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The reason why Geometery might actually matter more than anything else.

post #1 of 28
Thread Starter 

MTB geometery is ever evolving, and sadly so many companies are still far behind the curve. Many companies are still fitting their MTBs with short front centers(distance from crank to front wheel), longer than needed front ends and steep head angles. 

 

It hard to argue that short stems and wide bars do make a bike easier to lean over and slow the steering down to make the bike more stable.  the issue is just slapping a short stem and wide bars on your short front center , long chain stay bike and now you just going to feel like you are going to go over the bars. The bike has to be designed that way to begin with, 

 

Here are some video from people who ride far more different bike than me. I like how they go on to say how middle aged people who lack skills would gain skills by riding a bike with this style geometery.

 

 

 

for the hardtail fans.

 

 

more from the bike mags guy talking to arguable the biggest major company to be making bike that just work in technical terrain. I honestly do not care for their suspension but i am glad they are doing this, other companies will follow suit.

 

 


Edited by Josh Matta - 7/4/14 at 7:31am
post #2 of 28

@Josh   I will watch these later.  thanks

 

Can you explain this?  The structure is "cumbersome"  :D so I am not really sure of what you are saying; are short stems and wide h-bars good or not?  I think you are saying   "short stems and wide handlebars make leaning and bike over more difficult but make the bike more stable? 

 

"It hard to argue that short stems and wide bars do not make a bike easier to lean over and slow the steering down to make the bike more stable."

post #3 of 28
Thread Starter 
Quote:
Originally Posted by Finndog View Post
 

@Josh   I will watch these later.  thanks

 

Can you explain this?  The structure is "cumbersome"  :D so I am not really sure of what you are saying; are short stems and wide h-bars good or not?  I think you are saying   "short stems and wide handlebars make leaning and bike over more difficult but make the bike more stable? 

 

"It hard to argue that short stems and wide bars do not make a bike easier to lean over and slow the steering down to make the bike more stable."

 

 

so I should have left out the "not"

 

I went back and reeditted thee OP.

 

short stems and wide bars are great......but only if the frame was designed with that in mind. The issue the majority of bike maker kind of suck at making fun to ride bikes that can be used by pro and inspire novices a like.

post #4 of 28
Josh, besides Kona and Niner, who else has got the right idea with frame geometry?
post #5 of 28
Thread Starter 
Quote:
Originally Posted by FairToMiddlin View Post

Josh, besides Kona and Niner, who else has got the right idea with frame geometry?

 

 

I would nt say even Kona and Niner have it.....they do have it on certain models.... though. I would say that no one truly has it across the whole product line and I think even XC bike could benefit from this geo.

 

Evil bikes

Mondaker

Giant's Newest Trances 2014 and up are great, their older offerning suffer from short front centered and long chain stays. The new 650b reign will be great as well.

Newer Santa Cruz

Newer PIvot

Newer Rocky Mountain Altidude, Slayer, Instinct....

Intense for quite a while

 

 

there are lots in recent years that are coming with longer front centers, short stays and slack head angle

 

 

 

post #6 of 28
So individual 'human' geometry plays no role?
post #7 of 28

yeah, really like what I am seeing from Santa Cruz and Pivot (and others building similar bikes) the New Trek Fuel EX8 too.  That 73* Seat and 68- 68.5 Head and a 430ish CS is what I am drawn too for an all mountain bike that fits somewhere between the endure and XC class.  

post #8 of 28
Thread Starter 
Quote:
Originally Posted by markojp View Post

So individual 'human' geometry plays no role?

 

 

well yes.....

 

but once a rider is off the saddle it surprising how much the shape of the ride does not matter.....assuming a frame size similar to what they should be on.

post #9 of 28
Thread Starter 
Quote:
Originally Posted by Finndog View Post
 

yeah, really like what I am seeing from Santa Cruz and Pivot (and others building similar bikes) the New Trek Fuel EX8 too.  That 73* Seat and 68- 68.5 Head and a 430ish CS is what I am drawn too for an all mountain bike that fits somewhere between the endure and XC class.  

 

has a ton to with top tube lenght as well..

post #10 of 28
So explain that a little more if you could. I see more emphasis on the tt than seat tube /frAme height for sizing which is more accurate for fit but how about an example using a pivot or sc? I guess I am looking for better example than just frame size relative to ETT
Edited by Finndog - 7/4/14 at 11:16am
post #11 of 28
Quote:
Originally Posted by Josh Matta View Post
 

 

 

well yes.....

 

but once a rider is off the saddle it surprising how much the shape of the ride does not matter.....assuming a frame size similar to what they should be on.

 

 

But all of a sudden handle bar height and TT length certainly matter... a lot when you're at getting that last 5%. 

post #12 of 28

Scott is making some very cool bikes that seemingly aren't available in the US.  I also think the BMC's are a viable design. A lot for the money. 

post #13 of 28
Quote:
Originally Posted by markojp View Post

So individual 'human' geometry plays no role?

 

 

Quote:
Originally Posted by Josh Matta View Post
 

 

 

well yes.....

 

but once a rider is off the saddle it surprising how much the shape of the ride does not matter.....assuming a frame size similar to what they should be on.

I'm definitely going to have to ponder this a bit the next time I'm on my bike.  

I know that I spent a lot of time trying bikes and had it narrowed down to a SantaCruz and the Trek Fuel8W that I ended up getting.  Both of those bikes seemed to have the geometry that I liked. 

But that was 6ish  years ago. 

post #14 of 28
Thread Starter 
Quote:
Originally Posted by Trekchick View Post
 

 

 

I'm definitely going to have to ponder this a bit the next time I'm on my bike.  

I know that I spent a lot of time trying bikes and had it narrowed down to a SantaCruz and the Trek Fuel8W that I ended up getting.  Both of those bikes seemed to have the geometry that I liked. 

But that was 6ish  years ago. 

 

 

Santa Cruz have gotten better but not great really depends on what you are looking at and how much reach you need while sitting while climbing.  The new trek trail and burlier bike have great geo...

 

The Santa Cruz have a far superior suspension but if you watched the Kona/bike mag video you would see how Dual short links can be detrimental to good geo. My own Giant Anthem 29er suffers from this....... 

 

Basically what I am saying is you should buy a frame around what bars and handle bars you want to/(should be riding), IE I think you personally should be on a Medium frame from most bike manufactors with shorter stem/wider bars. The problem is most M out of the box might feel to large with out the proper stem. IE you saw how tall Diane was I set her up on a Medium Trance X with a 50mm stem. Bike fit like a glove and will feel a ton more stable than the shorter small. Giant has lenghten their top tubes with 2014 Trance X 27.5 redesign. 

 

With the advent of dropper post, Kona is on to something just making the top tube super low slung. With the seat dropped you can move you COM in any which way you want meaning that all of the sudden ETT and seat post angle are not really going to matter..... Only handlebar height, front center and chainstays really will. 

 

One of my biggest Pet Peeve in the bike industry right now is Women Specific Design. A women does have short torso yes. Which will matter in bike sizing while sitting yes. but most companies are shorterning their already short front center and fitting the bike with the same stem as the men's bike basically not only making the bike harder and less fun to ride, but also making it less stable.  Giant is very much Guilty of this. 

 

let compare the bikes that Giant has a medium Trance to medium Intrigue both are 5.5 inch travel bike. One is unisex and the other is women specific. Just for fun let compare these both to medium Process 134 which is one of the bike discusses in the videos.

 

 

 

                            Trance M                          Intrigue  M                        Process 134   M           Honzo M (the bike that inspired me  start this post in the first place)

 

 

Head Tube Angle     67                                  68                                   68                               68

Chainstay Lenght    17.3                             17.6                                  16.7                             16.3                         despite the honzo being a 29er its got the shortest stays.....

Top Tube                23.6                              22.8                                 23.6                             24.02

Wheelbase             45.5                              44.4                                 45.0                             44.1

Front Center           28.2                              26.2                                 28.3                             28.1

Stand Over             28.1                              28.2                                 25.98                            32                             this does not seem right to me ......

 

so some interesting thing s are quiet clear when looking at these numbers. The Intrigue is the easiest bike on this list to endo do to it short front center, and long chainstays, will feel the most unstable, be the hardest to manual/wheelie due to its longer chainstay. it also have the highest stand over which is kinda of like really?  Just because a women's body is different does not that bike any easier to ride for her except arguble while climbing and sitting down........ If anything that bike might actual kill confidence compared to the Trance or Process 134......

 

 

Comparing the 2 men's bike which are quite similar in scope and purpose. 

 

The process despite being slightly shorter in wheelbase actually has a longer front center. I have not spent anytime on the process but I have trail ridden a Medium and a large Trance as well I own the process hardtail step sibiling the Honzo.  After a week of riding the Honzo all i can say is I am amazed that a hardtail(or any bike)  can handle like that. I had hunch buying it, which is why I bought it but just wow. The New trance 650b bike feel very similar in feel and I love Maestro suspension...... but I am more than curious about how the shorter chain stay single pivot bikes feel now. 

post #15 of 28

Speaking of ETT, is the actual center of Hbar distance to seat post more or less important than the center of the steerer tube distance?  Basically, is the measured ETT as important as the actual reach to the H-bars?  This certainly comes into play when selecting stem length in con junction with Hbars.   A 740 9* backsweep with a flat or 5* rise is going to position the rider differently than the same setup with a  720 9* 30Riser bar.   

post #16 of 28
Thread Starter 

finn what i am saying is the Actually top tube should be the right length to run a short stem.  

post #17 of 28

and that is determined how.  

post #18 of 28
Thread Starter 
Quote:
Originally Posted by Finndog View Post
 

and that is determined how.  

 

 

by riding bikes .

post #19 of 28
I don't know of it applies to mt bikes, but on road bikes, as a rule, short stems slow down the handling of a bike, and a long stem makes is 'twitchy'. Too short feels sluggish, too long a stem to 'correct' a too short top tube moves your CoM too far forward and like skiing, loosing balance and weight distribution between both wheels. Too far aft isn't good for climbing, but aft for descending works nicely, etc... Lots of tweaking for intended outcome and use. Can't imagine mt biking is all that different, but I'm not claiming any sort of expertise on the knobby tire side of things. smile.gif
post #20 of 28
Thread Starter 
Quote:
Originally Posted by markojp View Post

I don't know of it applies to mt bikes, but on road bikes, as a rule, short stems slow down the handling of a bike, and a long stem makes is 'twitchy'. Too short feels sluggish, too long a stem to 'correct' a too short top tube moves your CoM too far forward and like skiing, loosing balance and weight distribution between both wheels. Too far aft isn't good for climbing, but aft for descending works nicely, etc... Lots of tweaking for intended outcome and use. Can't imagine mt biking is all that different, but I'm not claiming any sort of expertise on the knobby tire side of things. smile.gif

 

 

short stems slow sdown the steering effort but speed ups and facilates  the leaning efforts. when you are 'steering" a mountain bike slower is far easy and there for makes it so when you go though chunky terrain your front wheel is less likely to be knocked off line due to the slower steering. IE slow steering is good, quick carving(ie leaning over) is good!   I find myself not losing anything on climbs by having the long top tube/short stem but the gains in technical terrain especially descending are really great. Yesterday out riding my Honzo I Personal Recorded several descents mostly the ones that have ton of tight twisty variable radius turns, and steep off cambered turns and the bike does not even have the right fork yet...... I attest this to tight chainstays and long front center letting me really lean the bike over at will. 

 

the entire point of this thread is that MTB even Xc Mtber need to stop looking at road bikes for fit... because there are not even close to same.  Longer stems in larger size make no sense at all. 

post #21 of 28
Quote:
Originally Posted by Josh Matta View Post
 

 

I find myself not losing anything on climbs by having the long top tube/short stem but the gains in technical terrain especially descending are really great.

 

Same here.  I was worried about it on the steeper climbs but if you get your weight forward properly it really doesn't make any difference.  Size wise I'm right on the cusp between M and L frames and I'm convinced that going with the larger frame and a shorter stem is the way to go.  I used to think being on the cusp of sizes was a disadvantage but I've come to realize that it gives me more options for customization.

 

And yeah, fitting for a road bike is an entirely different beast than a mountain bike.  They serve such different purposes there's no point comparing the fine points.

post #22 of 28
I figured as much. It's like comparing the geometry of GS skis to all mountain skisThe common issue to both is that geometry is important for any serious performance riding, and will be different according to use/focus/ "desired outcome... " (can't believe I just spit that one out. Kind of hate that phrase. smile.gif )
post #23 of 28
Thread Starter 
Quote:
Originally Posted by markojp View Post

I figured as much. It's like comparing the geometry of GS skis to all mountain skisThe common issue to both is that geometry is important for any serious performance riding, and will be different according to use/focus/ "desired outcome... " (can't believe I just spit that one out. Kind of hate that phrase. smile.gif )

 

 

I would say its more like comparing a skate ski to burly powder board with a touring binding :P. 

post #24 of 28

This is dumb. Everyone know that the only geometry that matters right now is: short chainstays! :D

post #25 of 28

Soon we will have mtbs with chainstays short enough to put the rear wheel in front of the (previously) front wheel, stems won't just be short, they will be BEHIND the steerer tube, and bars will be so wide that they will need motocross-style pads because your sternum will only be one inch away.  ;)

 

Seriously, there is a lot of good change going on in the mtb geometry world right now, but like everything, the latest good idea is often taken too far. For example, part of the move to shorter chainstays is to make the bike feel more playful which they do, but "playful" is a bit of a synonym for twitchy or unstable.  So, that is addressed in part by relaxing the front fork rake, making the bars wider, and the stem shorter.

 

But within reason there is a method to this madness.  My previous fun trail bike was a Turner Sultan which had classic geo with longer chainstays, a modestly raked fork angle, etc., and I recently switched to a new Trek Remedy.  It definitely IS more fun, and snappier, and flickable (that word needs to be banned), but all this does come at a modest expense to its ultimate high speed stability on very rough, fast trails.  It's a trade worth making to me, but a trade nevertheless.

post #26 of 28
Thread Starter 
Quote:
Originally Posted by HRPufnStf View Post
 

Soon we will have mtbs with chainstays short enough to put the rear wheel in front of the (previously) front wheel, stems won't just be short, they will be BEHIND the steerer tube, and bars will be so wide that they will need motocross-style pads because your sternum will only be one inch away.  ;)

 

Seriously, there is a lot of good change going on in the mtb geometry world right now, but like everything, the latest good idea is often taken too far. For example, part of the move to shorter chainstays is to make the bike feel more playful which they do, but "playful" is a bit of a synonym for twitchy or unstable.  So, that is addressed in part by relaxing the front fork rake, making the bars wider, and the stem shorter.

 

But within reason there is a method to this madness.  My previous fun trail bike was a Turner Sultan which had classic geo with longer chainstays, a modestly raked fork angle, etc., and I recently switched to a new Trek Remedy.  It definitely IS more fun, and snappier, and flickable (that word needs to be banned), but all this does come at a modest expense to its ultimate high speed stability on very rough, fast trails.  It's a trade worth making to me, but a trade nevertheless.

 

 

you did not get it..... you forgot lengthing the front center, and slakening the head angle. 

 

shortering the chainstay, while you lengthen the front center and slack out the front end will make the bike more stable and quicker to carve around.... 

 

On stems and handlebars it hard to argue that any frame that forces you to use a stem over 50mm is really that good. 

 

So has Kona gone to far then? 

post #27 of 28
Quote:
Originally Posted by Josh Matta View Post
 

 

 

you did not get it..... you forgot lengthing the front center, and slakening the head angle. 

 

shortering the chainstay, while you lengthen the front center and slack out the front end will make the bike more stable and quicker to carve around.... 

 

On stems and handlebars it hard to argue that any frame that forces you to use a stem over 50mm is really that good. 

 

So has Kona gone to far then? 

No, I get it, just didn't want to overcomplicate an already long post.

 

I've got a long torso, so I'm hugely in favor of lengthening the front center, as it lets me ride a correctly sized bike without the need for an overly long stem.

 

As far as slackening the HT angle, again, it's being done partially to compensate for the snappiness that the shorter chainstays bring.

 

My Remedy has a slacker HT than my old Sultan, while the Sultan has longer chainstays.  In terms of high speed, straight line stability in chunk, the Sultan, despite the slightly steeper HT, is the winner by a nose, while the Remedy, despite the slacker HT, is a bit more nimble.

 

I guess it just goes to show how the many, many bike geo variables interact, but at my LBS, one of the most common questions about an FS bike from potential purchasers this summer is "how long are the chainstays?".  Important?  Yes.  The whole picture?  Not even close. 

post #28 of 28

canceled post.  never mind......


Edited by Finndog - 8/23/14 at 8:29pm
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