling force causes the rear end to stiffen doesn't mean it's working well.

 

[ÆX]

Please tell me what high pivot bike doesn't suffer from pedal feedback.

b/c the chain with the load on it is raised near or concentric to
the high pivot. by doing this the chain follows a-b-c not lengthening
so you do not feel any chain growth even when full travel is used.

 

[ÆX]

Of course with a roller you can get around this, but the magazines and other people aren't lying to you, it's simply that most "high pivot" bikes make no provision for the extending chainline.

and thats ashame, good for the people who have figured it out though! its flat out the best way to make a bike ride smoother,
might not pedal as well as a dw/vpp/4bar, but a fine compromise
IMO.

 

[metzy]

thanks BCD,
You guys are thinking like guys with standard drive chains. High pivot + chain in the right place = huge advantage.

Have attached some basic moto theory, read and understand. from this you can figure out where to stick a pivot and a chainline to get a bike that does NOT bob. Bump absorption is another story, needless a high pivot if a very good thing.

And yes, Moto theory does apply to Bicycles. Don't give me that " a moto has an engine" bull****.

 

[Lotus SE]

thanks BCD,
You guys are thinking like guys with standard drive chains. High pivot + chain in the right place = huge advantage.

Have attached some basic moto theory, read and understand. from this you can figure out where to stick a pivot and a chainline to get a bike that does NOT bob. Bump absorption is another story, needless a high pivot if a very good thing.

And yes, Moto theory does apply to Bicycles. Don't give me that " a moto has an engine" bull****.

The example you show "with a high pivot point" also has the chain, sprocket, and swing arm (including pivot point) all inline. Any tension on the chain is reacted by the rigid swing arm, and shouldn't cause a moment about the pivot point.

On a bike there is no way to have a "high pivot point" with chain, sprocket, and pivot inline... Your crank would be just slightly below your seat...

The power delivery of a 2 stroke motorcycle engine is very different from that of a pedaling human... The motorcycle engine provides 1 pulse per cylinder per stroke x the # of rpm (usually in the 1000's), and have very little reciprocating mass). The high frequency of power pulses provides a nearly seamless tension on the chain.

A human provides 2 pulses per rpm (measured in the dozens). The low natural frequency combined with the relatively soft suspension and tire springrate, combined with the large amount of body mass traveling up and down, will result in a noticeable suspension bob. You can damp it out, but doing so will compromise suspension performance in other ways.

Two totally different systems.

 

[metzy]

Please look at the info I posted. NOTE: it is possible to get a neutral pedalling system even if the chain is not inline with the pivot!. Chain force is not the only thing going on here, we have weight transfer (compression force) & what the literature some time calls chain pull effect (extension force)(look at the info), these two things are proportional and can be balanced whether or not the chain is inline with the pivot. As soon as you understand this you will realise what a bunch of ass gimicks like Istant centre tracking etc is.

Which brings me to the next point. A moto and a suspension bicycle obey the same laws of physics and can be analysed using the same tools. It doesn't matter what frequency, how large the forces are..... a bike will squat if designed to squat, be nuetral if designed to be nuetral, jack if designed to jack. Similarly front linkages forks can be designed to behave in many fashions on braking.

Please don't give me that " motos are different than bicycles ****", I have had this discussion with some of the most respected motorcycle chassis designers in the world, Moto = bicycle

 

[Jm_]

b/c the chain with the load on it is raised near or concentric to
the high pivot. by doing this the chain follows a-b-c not lengthening
so you do not feel any chain growth even when full travel is used.

Evidently you didn't read my first post.

 

[BIGHITR]

Hard Tail DH bike...

 

[Bldr_DH]

Wow, necropost much?

Still awesome though.

 

[CBJ]

 

[mattmatt86]

Looks awesome, when came I order one?

 

[sadasskoala]

thats an awsome bike dude

 

[iridebikes]

wow... 2 year old thread brough back up to the top. Crazy!