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Rearward travel affecting geometry?

norbar

KESSLER PROBLEM. Just cause
Jun 7, 2007
11,346
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Warsaw :/
I'm very possitive on rearward travel suspension advantages on rough stuff but recently someone pointed one think that I can't get out of my mind.
How much heavy rearward travel and growing of the bike wb connected with it affects bike turning ability?
Ie. If the bike has a really rearward travel (like Appalache or Canfield) will it harm it's turning ability? Will it be noticable?
 

mandown

Poopdeck Repost
Jun 1, 2004
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it depends. if you just look only at wheelbase, then yes the turning ability will be harmed as the rear suspension compresses and the wheelbase grows. however, in most cases i would think the fork compresses in a turn at a rate comparable to the rear suspension compression, keeping the wheelbase close to constant through the turn. of course there are some variables going on: how is your suspension set up? what type of corner is it (uphill/downhill/level/switchback)? how well do you ride corners?

i owned a balfa bb7 for a few seasons and it was a great bike. i never had a problem with the wheelbase growth busting my ability to corner. that said, i also wasn't very good in corners when i owned it. my last two bikes have been lower single pivots (bottlerocket ant UFO ST) the UFO is comparable to the BB7 in total travel, and i do notice it corners better. some of that is due to my bike setup being different (tire choice, fork, lower BB height). however, i did notice on my last whistler trip the UFO has a much more noticable acceleration coming out of corners than the BB7 ever did. some of that is due to a few years of experience helping me corner better, but i think a fair amount of it is due to geometry.
 

buildyourown

Turbo Monkey
Feb 9, 2004
4,832
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South Seattle
I think the chainstay length has more to do with it than the wheelbase.
This is one reason I think that low single pivots corner better. As you push into the turn through you pedals, the chainstays effectively get shorter and pop you out of th turn.
I think this is riding style decision. Bikes with very low pivots do seem to suffer in the really fast rough stuff, but if your style is to jump and pop obstacles, rather than plow, they work well.
 

norbar

KESSLER PROBLEM. Just cause
Jun 7, 2007
11,346
1,587
Warsaw :/
I think the chainstay length has more to do with it than the wheelbase.
This is one reason I think that low single pivots corner better. As you push into the turn through you pedals, the chainstays effectively get shorter and pop you out of th turn.
I think this is riding style decision. Bikes with very low pivots do seem to suffer in the really fast rough stuff, but if your style is to jump and pop obstacles, rather than plow, they work well.
I know it's also chain stay but in very tight corner wb also counts and that's what I want to change in my current bike (48'' static + 9'' rearward travel).
I like the cornering on my xc/am bike (ellsworth joker xc) and it is a low sp bike but I have never had any serious time on a big low sp rig so I'm not sure how much worse it is on rough stuff (Ie. will it be unconfortable for me after riding a 4bar and virtual pivot lapierre for all my dh time).
I want to pop stuff and like the idea of shortening the bike and CS but not sure will it really hurt me on the rough stuff.
Any1 had experiance going from virtual to low sp's?

Also what are low sp frames with nice geo (prefferably lower bb) other than commencal and turner?
 

Jm_

sled dog's bollocks
Jan 14, 2002
18,855
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AK
I think the chainstay length has more to do with it than the wheelbase.
This is one reason I think that low single pivots corner better. As you push into the turn through you pedals, the chainstays effectively get shorter and pop you out of th turn.
I think this is riding style decision. Bikes with very low pivots do seem to suffer in the really fast rough stuff, but if your style is to jump and pop obstacles, rather than plow, they work well.
And your center of gravity stays the same relative to the position of the wheels. When they both move "backwards" your CG will move forward. I don't know whether this is necessarily good or bad, but I seem to think that on such bikes you can stay more "neutral".
 

mandown

Poopdeck Repost
Jun 1, 2004
20,134
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Also what are low sp frames with nice geo (prefferably lower bb) other than commencal and turner?
Nicolai UFO ST (size large geo)
WB = 45.8
TT = 23.6
HA = 66*
BB = wicked low (the website geo chart doesn't show it in absolute terms, but in terms of drop from BB to rear axle of 0.8" or 20mm, compared to the Commencal with a 25mm drop.) i smack pedals on stuff if i'm not careful. i measured it at one point and it was wicked low. i'm guessing a 26" wheel divided in half is 13" + the BB drop of 0.8" would put it at 13.8" which sounds close to what i recal the measurement being. this would imply the commencal is a 14" BB.

Turner site says 14.4 bb
Ventana El Cuervo claims 14.4bb
Orange 224 claims 14.2 bb
 

norbar

KESSLER PROBLEM. Just cause
Jun 7, 2007
11,346
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Warsaw :/
Actualy you need to think about the tire height also. From what I remember supreme dh was actualy about 14.5''.
Orange 224 is wicked long and is it really a low sp???
Nicolai is nice as you can customize your geo(I'd just get what I want) but it's damn heavy and I don't want to add 1kg to my bike.
 

mandown

Poopdeck Repost
Jun 1, 2004
20,134
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Transylvania 90210
yeah, i know tires are in there too, i was just throwing out a rough estimate. fork height also changes things too.

also agree, the nicolai aint light. the problem with the UFO is that it is almost too low. the only "adjustment" options on the frame are to make the bb lower, which would be damn silly compared to where it is now.
 

norbar

KESSLER PROBLEM. Just cause
Jun 7, 2007
11,346
1,587
Warsaw :/
yeah, i know tires are in there too, i was just throwing out a rough estimate. fork height also changes things too.

also agree, the nicolai aint light. the problem with the UFO is that it is almost too low. the only "adjustment" options on the frame are to make the bb lower, which would be damn silly compared to where it is now.
It's actually probably a bit over 14'' so dropping it is not such a bad idea.
 

no skid marks

Monkey
Jan 15, 2006
2,511
29
ACT Australia
When talking BB height it's very important to consider travel and therefore sag, or rideheight I guess would be an easier way of putting it.
High pivots give you a longer wheel base when you need it.
I know low pivots feel great cornering, as you slam into the corner, the wheelbase shortens and the bike feels quicker /more responsive, but I'm not sure if it actually is quicker, or if it's just in your head. "In your head is very important also though.
I'm about to try a slightly lower pivot bike(still high SP)than my BB7, I'll hopefully be able to give some more feedback soon.
My new frame will have a -17"chainstay though, so it'll feel a lot faster due to this.
If you ride rough tracks(like DH should be)then stick with the high SP, if you ride smooth tracks like big 4X tracks, then possibly go with something lower.
Please give some feedback if you do go lower.
 

zedro

Turbo Monkey
Sep 14, 2001
4,144
1
at the end of the longest line
i think you definitely need to change your riding style. My bike has maybe as much rearward travel as the BB7, but cornering was not as affected as i had feared as long as i kept a bit more weight forward. So basically if i dive into a turn, my chainstay length gets shorter as the rear wheel tucks in as i put more weight the front. Leaning back from the corner pretty much guaranteed a bush-wacking expedition.....

edit: woops, no skid beat me out
 

no skid marks

Monkey
Jan 15, 2006
2,511
29
ACT Australia
Is it true the Cove Shocker has a rearward axle path? or just marketing BS?
It starts as rearward then goes vertical(if my memory serves me correctly), so it's generally pointless. The rearward bump absorbtion is used up on sag. I'd say it's so the chain pulls it into it's sag point(another pointless idea).I'm generalising a bit here though, the Coves do ride okay, probably due to vertical axle path, geo, and low COG.
 

dirtdigger

Monkey
Mar 18, 2007
126
0
N.zud
Due to the fact that there’s not a lot of rearward travel/ high pivot bikes out there very few people are qualified to say what’s different or better.

FWIW I ride a high pivot bike with a idler and it’d be a cold day in f#$king hell before I would go back to anything else! But hey that’s just me.

Nuff said.
 

norbar

KESSLER PROBLEM. Just cause
Jun 7, 2007
11,346
1,587
Warsaw :/
i think you definitely need to change your riding style. My bike has maybe as much rearward travel as the BB7, but cornering was not as affected as i had feared as long as i kept a bit more weight forward. So basically if i dive into a turn, my chainstay length gets shorter as the rear wheel tucks in as i put more weight the front. Leaning back from the corner pretty much guaranteed a bush-wacking expedition.....

edit: woops, no skid beat me out
Actualy I have no problems with my turns and I ride pretty forward(my bike is just too long at static wb and feels long in tighter turns). I'm just not sure what are the advantages of both ideas and I'm on the market for a new frame (plus I'm very undecisive :P ).
 

Sandwich

Pig my fish!
Staff member
May 23, 2002
21,031
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borcester rhymes
I've found that I can get decent pop out of tight berms by throwing my body weight into the center of the turn, in other words packing the suspension down until the turn lets out and can spring me forward. I don't have a low pivot bike to compare to, however.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,358
0
Malaysia
i bit off topic, but i am getting confused with the terminology used here.

what i am used to is:
turner dhr, grandmal, blindeside --- low pivot bikes
commencal, orange 22x series, joker --- high pivot bikes
bb7, dh-1, lahar, bcd --- extremely high pivot bikes.

imo, i think the word high pivot comes in once there is significant amount of rearward axle path. what do you guys think?
 

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
Ah dhkid the commencal etc would class as a mid-pivot, they aren't much higher than a turner dhr.

Low/mid/high would sum it up pretty well for the bikes you gave.
 

P.T.W

Monkey
May 6, 2007
599
0
christchurch nz
Ah dhkid the commencal etc would class as a mid-pivot, they aren't much higher than a turner dhr.

Low/mid/high would sum it up pretty well for the bikes you gave.
Yeah IMO
Low-pivot= below the top of the chainring
Mid-pivot= just either side of the top of the chainlring
High-pivot = well above the top of the chainring
 

zedro

Turbo Monkey
Sep 14, 2001
4,144
1
at the end of the longest line
Actualy I have no problems with my turns and I ride pretty forward(my bike is just too long at static wb and feels long in tighter turns). I'm just not sure what are the advantages of both ideas and I'm on the market for a new frame (plus I'm very undecisive :P ).
woops, didn't mean "You" as in you personally, just in general.

just get something badass, it's really that simple....
 

Polhill

Chimp
Feb 8, 2008
10
0
Rearward travel is really only a benefit in the initial part of the bikes travel. It's all about functioning geometry not this static sag or just rolling the bike around. When you ride your bike it finds it's equilibrium. It' slike being neutrally buoyant.The geometry present at that time is what determines useful travel and geometry.
What's pointless is constantly rearward travel. The idea is to allow the wheel to move out of the way of the "bump"or obstruction as fast as possible. This has little to do with actual speed of the bike as much as it has to do with the speed that the swing arm can move the wheel up and over the "bump". You don't want the wheel to snag or hang up on the terrain because this will cause a hesitating feel to the bike and likely destroy rear wheels. Bikes that have extended "vertical" travel have a weird feel in the corners and tend to ramp up very quickly. Bikes like the Sunday and the Glory work well because at a certain point the IC makes the swing arm effectively shorter which drastically changes the arc the wheel is moving on so at high load and high velocity the wheel will move out of the way quicker than at the start of the stroke. Rearward for low amplitude vertical for midstroke stability and slightly forward to allow the wheel to move out of the way of the BIG stuff FAST. If you look at the Orange pivot location you'll see that after sag the swingarm still moves slightly rearward to end up moving slightly forward at the end. This is the similar for the Shocker as well as the Sunday and Giant bikes. As your speed increases so does your weight, effectively, so as you load your bike more the less you need the rearward travel because you'll want that wheel to spend as little time on that "bump" as possible.
 

zedro

Turbo Monkey
Sep 14, 2001
4,144
1
at the end of the longest line
...
What's pointless is constantly rearward travel. ...
as far as i know, there aren't any bikes like that. Even the BB7 (which may have the highest pivot) still reaches vertical, same with rearward path linkage bikes like the Formula 1. Maybe you could achieve it with a rail design like the Yeti, but the limitations of linkage geometry otherwise makes the attempt pretty impractical anyways; rotating multi-bar linkages always give a 'fairly' circular path.

FTW gave me a chance to try his prototype floating axle path 5-bar, unfortunately i went underground and never got the opportunity to try it :(
 
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Nixxk

Chimp
Jun 11, 2006
21
2
Well for what its worth

My BB7 i had to ride with more weight up front.
did not feel fast in corners.

My Glory DH have to ride with more weight center and back.
Feels like its turning lot faster.

But the Glory seems to slow down more in the "rock gardens" compared
to the BB7 but that could be me not setting the DHX properly.
 

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
I think that's worth plenty, backed up opinions on both bikes. Lines up with my experiences, the BB7 is good in the rough and doesn't get hung up as much but feels a little awkward when slammed into corners (especially tighter ones)... whereas the glory/sunday/turners etc seem to excel in the twisties.
 

flymybike

Monkey
Jan 7, 2004
260
0
Jackson Hole
Looking at chainstay lengths, all of the upper pulley wheel bikes except for the Canfield Jedi start at 17" or more, so at sag your already longer than a normal wheel path bike. That attributes alot to the overall "long" feel and slow turning. The Jedi starts at 16.25 and sags slightly shorter than most popular bikes and end close to the same chainstay length. As a comparison, a "race" ski shape and a parabolic "shaped" ski turn very differently and require a different technique to make them work properly. Same with wheel paths and the amount of rearward. I feel that 90% of the time I ride the rearward is a huge benefit and I wouldn't trade that for the few times when it "could" be a dissadvantage (like a skate park or dirt jumps). I have a different bike for that!
 

dirtdigger

Monkey
Mar 18, 2007
126
0
N.zud
If some one wanted to buy a high pivot/rearward travel type bike/frame right now what could they get??

apart from a jedi and BMW.
 

dhkid

Turbo Monkey
Mar 10, 2005
3,358
0
Malaysia
flymybike, i think the bcd bike has really short chain stays too, under 17.

i think riding style plays an important part on whether you will get along with a high pivot bike. the thing that annoys me is that you cant pump the terrain as well as a lower pivot bike. but then again it plows so well, you dont really need to work the terrain.
 

dirtdigger

Monkey
Mar 18, 2007
126
0
N.zud
flymybike, i think the bcd bike has really short chain stays too, under 17.

i think riding style plays an important part on whether you will get along with a high pivot bike. the thing that annoys me is that you cant pump the terrain as well as a lower pivot bike. but then again it plows so well, you dont really need to work the terrain.
Are you sure about high pivots not pumping as well as a lower pivot? what bike was that on?

My thinking is that when the rear wheel moves rearward on the down side of bumps when you compress the suspension it would push the bike forward.
 

P.T.W

Monkey
May 6, 2007
599
0
christchurch nz
Are you sure about high pivots not pumping as well as a lower pivot? what bike was that on?

My thinking is that when the rear wheel moves rearward on the down side of bumps when you compress the suspension it would push the bike forward.
That would only push the bike forward if it was a high pivot with a "conventional" drivetrain (ie no idler/gbox etc etc) as the chain pull under compression drives the bike forward.
With a idler/gbox set up to minimise chain pull(like most of the bikes mentiond in this thread) lengthening stays with no induced chain pull aint going to push nothing forward
 
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no skid marks

Monkey
Jan 15, 2006
2,511
29
ACT Australia
That would only push the bike forward if it was a high pivot with a "conventional" drivetrain (ie no idler/gbox etc etc) as the chain pull under compression drives the bike forward.
With a idler/gbox set up to minimise chain pull(like most of the bikes mentiond in this thread) lengthening stays with no induces chain pull aint going to push nothing forward
Yeah they are, they're going to push the riders center of gravity forward on compression(this is the slightly unsettling feeling,as the rear is unweighted), then the bike forward on rebound as aprox 2/3rds of the package is rider weight. This may or may not be what doesn't feel as fast as a low pivot, but I'm still not sure what actually is faster as opposed to what feels faster. A lengthening chainstay when cornering is not as confidence inspiring as a shortening one, this is true, whether the subconscious overides it with body weight, or if it is faster/slower I'm not sure. I don't think cornering confidence on such a minute difference is worth as much as rock garden, rough corner,or big jump/drop confidence, but you be the judge, ride both, but give your brain the chance to adapt and the clock the chance to judge.
I've found the rear without a floater is more ragged, but easier to tame(or so it feels)by controlling the squat/traction with the brake.
 
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