URT sucks?

[Dave Stocker]

Puts on flame retardant suit.

So after all of the URT bashing in the Giant Warp thread, I was wondering what everyone's beef is
with URT anyway. It is a design with advantages and disadvantages, just like any other suspension
design. It seemed to be a fad a few years ago to build URT designs (Trek Y-bikes, Klein Mantra, etc)
and that it has fallen out of favor because it did not deliver on it's hype. At one time URT was
considered a great thing ( http://www.cycletech.com/TechTips/body.htm and look at the bottom). Now
is seems to be hated. In a recent Velo News article, the author seems to sneer at somebody he meets
on the trail because that rider liked his URT bike.
http://www.velonews.com/tech/report/articles/4082.0.html So the mags say it is fashionable to hate
URT, but a few years ago they were touting it. Does it really suck that bad?

From googling a bit, I can say that the generally accepted behavior traits of the URT are:
- It is immune to bob on out of saddle sprints. <good>
- Supposedly they bob (especially low pivot designs) <bad>
- It has no pedal kickback. <good>
- Prone to brake jack <bad>
- BB-seat distance varies <bad>
- Only active if rider remains seated (rider stands on swing arm when out of saddle) <bad?>

I have a mid-90's Katraga Proto Winner in my garage that I have logged a lot of miles on. FYI, a
little background- Katarga is an Austrian bike maker that I would not call boutique. They are a
small maker of low to mid end bikes, inhabiting the same ecological niche as e.g. GT. The Proto
Winner was a URT design that they sold in the mid to late 90's. It is not a high pivot design like
the Mantra. The BB sits about 2" directly behind the pivot. If you are interested in what it looks
like, I could photograph it, but I do not have a web page at the moment to post it to.

From my experience on this bike I can report:
- It does bob a little bit if you pedal very badly, but bob is easy to completely eliminate with a
seated spin (easier than with 4-bar). I do not know where the low pivot URT bikes developed the
reputation for bobbing. It really does behave like a hardtail on out of saddle sprints. On steep
climbs this is a good thing or a bad thing, depending on your perspective. I tend to pull hard on
the upstroke and climb better on a more "conventional" FS design than on a URT.
- Never experienced pedal kickback. Hell, I could run this bike as an SS.
- Brake Jack. I hate that term. This bike has a low pivot and this is not really an issue. I have
heard that it can be quite severe on a high pivot bike.
- BB-Seat distance only varies by about a half an inch at full travel on this bike. No biggie.
- The not active part I can attest to. I recently bought a four bar bike and now the old URT bikes
seems quite harsh and inactive. It is still taking the edge off of hits. In this respect, it
behaves a bit like a heavy (13kg) Giant NRS.

There is no suspension design that is the Holy Grail. Path Analysis makes interesting reading if you
have the proper background: http://www.mtbcomprador.com/pa/english/ IMHO- URT does quite well in a
couple of applications:
1) The lightest FS frames are single pivot. URT is basically single pivot with the BB on the rear
triangle. It follows that a URT frame could make it into the 4lb range. One good application
would be XC marathon bike where big travel was not an issue and the suspension is mostly there to
take the edge off and delay the onset of fatigue. The NRS works this way. My old low pivot URT
bike is too heavy to be considered for racing, but it is great on epic rides. Too bad URT is
unfashionable. It could in principle be used for a great XC marathon bike.
2) Touring bikes and Walgooses. Wallgoose buyers want the FS look and tourers want to take the edge
off, but both are ridden by people who probably have never (and never will) practiced a clean
spin. I do not buy the "URT bobs like crazy" line. The FSR bobs like crazy if I do not spin
smoothly. The URT bike is very forgiving.

In short, it URT has shortcomings, but the vilification of URT has more to do with fashion than
anything else. Remenber, the macstrut is making a comback.

Runs for cover.

-Dave

 

[P E T E F A G E]

On Wed, 25 Jun 2003 00:34:30 +0200, "Dave Stocker" <[email protected]> wrote:

|From googling a bit, I can say that the generally accepted behavior traits |of the URT are:
|- It is immune to bob on out of saddle sprints. <good>

********.

|- Supposedly they bob (especially low pivot designs) <bad>

All FS bikes bob to some extent.

|- It has no pedal kickback. <good>
|- Prone to brake jack <bad>
|- BB-seat distance varies <bad>

Very bad.

|- Only active if rider remains seated (rider stands on swing arm when out of
|saddle) <bad?>

Not necceessarily.

<huge snip>

|In short, it URT has shortcomings, but the vilification of URT has more to |do with fashion than
anything else.

URTs have many shortcomings when compared to four bar bikes.

The "vilification" isn't always based upon fashion issues. Many times it is based upon the fact that
there are much better full suspension designs available.

 

[Dave Stocker]

"P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
news:[email protected]...
> On Wed, 25 Jun 2003 00:34:30 +0200, "Dave Stocker" <[email protected]> wrote:
>
> |From googling a bit, I can say that the generally accepted behavior
traits
> |of the URT are:
> |- It is immune to bob on out of saddle sprints. <good>
>
> ********.

Perhaps "immune" is a strong word, but standing does act as a lockout.

>
> |- Supposedly they bob (especially low pivot designs) <bad>
>
> All FS bikes bob to some extent.
>

Yup. What I should have said was the "URT bikes are especially prone to bob". My four bar is far
more prone to bobbing than my URT.

> |- It has no pedal kickback. <good>
> |- Prone to brake jack <bad>
> |- BB-seat distance varies <bad>
>
> Very bad.
>
> |- Only active if rider remains seated (rider stands on swing arm when out
of
> |saddle) <bad?>
>
> Not necceessarily.
>

Actually true. I have never ridden a Mantra, but from what I have heard about its behavior, this is
a prominent feature. Some like it, some hate
it.

> <huge snip>
>
> |In short, it URT has shortcomings, but the vilification of URT has more
to
> |do with fashion than anything else.
>
> URTs have many shortcomings when compared to four bar bikes.
>
> The "vilification" isn't always based upon fashion issues. Many times it is based upon the fact
> that there are much better full suspension designs available.

But Pete, what I am trying to say is that many of the supposed problems of URT stem from specific
implementations of it, not the principle itself. Is my FSR a better trail bike than the Katarga? You
betcha. It is smoother and faster over the rough stuff and I do steep technical climbs better with
it than with the URT bike or with a hardtail.

But- if I were entering a race, I would have to think long and hard about which bike to use, even
though the Katarga weighs 5lb more. The FSR climbs and descends better, but the Katarga sprints
better and bobs less. Also smoother and more active is not necessarily better. There are people in
this NG who advocate rigid. After riding the FSR for a couple of months now I can see how it can
lull me into bad habits and I understand this rigid advocacy much more.

What I tried to say in my original post was that URT, like any other suspension type, has its pros
and cons and it has its niche. When people say URT sucks, they are usually extrapolating the
shortfalls of a particular design to the principle.

-Dave

 

[Chris Phillipo]

In article <[email protected]>, [email protected] says...
> Puts on flame retardant suit.
>
> So after all of the URT bashing in the Giant Warp thread, I was wondering what everyone's beef is
> with URT anyway. It is a design with advantages and disadvantages, just like any other suspension
> design. It seemed to be a fad a few years ago to build URT designs (Trek Y-bikes, Klein Mantra,
> etc) and that it has fallen out of favor because it did not deliver on it's hype. At one time URT
> was considered a great thing ( http://www.cycletech.com/TechTips/body.htm and look at the bottom).
> Now is seems to be hated. In a recent Velo News article, the author seems to sneer at somebody he
> meets on the trail because that rider liked his URT bike.
> http://www.velonews.com/tech/report/articles/4082.0.html So the mags say it is fashionable to hate
> URT, but a few years ago they were touting it. Does it really suck that bad?
>

The main feature and the main reason it sucks is that standing up cancels out the suspension because
you are standing on the unsprung part of the bike. Sounds for pedaling but you actually have to go
down a hill at some point. Then as you mentioned there's the while BB to seat measurement constantly
changing which is never good. Ideally you want a rear wheel that moves up and done as independently
from the rider as possible. That's why I haven't found anything to beat the FSR design yet.

--
_________________________
Chris Phillipo - Cape Breton, Nova Scotia http://www.ramsays-online.com

 

[Chris Phillipo]

In article <[email protected]>, [email protected] says...
> In article <[email protected]>, [email protected] says...
> > Puts on flame retardant suit.
> >
> > So after all of the URT bashing in the Giant Warp thread, I was wondering what everyone's beef
> > is with URT anyway. It is a design with advantages and disadvantages, just like any other
> > suspension design. It seemed to be a fad a few years ago to build URT designs (Trek Y-bikes,
> > Klein Mantra, etc) and that it has fallen out of favor because it did not deliver on it's hype.
> > At one time URT was considered a great thing ( http://www.cycletech.com/TechTips/body.htm and
> > look at the bottom). Now is seems to be hated. In a recent Velo News article, the author seems
> > to sneer at somebody he meets on the trail because that rider liked his URT bike.
> > http://www.velonews.com/tech/report/articles/4082.0.html So the mags say it is fashionable to
> > hate URT, but a few years ago they were touting it. Does it really suck that bad?
> >
>
> The main feature and the main reason it sucks is that standing up cancels out the suspension
> because you are standing on the unsprung part of the bike. Sounds for pedaling but you actually
> have to go down a hill at some point. Then as you mentioned there's the while BB to seat
> measurement constantly changing which is never good. Ideally you want a rear wheel that moves up
> and done as independently from the rider as possible. That's why I haven't found anything to beat
> the FSR design yet.
>
>

Holy crappy spell checker batman.
--
_________________________
Chris Phillipo - Cape Breton, Nova Scotia http://www.ramsays-online.com

 

[P E T E F A G E]

On Wed, 25 Jun 2003 08:37:46 +0200, "Dave Stocker" <[email protected]> wrote:

>"P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
>news:[email protected]...
>> On Wed, 25 Jun 2003 00:34:30 +0200, "Dave Stocker" <[email protected]> wrote:
>>
>> |From googling a bit, I can say that the generally accepted behavior
>traits
>> |of the URT are:
>> |- It is immune to bob on out of saddle sprints. <good>
>>
>> ********.
>
>Perhaps "immune" is a strong word, but standing does act as a lockout.

Not on all URTs.

>> |- Supposedly they bob (especially low pivot designs) <bad>
>>
>> All FS bikes bob to some extent.
>>
>
>Yup. What I should have said was the "URT bikes are especially prone to bob". My four bar is far
>more prone to bobbing than my URT.
>
>> |- It has no pedal kickback. <good>
>> |- Prone to brake jack <bad>
>> |- BB-seat distance varies <bad>
>>
>> Very bad.
>>
>> |- Only active if rider remains seated (rider stands on swing arm when out
>of
>> |saddle) <bad?>
>>
>> Not necceessarily.
>>
>
>Actually true.

Actually false. The Ibis Bow Ti is active when you are out of the saddle. Less active than when you
are seated, but active nonetheless.

I have never ridden a Mantra, but from what I have heard
>about its behavior, this is a prominent feature.

So because you've heard that this is a characteristic of one flavor of URTs, it follows that all
URTs are only active when the rider is seated?

Some like it, some hate
>it.
>
>> <huge snip>
>>
>> |In short, it URT has shortcomings, but the vilification of URT has more
>to
>> |do with fashion than anything else.
>>
>> URTs have many shortcomings when compared to four bar bikes.
>>
>> The "vilification" isn't always based upon fashion issues. Many times it is based upon the fact
>> that there are much better full suspension designs available.
>
>But Pete, what I am trying to say is that many of the supposed problems of URT stem from specific
>implementations of it, not the principle itself.

That sounds like double speak.

The "suppsed" problems associated with URTs (principle) aren't "supposed," they are very real.

<snip>

>What I tried to say in my original post was that URT, like any other suspension type, has its pros
>and cons and it has its niche. When people say URT sucks, they are usually extrapolating the
>shortfalls of a particular design to the principle.

You seem to be hung up on creating a difference between design and principle.

For example, the URT principle involves a constantly changing BB to saddle distance. This is not
specific to a particular design, but rather to all URTs..

 

[Dave Stocker]

"P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
news:[email protected]...
> >> |- Only active if rider remains seated (rider stands on swing arm when
out
> >of
> >> |saddle) <bad?>
> >>
> >> Not necceessarily.
> >>
> >
> >Actually true.
>
> Actually false. The Ibis Bow Ti is active when you are out of the saddle. Less active than when
> you are seated, but active nonetheless.
>

Holy Cow! That monstrosity is a URT? I have never seen this thing in real life, but I found this
picture. http://www.soresaddle.com/ibisbowbi.jpeg

OK, lets define URT before we go any further. If you defined it as variable BB-saddle distance, then
yes, it would be a URT. But titanium monstrosities are not comparable to pivot based bikes made with
relatively inflexible materials. From the fact that it is ti and a look at the layout, I think I get
the basic principal of how it works*. Calling this bike a URT would be like cutting the seatstay out
of a Scalpel or Unicoi (or most hardtails for that matter) and redefining them as URT bikes. I would
define unified rear triangle as a pivot based bike with the BB on the rear triangle. In this
definition of URT, when you get out of the saddle, you are standing on the rear triangle and holding
on to (in a roundabout way) the front triangle.

*It appears to be a big leaf spring. When you sit on it, you add a considerable preload and thus it
is not very active. When you stand, you are unloading that preload. It looks clever. Has anyone here
ever ridden one? Nevertheless, IMHO, it is inappropriate to label this thing URT.

-Dave

 

[MTBScottie]

"Dave Stocker" <[email protected]> wrote in message news:<[email protected]>...
> "P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
> news:[email protected]...
> > On Wed, 25 Jun 2003 00:34:30 +0200, "Dave Stocker" <[email protected]> wrote:
> >
> > |From googling a bit, I can say that the generally accepted behavior
> traits
> > |of the URT are:
> > |- It is immune to bob on out of saddle sprints. <good>
> >
> > ********.
>
> Perhaps "immune" is a strong word, but standing does act as a lockout.
>
> >
> > |- Supposedly they bob (especially low pivot designs) <bad>
> >
> > All FS bikes bob to some extent.
> >
>
> Yup. What I should have said was the "URT bikes are especially prone to bob". My four bar is far
> more prone to bobbing than my URT.
>
> > |- It has no pedal kickback. <good>
> > |- Prone to brake jack <bad>
> > |- BB-seat distance varies <bad>
> >
> > Very bad.
> >
> > |- Only active if rider remains seated (rider stands on swing arm when out
> of
> > |saddle) <bad?>
> >
> > Not necceessarily.
> >
>
> Actually true. I have never ridden a Mantra, but from what I have heard about its behavior, this
> is a prominent feature. Some like it, some hate
> it.
>
> > <huge snip>
> >
> > |In short, it URT has shortcomings, but the vilification of URT has more
> to
> > |do with fashion than anything else.
> >
> > URTs have many shortcomings when compared to four bar bikes.
> >
> > The "vilification" isn't always based upon fashion issues. Many times it is based upon the fact
> > that there are much better full suspension designs available.
>
> But Pete, what I am trying to say is that many of the supposed problems of URT stem from specific
> implementations of it, not the principle itself. Is my FSR a better trail bike than the Katarga?
> You betcha. It is smoother and faster over the rough stuff and I do steep technical climbs better
> with it than with the URT bike or with a hardtail.
>
>
>
> But- if I were entering a race, I would have to think long and hard about which bike to use, even
> though the Katarga weighs 5lb more. The FSR climbs and descends better, but the Katarga sprints
> better and bobs less. Also smoother and more active is not necessarily better. There are people in
> this NG who advocate rigid. After riding the FSR for a couple of months now I can see how it can
> lull me into bad habits and I understand this rigid advocacy much more.
>
>
>
> What I tried to say in my original post was that URT, like any other suspension type, has its pros
> and cons and it has its niche. When people say URT sucks, they are usually extrapolating the
> shortfalls of a particular design to the principle.
>
> -Dave

Thanks for the informative post Dave

 

[Dave Stocker]

"P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
news:[email protected]...

<start with some snippage>

> >But Pete, what I am trying to say is that many of the supposed problems
of
> >URT stem from specific implementations of it, not the principle itself.
>
> That sounds like double speak.

Hmmm, work is wearing off on me. ;-). Alow me translate: Just because certain URT designs blow mokey
chunks, it does not follow that all possible URT designs blow monkey chunks.

> >> |- Only active if rider remains seated (rider stands on swing arm when
out
> >of saddle) <bad?>
> >>
> >> Not necceessarily.
> >>
> >Actually true.
>
<snip bit about titanium monstrosity>

> I have never ridden a Mantra, but from what I have heard
> >about its behavior, this is a prominent feature.
>
> So because you've heard that this is a characteristic of one flavor of URTs, it follows that all
> URTs are only active when the rider is seated?
>

So because I have seen this characteristic on one flavor of URT that I have ridden extensively and
(mostly) because on all URTs, you are standing on the swingarm, it follows that all URTs are
dampened to some degree depending how far the BB is from the pivot. Actually the mantra bit results
from a misunderstanding. When you answered "Not necessarily", I had initially assumed you were
referring to the statement, so I answered "Actually True". Then it occurred to me that you were
referring to the "<bad>" part.

Standing on the swingarm does essentially causes the rear to have two spring rates where the
difference in k is proportional to the distance from BB to pivot. I myself like it when
sprinting and cutting through fast singletrack, but not when bombing downhill. Now I had heard
that some people like this feature and some do not (just like I have heard on this NG that some
people like SS). So I could see how you would answer that way. Of course I had a brain fart and
did not edit my initial reply.

After seeing the Ibex reference, I now believe that you meant to answer to the whole statement. I
misunderstood you and was not clear myself. For this I apologize.

<more snippage>

>
> You seem to be hung up on creating a difference between design and principle.
>

Yes, I am being anal. Bear with me for a moment: If we define the URT as having the BB on the rear
triangle then this is the principle. It could be a single pivot or a multi-pivot bike, but the BB
must be on the rear triangle - and yes, the BB moves around relative to the saddle, but is fixed
with respect to the rear hub. This encompasses the set of all possible ways (existing or not) this
could be done. The only things that ALL URT designs share are the BB-saddle thing and the fact that
you stand on the rear triangle. Even these two things are greatly variable due to pivot placement.

When people say "URT sucks", they are saying the "all possible ways" suck. That is what I am taking
issue with. And I bet at least one of those people who chimed in that "URT sucks" never actually
rode one. I am mot saying URT is the best day to go. I am not even saying that MY URT is better than
MY FSR (I take the FSR out 95% of the time for a reason). I am saying that my URT has some strengths
and does not have some of the weakness attributed to the "set of all possible ways". It is better
suited than my FSR for "fireroad epics" and smooth singltrack. IMHO- it has its proper niche(s), but
it had the misfortune of being a fad that fell out of fashion.

BTW- I rode a mid/late-80's Bianchi road bike with Biopace chainrings a couple of weeks ago. Biopace
is almost THE example of a "discredited technofad". I came away neither impressed, nor unimpressed.

-Dave

 

[P E T E F A G E]

On Wed, 25 Jun 2003 21:03:53 +0200, "Dave Stocker" <[email protected]> wrote:

|"P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
|news:[email protected]...
|> >> |- Only active if rider remains seated (rider stands on swing arm when
|out
|> >of
|> >> |saddle) <bad?>
|> >>
|> >> Not necceessarily.
|> >>
|> >
|> >Actually true.
|>
|> Actually false. The Ibis Bow Ti is active when you are out of the saddle. Less active than when
|> you are seated, but active nonetheless.
|>
|
|Holy Cow! That monstrosity is a URT? I have never seen this thing in real |life, but I found this
picture. http://www.soresaddle.com/ibisbowbi.jpeg
|
|
|
|OK, lets define URT before we go any further.

How can you define something when you apparently don't understand what bikes are URTs?

If you defined it as variable |BB-saddle distance, then yes, it would be a URT. But titanium
monstrosities |are not comparable to pivot based bikes made with relatively inflexible |materials.

Again, you are discussing things that you apparently have no experience with.

From the fact that it is ti and a look at the layout, I think I |get the basic principal of how it
works*. Calling this bike a URT would be |like cutting the seatstay out of a Scalpel or Unicoi (or
most hardtails for |that matter) and redefining them as URT bikes.

Uh, you're just digging yourself deeper and deeper.

I would define unified rear |triangle as a pivot based bike with the BB on the rear triangle. In
this |definition of URT, when you get out of the saddle, you are standing on the |rear triangle
and holding on to (in a roundabout way) the front triangle.
|
|
|
|*It appears to be a big leaf spring. When you sit on it, you add a
|considerable preload and thus it is not very active.

Uh, again, you're just digging yourself deeper and deeper.

When you stand, you |are unloading that preload. It looks clever. Has anyone here ever ridden |one?
Nevertheless, IMHO, it is inappropriate to label this thing URT.

LOL.

Educate yourself:

http://www.math.chalmers.se/~olahe/Bike/Rear/urt.html

http://www.titusti.com/techtalk.html

http://www.geocities.com/MotorCity/Flats/3877/fullsus.html

To answer your question, yes, I'm pretty sure that someone in this NG has ridden a Bow Ti.

 

[Dave Stocker]

"P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
news:[email protected]...

> When you stand, you |are unloading that preload. It looks clever. Has anyone here ever
ridden
> |one? Nevertheless, IMHO, it is inappropriate to label this thing URT.
>
> LOL.
>
> Educate yourself:
>
> http://www.math.chalmers.se/~olahe/Bike/Rear/urt.html

Says: "This category of bikes is, or at least used to be, characterised by the fact that the rear
triangle and the bottom bracket is one unit, connected to the main triangle via one pivot point. I
say used to be since there are some newer designs (like Kona) that still puts the bottom bracket on
the swingarm but also uses a linkage between the swingarm and the shock. I will call this new design
"linked URT" and the old design just URT. URT's are also called "floating drivetrain"."

>
> http://www.titusti.com/techtalk.html
Says: "The basic idea behind all unified rear triangle designs is to isolate the drivetrain from the
forces of the suspension. There are two basic types of unifieds: Sweet Spots and low pivots. Sweet
Spot designs do a good job of eliminating any pedal or rider induced suspension movement. On Sweet
Spot Unifieds, the suspension is fully-active while the rider is seated and becomes less active when
the rider stands up. Most builders of unified designs focus their design towards cross-country
rather than down hill. On Sweet Spot designs, there is a large change in seat to pedal distance as
the suspension goes through its travel. This occurs because the seat and cranks are on separate
moving parts of the frame and the pivot is approximately midway between these two points. You will
not experience any Bio-pace or DISC on a Sweet Spot unified design."

>
> http://www.geocities.com/MotorCity/Flats/3877/fullsus.html
Says: "The unified rear triangle (URT), or floating drivetrain, is a rear suspension design whose
popularity is waning in the current climate of downhill and freeriding.

The basic premise of this type of design is to isolate the rear suspension's effect on the
drivetrain by placing the entire drivetrain on the swingarm itself. Thus, the various components of
the drivetrain move together as the suspension compresses and extends. This eliminates any chain
reaction and can also allow for a very clean, simple suspension configuration consisting of a single
large pivot and a directly driven shock.

The inherent problem with this design is that the rider is in effect standing on the swingarm.
This is less of a problem when the rider is seated, but the natural tendency when going over
larger obstacles, rough terrain, or technical sections is to stand up, rendering the rear
suspension almost useless. The flip side to this effect is that during sprinted or climbing out of
the saddle, the suspension's lack of movement is considered a bonus, as less energy is wasted in
suspension movement.

There have been several very popular URT bikes in the past, most notably the Klein Mantra, the
Trek/Gary Fisher Y-bikes, and the Ibis Sweet Spot. There have also been twists on the URT design in
the form of the GT iDrive and the Paul Turner desiged Maverick."

LOL! This is all consistent with what I said.

but from http://www.castellanodesigns.com/diff.html "While developing the Sweet Spot suspension,
John became intrigued by the idea of incorporating spacecraft-style pivotless flexures into his
long-travel suspension system, and began modeling and testing pivotless prototypes. This work
culminated in the Ibis BowTi, the ultimate expression of his Sweet Spot Suspension. With 5" of
travel and no pivots, the titanium BowTi is in a class by itself. Castellano's next inspiration led
to the SilkTi and Ripley softails, also built by Ibis, featuring John's pivotless Flat-Plate
chainstays and Critically Damped Elastomer shock."

So the bow tie is considered a variant of URT. More importantly, the guy who designed it did so with
the intention of building a pivotless high pivot bike.

So I stand corrected about the Bow Ti. But I still maintain that it is a titanium monstrosity! ;-)

-Dave

 

[Dave Stocker]

"P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
news:[email protected]...
> |
> |*It appears to be a big leaf spring. When you sit on it, you add a
> |considerable preload and thus it is not very active.
>
> Uh, again, you're just digging yourself deeper and deeper.
>
> When you stand, you |are unloading that preload. It looks clever. Has anyone here ever
ridden
> |one? Nevertheless, IMHO, it is inappropriate to label this thing URT.
>
> LOL.
>
> Educate yourself:

My finite element analysis is a bit rusty and I do not know the relative elastic properties of the
stays that run from the head tube to the rear hub (what would they be called on this bike?), the
chainstays and the "seat tube", but I still think this is a reasonable approximation unless I am
missing some secret ingredient.

So if I am wrong in my assumptions about how this thing works, then I ask you: How does it work?

-Dave

 

[Dave Stocker]

I wrote:
> Standing on the swingarm does essentially causes the rear to have two spring rates where the
> difference in k is proportional to the distance
from
> BB to pivot.

Sorry, this is a mistake. If the hub moves x0, the BB moves x1, the shock compresses x2, the shock
has spring constant k a the rider wieghs R, then the work done would be:

W=x1*r+k*x2^2

This is not delta k, nor is it preload. It is more like additional unsprung wieght.

-Dave

 

[R.White]

P e t e F a g e r l i n <[email protected]> wrote in message
news:<[email protected]>...

>
> For example, the URT principle involves a constantly changing BB to saddle distance. This is not
> specific to a particular design, but rather to all URTs..

GT's I-Drive eliminated that problem. Maybe. Don't really know. I guess all they eliminated were
themselves.

 

[P E T E F A G E]

On Thu, 26 Jun 2003 08:57:49 +0200, "Dave Stocker" <[email protected]> wrote:

|"P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
|news:[email protected]...
|
|> When you stand, you |are unloading that preload. It looks clever. Has anyone here ever
|ridden
|> |one? Nevertheless, IMHO, it is inappropriate to label this thing URT.
|>
|> LOL.
|>
|> Educate yourself:
|>
|> http://www.math.chalmers.se/~olahe/Bike/Rear/urt.html
|
|Says:
|"This category of bikes is, or at least used to be, characterised by the
|fact that the rear triangle and the bottom bracket is one unit, connected to |the main triangle via
one pivot point. I say used to be since there are some |newer designs (like Kona) that still puts
the bottom bracket on the swingarm |but also uses a linkage between the swingarm and the shock. I
will call this |new design "linked URT" and the old design just URT. URT's are also called
|"floating drivetrain"."

Apparently you missed this part:

"Unified Rear Triangle (URT) "

"Placements ranges from very close to the BB (Trek/Gary Fisher) to in the middle of the downtube
(John Castellianos patented "Sweet Spot" on for example Schwinn, Ibis)"

The Bow Ti is a URT.

|> http://www.titusti.com/techtalk.html
|Says:
|"The basic idea behind all unified rear triangle designs is to isolate the
|drivetrain from the forces of the suspension. There are two basic types of |unifieds: Sweet Spots
and low pivots. Sweet Spot designs do a good job of |eliminating any pedal or rider induced
suspension movement. On Sweet Spot |Unifieds, the suspension is fully-active while the rider is
seated and |becomes less active when the rider stands up. Most builders of unified |designs focus
their design towards cross-country rather than down hill. On |Sweet Spot designs, there is a large
change in seat to pedal distance as the |suspension goes through its travel. This occurs because
the seat and cranks |are on separate moving parts of the frame and the pivot is approximately
|midway between these two points. You will not experience any Bio-pace or |DISC on a Sweet Spot
unified design."

"UNIFIED REAR TRIANGLE DESIGNS:"

"SOME COMPANIES THAT USE THE UNIFIED SWEET SPOT DESIGN: CATAMOUNT, IBIS, KLIEN, SCHWINN, WTB."

The Bow Ti is a URT.

|> http://www.geocities.com/MotorCity/Flats/3877/fullsus.html
|Says:
|"The unified rear triangle (URT), or floating drivetrain, is a rear
|suspension design whose popularity is waning in the current climate of |downhill and freeriding.
|
|The basic premise of this type of design is to isolate the rear suspension's |effect on the
drivetrain by placing the entire drivetrain on the swingarm |itself. Thus, the various components of
the drivetrain move together as the |suspension compresses and extends. This eliminates any chain
reaction and |can also allow for a very clean, simple suspension configuration consisting |of a
single large pivot and a directly driven shock.
|
|The inherent problem with this design is that the rider is in effect |standing on the swingarm.
This is less of a problem when the rider is |seated, but the natural tendency when going over larger
obstacles, rough |terrain, or technical sections is to stand up, rendering the rear suspension
|almost useless. The flip side to this effect is that during sprinted or |climbing out of the
saddle, the suspension's lack of movement is considered |a bonus, as less energy is wasted in
suspension movement.
|
|There have been several very popular URT bikes in the past, most notably the |Klein Mantra, the
Trek/Gary Fisher Y-bikes, and the Ibis Sweet Spot. There |have also been twists on the URT design in
the form of the GT iDrive and the |Paul Turner desiged Maverick."
|
|LOL! This is all consistent with what I said.

How can it be consistent with what you said, when you claim that the Bow Ti should not be labeled as
a URT, and each article shows that the Bow Ti is a URT?

How can it be consistent with what you said when you claimed :

"| Only active if rider remains seated (rider stands on swing arm when out of |saddle)"

...and the articles make this assessment:

"On Sweet Spot |Unifieds, the suspension is fully-active while the rider is seated and |becomes less
active when the rider stands up"

Hmnmm, that sounds familiar....oh yeah, that's what I wrote here:

">Perhaps "immune" is a strong word, but standing does act as a lockout.

Not on all URTs."

...and here:

">> |- Only active if rider remains seated (rider stands on swing arm when out
>of
>> |saddle) <bad?>
>>
>> Not necceessarily.
>>
>
>Actually true.

Actually false. The Ibis Bow Ti is active when you are out of the saddle. Less active than when you
are seated, but active nonetheless."

...etc., etc.

Apparently you are suffering from Googlitis coupled with a dose of assumptionitis.

|
|but from http://www.castellanodesigns.com/diff.html
|"While developing the Sweet Spot suspension, John became intrigued by the
|idea of incorporating spacecraft-style pivotless flexures into his |long-travel suspension system,
and began modeling and testing pivotless |prototypes. This work culminated in the Ibis BowTi, the
ultimate expression |of his Sweet Spot Suspension. With 5" of travel and no pivots, the titanium
|BowTi is in a class by itself. Castellano's next inspiration led to the |SilkTi and Ripley
softails, also built by Ibis, featuring John's pivotless |Flat-Plate chainstays and Critically
Damped Elastomer shock."
|
|So the bow tie is considered a variant of URT.

NO. The Bow Ti, and all Sweet Spot bikes, are URTs.

You assume that there is only one type of URT, when in fact they come in many flavors, depending
upon where the pivot point is located.

More importantly, the guy |who designed it did so with the intention of building a pivotless high
pivot |bike.

...that is/was a URT.

 

[P E T E F A G E]

On Thu, 26 Jun 2003 11:21:35 +0200, "Dave Stocker" <[email protected]> wrote:

|"P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
|news:[email protected]...
|> |
|> |*It appears to be a big leaf spring. When you sit on it, you add a
|> |considerable preload and thus it is not very active.
|>
|> Uh, again, you're just digging yourself deeper and deeper.
|>
|> When you stand, you |are unloading that preload. It looks clever. Has anyone here ever
|ridden
|> |one? Nevertheless, IMHO, it is inappropriate to label this thing URT.
|>
|> LOL.
|>
|> Educate yourself:
|
|My finite element analysis is a bit rusty and I do not know the relative |elastic properties of the
stays that run from the head tube to the rear hub
|(what would they be called on this bike?), the chainstays and the "seat
|tube", but I still think this is a reasonable approximation unless I am |missing some secret
ingredient.
|
|So if I am wrong in my assumptions about how this thing works, then I ask |you: How does it work?

As noted before, when seated it is quite active, contrary to your claim, and when standing, it is
considerably less active, but active nonbetheless, also contrary to your claim.

 

[Spider]

[email protected] wrote in message news:<[email protected]>...
> "Dave Stocker" <[email protected]> wrote in message
> news:<[email protected]>...

<snip>

> > What I tried to say in my original post was that URT, like any other suspension type, has its
> > pros and cons and it has its niche. When people say URT sucks, they are usually extrapolating
> > the shortfalls of a particular design to the principle.
> >
> > -Dave
>
>
> Thanks for the informative post Dave

You had to quote that whole damn thing to write six words of "me too?"

Sheesh.

Spider

 

[Sorni]

"Spider" <[email protected]> wrote in message
news:[email protected]...
> [email protected] wrote in message
news:<[email protected]>...
> > "Dave Stocker" <[email protected]> wrote in message
news:<[email protected]>...
>
> <snip>
>
> > > What I tried to say in my original post was that URT, like any other suspension type, has its
> > > pros and cons and it has its niche. When
people
> > > say URT sucks, they are usually extrapolating the shortfalls of a
particular
> > > design to the principle.
> > >
> > > -Dave
> >
> >
> > Thanks for the informative post Dave
>
> You had to quote that whole damn thing to write six words of "me too?"

And this surprises you...why?

Bill "whaddya, new?!?" S.

PS: Totally agree with your sentiments, Peter Parker; just given up on pointing 'em out to the ones
who do it...

 

[Dave Stocker]

"P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
news:[email protected]...
> Apparently you missed this part:
>
> "Unified Rear Triangle (URT) "
>
> "Placements ranges from very close to the BB (Trek/Gary Fisher) to in the middle of the downtube
> (John Castellianos patented "Sweet Spot" on for example Schwinn, Ibis)"
>
> The Bow Ti is a URT.
>

No I did not miss it. Just because Ibis used Castellianos' "Sweet Spot", it does NOT automatically
follow that the Bow Ti is a URT.

<snip more of the same>

> |
> |The inherent problem with this design is that the rider is in effect |standing on the swingarm.
> This is less of a problem when the rider is |seated, but the natural tendency when going over
> larger obstacles, rough |terrain, or technical sections is to stand up, rendering the rear
suspension
> |almost useless. The flip side to this effect is that during sprinted or |climbing out of the
> saddle, the suspension's lack of movement is
considered
> |a bonus, as less energy is wasted in suspension movement.
> |
> |There have been several very popular URT bikes in the past, most notably
the
> |Klein Mantra, the Trek/Gary Fisher Y-bikes, and the Ibis Sweet Spot.
There
> |have also been twists on the URT design in the form of the GT iDrive and
the
> |Paul Turner desiged Maverick."
> |
> |LOL! This is all consistent with what I said.
>
> How can it be consistent with what you said, when you claim that the Bow Ti should not be labeled
> as a URT, and each article shows that the Bow Ti is a URT?
>

The seated vs standing part is consistent with what I said. As I said earlier, there was no specific
mention of the Bow Ti in any of these. But this is a moot, bucause I already said in my last post
that I now agree that the Bow Ti is a URT. So what is the problem?

-Dave

 

[Dave Stocker]

"P e t e F a g e r l i n" <[email protected]> schrieb im Newsbeitrag
news:[email protected]...

> |
> |So if I am wrong in my assumptions about how this thing works, then I ask |you: How does it work?
>
> As noted before, when seated it is quite active, contrary to your claim, and when standing, it is
> considerably less active, but active nonbetheless, also contrary to your claim.
>

Ok, you said this a couple of posts ago:
>Actually false. The Ibis Bow Ti is active when you are out of the saddle. Less active than when you
>are seated, but active nonetheless.

I misread this as:
>Actually false. The Ibis Bow Ti is active when you are out of the saddle. Less active when you are
>seated, but active nonetheless.

So I understood a claim that it was more active out of the saddle than in
it. This went against my understanding of how URT works and was scratching my head coming up with a
reason it could be so. So now that that is out of the way, we can safely say it acts like every
other URT: less active out of the saddle than seated.

I think it is possible to generalize quantitatively how pivot location and rider wieght affect how
the suspension acts, but I want to sleep first.

-Dave