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So I will rethink the Geo of a Frame I´m going to build.
Thanks
IMO short CS don't suck they just aren't for everyone.
Moto dudes get their suspension done, MAYBE. Heaps don't set their sag, measure their pressures etc. They just hop on and go.
So given that, it's odd to me that something simple like chainstays that had a range of adjustment the same as a moto bike isn't a normal practice. Sure, there is bracing if the normal moto way was used, but surely an adjustable solution is out there?!
Bicycles with sliding dropouts have limited feel within the range of adjustability. It was first shown to have DH racebikes fit a tighter track. The few bikes with the feature show how small the acceptance level was found to be. The feature on an MX bike has more a effect upon keeping the front of the bike down under power - or the inverse on very short, tight, supercross style racing.
Is that a personal picture in your forum signature??
For moto it has a massive effect on stability and cornering... basically nothing serves for anti-wheelie. Body positioning and throttle control are the real culprits there.... But the longer wheelbase will help stability down a rough straight away and kill headshake... whilst the shorter is good for slotting into ruts or cutting down in a turn.
The picture is a good representation of my size, I do have better colour tho.
250 vs 450 have huge swingarm differences? 2 strokes may be making a comeback I've heard - these are even smaller then?
So what effect would length had had for Ken Roczen at Anaheim last weekend??
Kenny crashed because he went slightly long/fast into a rutted pocket transition, was slightly off-balance to the right and caught his right foot on the rut, flinging it up... Not shock or anything else. People theorising the new bike isn't sorted are way off base. Not the first time that sort of crash has happened in SX...
So, as someone who is getting back to MTB, what are the common adjustments? Head angle? Rake/Trail via cups? Travel?
Again, I go back to my ski analogy. There are a few bindings out there that move front to back with the switch of a lever. This changes your ski's "front center" (if you will). Cool idea, but if your skis are mounted in the right spot to begin with you really don't need to move this as being used to a "balanced" mount (when considering your own ability to properly weight the ski) is most important.
With mountain bikes, if the bike was designed more "in proportion" to begin with, a rider could tweak static weight distribution with stem length, handlebar height, headset adjustment, offset bushings etc. to fit his style and taste.
These tweaks can make a notable difference, but if rear center is way off when considering riding style, body type, etc, you'll always be riding a bike that is a compromise, at least from my POV.
I finally built my custom bike/frame that, as I think, is "in proportion"
It´s at the more extreme end of geometry, but balanced, and it feels great.
It needed some time to completely find it´s sweetspot.
I went through travel adjustments by the fork (it´s a hardtail),rotated and lengthened the bars, switched stems, etc.
I will try more adjustments, just for curiosity. But it´s already good. Very fast and stable at higher speeds.
After this thread started and I started reading the CSs in my CAD drawings began to grow.
Now I ended up with this geo with 29" front/ 27.5" rear and 120mm fork travel.
WB 1320mm
CS 445mm
reach 520mm
stack 640mm
HT° 62.8°
SA° 75°
BB -36mm
I´m 6ft 4" tall.
Thanks for the input!
Here are some guides that might be helpful as you dial things in:
http://www.vitalmtb.com/features/Vital-MTB-How-To-Cockpit-Set-Up,1490
http://www.vitalmtb.com/videos/features/How-To-Mountain-Bike-Cockpit-Se…
http://www.vitalmtb.com/photos/features/How-To-Get-The-Most-Out-Of-Your…
http://www.vitalmtb.com/videos/features/How-To-Mountain-Bike-Suspension…
http://www.vitalmtb.com/tags/how-to_instruction_vital_feature
Almost every component can be tweaked to suit your preferences. Unlike moto, which seems to be pretty standardized for the common guy, MTB has a ton of variety. Some concepts/products are very rad for most riders while others have limited purpose.
As far as bike geo adjustments, it's common for some frames to have a simple "flip chip" design that allows you to change the head angle and bottom bracket height. Like this:
Other designs allow you to change the travel or how the travel is utilized (adding more progression, for example).
Chainstay adjustments are becoming less of a thing these days, though some frames do have adjustability.
Dirt jump and slopestyle bikes often have sliding dropouts, much like motos, primarily to help with chain tension but also to alter the ride feel.
Cane Creek makes the AngleSet which allows you to play with the head angle if your headtube is compatible.
Forks are sometimes offered with different offset values depending on your steering preferences, and some suspension centers will swap the crown/steerer assembly to achieve different numbers for discerning riders.
Definitely put some trust into the Product Managers who spec complete bikes, especially at reputable brands, as they've done a lot of the riding/testing/research for you. Given enough time on enough bikes you'll start to really hone in on what works best for you and your riding style.
I find that when i had my Devinci Wilson Carbon 2013 and my current Scott Gambler 710 2016, i tend to jump over more of the rough stuff.
When i had my Nukeproof Scalp 2012 and A Giant Glory 0 2015 i just deathgripped and plowed through.
Had the same feeling on my enduro bikes, MDE Damper with 445mm vs Patrol Carbon with 430mm
I go faster on short chainstay because of this.
We're agonizing over a few millimeters, obsessing over "perfect" balance on all trail gradients, and getting positively worked up over 0.6" (15 mm), but no one is talking about what's happening at the front.
A typical 6" bike can lose over 50 mm (2") of front-centre length as the fork tucks under at full compression (ignoring fork flex, which makes it even worse). The head angle can steepen by 7° at full pitch (front compression without rear compression). And these things happen precisely when you don't want the front end to get short and steep. Then, just to add to the misery, the front end lengthens and slackens when your weight shifts rearward on climbs. The slack head angles of "aggressive" bikes make this shortening/steepening effect even more dramatic.
I'm not saying chainstay length is irrelevant; I'm just saying there's a bigger problem and we seem to accept it as inevitable.
Can go on for a while on this topic, but the gist to take out of the debate is: horses for courses, and that a more complete holistic design that compromises least among all various performance targets will be an overall superior performer. One problem is that people customize their bikes all sorts of ways that can upset a holistic design (ex. Intense Primer and the JS-tuned concept, being "custom built" ignoring recommendations). And the real elephant in the room: another problem is the pilot, and how he tries to handle the bike the way he wants, rather than tries to get to know the bike and work with it--the more you know the bike, the easier to get it to ride at its limits and much less likely you'll complain about minor shortcomings (major shortcomings are another story).
In the end, a really well engineered bike, with lots of details gone over with a fine comb to refine it, will earn close to a 5 stars on a review no matter the cs length. You have to accept that some reviewers in the media have little knowledge of such in-depth things in designing a bike, but they're like anyone else in that they can get a feel from a bike from riding it a while. The difference is that they have a higher bar from riding the best of the best, have talked to many industry insiders, and have seen more of the world. They're not super in-tune with bikes, nor how they're painstakingly they're created--you can see it in questionable comments that don't seem obviously wrong like "a 140mm travel bike will have more travel in reserve after big hits than a similarly designed 120mm bike." This kind of misinformation misled lots of people into thinking they should opt for more travel, as well as their comments like "short chainstay makes the bike snappy/fun/etc." making long chainstay bikes less desirable. This is a disservice to the industry and as I've found in all communities I'm a part of, allowing such ignorance/stupidity to spread will directly lead to an increasingly toxic community. It's not any few variables like the chainstay length that make the bike, it's all the variables (inc. chassis stiffness, susp kinematics, ideal rider type), and how they're made to work together that makes the bike.
Listening to people who argue about simple #s, who demonstrate that they can't see the whole picture, would be like listening to the guy who can only get a job making french fries or some other simple physical labor (needing little education) and spending a large part of their earnings on alcohol, premium food, and "luxury" that was made popular by pop culture, and actually being convinced that they know topics like politics/government, tech, etc. They have a iPhone, a sports car, good circle of friends, or some other measure of success, he's gotta know something right, eh? "Nerds" that do mass research, have very few (but very close) friends, don't know much of anything else but their passions, constantly pick fights over "trivial" things are to be avoided, and any measure of their success can be ignored, since almost anyone can get them, eh?
Basically, if you have a checklist of 5 characteristics you want to be excellent in something, and then later increase that checklist to 8 characteristics, you will end up with a more refined object. Good designers probably consider dozens, maybe hundreds of such characteristics in their designs, while poor designers will focus on a few. Good designers know no limit, and keep improving and only put inventions out onto market to fund further improvements to them, as long as they know that it will be competitive. Godly designers do the same, but make it extremely affordable with minimal compromise.
I would also argue this is why it is so important to setup your suspension properly.
Maybe someone can create some sort of neutralizing headset that works on a gimbal or something. lol. Keeps all angles static at all times. Hey, its possible and I'm sure it'd be a trip to ride.
Until then, elephant or not, there isn't much we can do about it. Hence, why I focus on things we can do something about - like static weight distribution (the real reason I got into the chainstay rant)
Cuts deep!
I will say whoever you are, I'll buy you a beer if I ever meet you for such a well crafted post, touching on so many of societies ills while somehow bringing it back to bike geometry. In a word, incredible.
Just to be clear, because I often am not, I don't believe chainstay length is the end all be all, I believe the entire package "makes" or "breaks" the ride, and part of this is the way the rider weights the two tires in a neutral position. This is going to be vastly different, if we keep the rear end the same length, on a small as it would be an XL.
This is why a short rider on a smaller frame may find the bike "incredibly balanced" whereas a tall rider may not. Or maybe that tall rider likes rearward weight bias like your Porsche analogy. Either way, only way to know is for you, as a rider, to ride said bike and make his own decision...
Oh, and once you find something you like, throw it on two scales and get that distribution on paper for future bikes!
There are two key takeaways here...
1) custom bikes have a place.
2) listening to your body, your own experience, and not the trends conjured up on the internet will likely yield the most enjoyment on a bike.
It's like casting a vote, posting to the internet about what your views are, no matter how shallow/ignorant, as long it's connected with a certain belief in question, as if that would help make the belief ring truer. No one likes the "depends" answer, since explain the why and how behind it tends to lead to a wall of easily misunderstood text, that later gets quoted out of context.
Would love if people used cars as a way to describe a bike they wanted. I want a bike that provides a similar experience to a Honda Accord. Would love to hear what people suggest to that. I ride a Yeti SB5c, but used to ride a Thunderbolt that I could say feels more like a Mazda 3.
I do however know skis, and I know them well. So that's where I can (and do) make analogies often. A lot of this particular rant came from skiing.
End of the day, as you alluded to, the only thing that is "this way" or "that way", is the absoluteness that just about everything resides in the grey area...
(see what I did there?)
J
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