New School Geometry Back In Time...

Some astute observations from another forum. I pretty much agree.

“For whatever reason I have been thinking a lot about the history and progression of geometry. Short stems couldn't really work without wide bars. Wide bars really don't work with small clamping diameters. Long slack bikes really don't corner or climb well without a steep seat angle. Steep seat angles kind of suck without dropper posts. Super long bikes would be flexy or really heavy without carbon or really good hydroformed aluminium. So if you went back 20 years and built a bike with modern geometry, it would probably suck and you would want that twitchy and nervous bike that would try to kill you if you weren't paying attention.”

I sort of agree. All that stuff is logical, but it doesn't really explain why DH bikes had such shitty geo for so long.

In short, my theory is that without really high quality suspension you need a steep, twitchy, responsive bike because all the work is being done by the rider. As bike tech got better - suspension, tires, bigger wheels - you really now wanted the bike to do the work, so it all get slacker and wider.

Or maybe we all just sucked back then. Could be.

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Originally Posted by beece

In short, my theory is that without really high quality suspension you need a steep, twitchy, responsive bike because all the work is being done by the rider. As bike tech got better - suspension, tires, bigger wheels - you really now wanted the bike to do the work, so it all get slacker and wider.

Or maybe we all just sucked back then. Could be.

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After riding a hardtail with modern geometry, I disagree with your theory.

I've been saying the same as OP's quote minus the carbon/hydroformed aluminum and plus the fact that steeper seat angles pedal better outright. Oversized aluminum is far from new so longer has been an option, but it needed the other stuff--and riders (and tires) using more lean angle to accommodate it.

I think there was also a minor impact from ditching the front derailleur, both because it tipped the scales for droppers and helped stabilize anti-squat so that people could actually notice bikes that pedal well. A lot of crap was foisted off on riders who couldn't really tell before (SpecialEd) and now with things coming together on so many fronts that's harder to do. Marketing was a big headwind.

Ultimately, I view this as a giving thanks for where we are now type of thing. Imagine how good they will be in 20 years.
I’ll be riding with an Oxygen/Nitrous tank mix on an ebike by then, though.

All good comments above. One thing not mentioned is BB height. I’ve noticed mfgers are finally shipping complete bikes with shorter crankarms and nicely low BBs.

There’s still relatively low awareness of the benefit of inherently larger BB drop with 29ers. Most of the blather focuses on the roll-over-chunk wagon wheel effect.

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Originally Posted by frorider

There’s still relatively low awareness of the benefit of inherently larger BB drop with 29ers. Most of the blather focuses on the roll-over-chunk wagon wheel effect.

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That's the only good thing about those abominations. :D


As far as 'requirements' for decent geometry, that's a bunch of horse puckey. There were a few moto companies dabbling in bicycles 30 years ago that were just building moto geometry steel hardtails and horrendous erector set suspension designs. Riding literally with 32" moto bars as well. People aren't aware because companies weren't smart enough to just make that stuff so they weren't putting it under their pro riders. I'm talking dh pros here, not that hybrid road riding thing that passed as mountainbiking for so long.

Tons of british hardtail welders these days are doing the same thing.

Yeah, like 'woo and toast said, we had a blueprint for geo that didn't suck all along. DH bikes never needed steep seattube angles or any of that to work, the industry just had its head up its ass and was progressing mountain bike geo by making incremental changes, starting from a road bike.

you didnt have to peddle a DH bike up hill either

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Originally Posted by HAB

Yeah, like 'woo and toast said, we had a blueprint for geo that didn't suck all along. DH bikes never needed steep seattube angles or any of that to work, the industry just had its head up its ass and was progressing mountain bike geo by making incremental changes, starting from a road bike.

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This.

I am sorta bitter / bemused by all the bullshit bandaids some of us had to use over the years to try to kluge the geo we wanted. Eccentric eyelet reducers, small rear wheel, anglesets,etc. I remember several single pivot bikes like my old Gemini that immediately rode a thousand times better once you drilled a shock mount hole in a slacker location (and slammed seat all the way fwd). How the fuck did these large bike companies not have test mules with a few hole location options to try on the trail?

And for taller riders, for years the industry basically said Here try this long ass stem rather than Hey it’s trivially easy to offer you a 500 mm reach aluminum frame so here you go.

If some major company produced a bike with modern geo and a 500mm reach in 1999, no one would've bought it. As much as that bike makes sense now, it took incremental steps for the money-spending public to embrace it.

Mondraker has been doing something akin to modern geometry for at least 5 years, but it's not like those things have been flying off the shelves. Same could be said for the original GG Megatrail - cult following, but didn't really enjoy wider acceptance.

To some extent, the speed-ification of trails probably contributed too. It's a lot easier for the average joey to enjoy their 1300mm wheelbase on the latest, greatest flow trail that doesn't have any slow, awkward tech in it.

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Originally Posted by toast2266

If some major company produced a bike with modern geo and a 500mm reach in 1999, no one would've bought it. As much as that bike makes sense now, it took incremental steps for the money-spending public to embrace it.

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Totally. Also, a 500mm reach slapped on a 1999 bike would have sucked. You do need to pair it with a slacker head angle, steeper seat tube angle, etc for all the modern trends to come together and actually work.

All I meant was that dirt bikes have been a better model to base mountain bike geo on for as long as mountain bikes have been a thing.

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Originally Posted by HAB

All I meant was that dirt bikes have been a better model to base mountain bike geo on for as long as mountain bikes have been a thing.

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But even the dirt bike companies didn't know that. Honda threw a shitload of money at the G-Cross program, but as best I can tell, that bike still had pretty typical geo numbers for 2004.

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Originally Posted by toast2266

But even the dirt bike companies didn't know that. Honda threw a shitload of money at the G-Cross program, but as best I can tell, that bike still had pretty typical geo numbers for 2004.

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I think it was a little bit ahead of its time, but you're certainly right that it wasn't close to being up to modern standards. Of course, it's hard to know exactly, it's not like there's a geo chart for those things out in the wild.

My first "head up ass" comment was more harsh than I really meant it to be. Hindsight is 20/20 and when you're used to things being a certain way it can be hard to look past it. But I do think it's interesting to imagine a parallel universe where mountain bikes developed more from stripping down dirt bikes and making them pedal. I get why it didn't actually go like that, but it's fun to think about.

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Originally Posted by HAB

I think it was a little bit ahead of its time, but you're certainly right that it wasn't close to being up to modern standards. Of course, it's hard to know exactly, it's not like there's a geo chart for those things out in the wild.

My first "head up ass" comment was more harsh than I really meant it to be. Hindsight is 20/20 and when you're used to things being a certain way it can be hard to look past it. But I do think it's interesting to imagine a parallel universe where mountain bikes developed more from stripping down dirt bikes and making them pedal. I get why it didn't actually go like that, but it's fun to think about.

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Definitely.

And it is pretty interesting that worthwhile geometry didn't develop earlier. It's easy to blame it on the evolution of mountain bikes from road biking. But there were plenty of guys that had a moto background that were designing bikes fairly early on. Mert Lawwill, Jeff Steber, Doug Bradbury (sort of), etc. - those guys weren't coming at it from a road racing perspective. But even while a guy like Steber was re-imagining DH tires with heavy influence from the motorized world, his DH bike was still running a 66 degree head angle and super short reach / wheelbase numbers. And that was a bike that was at the progressive end of the spectrum.

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Originally Posted by frorider

I am sorta bitter / bemused by all the bullshit bandaids some of us had to use over the years to try to kluge the geo we wanted. Eccentric eyelet reducers, small rear wheel, anglesets,etc. I remember several single pivot bikes like my old Gemini that immediately rode a thousand times better once you drilled a shock mount hole in a slacker location (and slammed seat all the way fwd).

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No way man! That was way better back then because the only people riding mountainbikes were people who gave a shit and really wanted to be there.


Back in my day™ my lawn had fewer people on it!

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Originally Posted by toast2266

To some extent, the speed-ification of trails probably contributed too. It's a lot easier for the average joey to enjoy their 1300mm wheelbase on the latest, greatest flow trail that doesn't have any slow, awkward tech in it.

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I can see this as well to some extent. Granted I grew up riding on the east coast and now live out west but most of the trails we used to ride in VA (mid-90's) were shitty ass old horse trails or torn up moto trails with lots of short, steep techy climbs and no flow for a mtn bike. Many of the bikes today would have been pointless on some of those trails. Well-designed, purpose-built mountain bike trails didn't exist back then.

^ yeah I know that’s the conventional wisdom but my direct experience has worked out differently. I actively seek out chunky old school trails that typically were hiker/equestrian built back in the day. My Modern Geo Trailduro (TM) sled has a 1250 mm WB vs the 1180 WB of a typical so-called Large or XL from 2016. I figured I’d keep my 2016 trailderpo for those tight hiking trails. Turns out nope, the longer sled rips the shit out of those non-flow trails uphill and down. Despite being nearly 3” longer.

Look none of this geo stuff is rocket surgery. And that original 780 mm boobar came out loooong before current carbonz optimized 35 clamp stems existed. Your local bike shop ain’t staffed by Ph.D physicists fer crissakes. One good friend and esteemed bike mechanic told me, in the early disc brake days, that front rotors should be 160 and rear 200 because otherwise you’d endo.

Similarly, there’s no real excuse for Intense bungling basic shock dynamics on the 951 back in the day, or for well funded brands not to use their R&D to build mules with modern geo ten years ago. Maybe it’s because I’m a jaded engineer but compared to the engr problems faced in other industries, much of this bike stuff—-especially the geo aspect—is not that difficult. But brobrah industries can be very conservative.

Mondraker is a brand that is not only well established in yurp but owes its existence to the fact that the major brands just didn’t really use their R&D budgets for actual innovation. Just incremental changes.

And differentiation sells. Sure you can speculate that if Special Ed had released the 2020 enduro in 2010, no one would’ve bought it, but in reality anyone demo’ing it would’ve crushed their local trail and word would get out.

Like rockered skis bruh

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Originally Posted by frorider

I actively seek out chunky old school trails that typically were hiker/equestrian built back in the day.

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That reminds me.

We need to have a serious discussion about tamba one of these days :D

https://youtu.be/JOlc0a2eVTo
I feel like the whole topic is overplayed. Spend a weekend at a bike park or a Pisgah/Moab site and notice the odd guy out doing just fine on an old rig.
Brakes have improved massively. Everything else is just a more refined version of the same old bike. You’re paying a mint for “just a little better”. $1k+ wheelset is the best example.


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Originally Posted by kidwoo

That reminds me.

We need to have a serious discussion about tamba one of these days :D

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Yeah I know what you’ll probably say. And I won’t disagree. ;)

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Originally Posted by frorider

Similarly, there’s no real excuse for Intense bungling basic shock dynamics on the 951

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MY GOD that bike sucked. Thanks for the PTSD flashback.

Let's be honest, there's really no excuse for intense still being a business.

But then you have to remind yourself: "socal"

Because socal.

Intense is definitely giving Yeti a run for title of most Bro-brah

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Originally Posted by evdog

Intense is definitely giving Yeti a run for title of most Bro-brah

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They're pretty much the same brand in my opinion. One sells to the image of hot rod socal, the other to the vermont transplants that bro-ed their way out to colorado to join the mountain tribe. Both with image over quality and both sustaining on that image alone.......with each having pretty legit places in history in the early days. At least there's that.

*beece shuffles off to the corner because he really likes his Tracer 275 and VPP in general, but is now starting to accept that his tastes might run to the old school here and there, and at least he’s now drinking more East Cost IPAs than West Coast IPAs from SoCal, but still maybe he can back off into the corner so no one sees that he has an Intense and 4 more Santa Cruzes in his garage. Awkward. Still, he likes the way they ride...*

beece, time to jump on the anti-bro-brah wagon of elite Bros & Brahs. We fart in your general direction!


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Current intense frames are an entirely different universe these days.

I was more commenting on how they made it up to that point.

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Originally Posted by kidwoo

Current intense frames are an entirely different universe these days.

I was more commenting on how they made it up to that point.

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Do they make anything good now? I completely stopped paying attention like 7 years ago.

Look at some of the leverage curves on some of the current bikes.

I've looked at enough of them to know that they're straight, that's already an improvement. There's something to be said for outsourcing for certain companies.

When you say “look at the leverage curves”, what exactly do you mean? Is there a website with leverage curve graphics? I don’t think most people (myself included) have much more than a vague grasp of the concept.

I stopped considering Intense when I saw multiple catastrophic failures.


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Originally Posted by kidwoo

Look at some of the leverage curves on some of the current bikes.

I've looked at enough of them to know that they're straight, that's already an improvement. There's something to be said for outsourcing for certain companies.

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Attachment 310447

I said bikes, not 29ers.

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Originally Posted by kidwoo

I said bikes, not 29ers.

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They make that bike in a 27.5" too.


I will admit to cherry picking the worst one I found in 20 seconds of searching, but the DH bike is the only one that actually looks good.

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Originally Posted by HAB

Attachment 310447

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I’d love a tutorial on interpreting that. What I see is something comparing Wheel Travel to Millimeters per Millimeter. Struggling to figure out what that has to do with suspension.


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Originally Posted by jm2e

I’d love a tutorial on interpreting that. What I see is something comparing Wheel Travel to Millimeters per Millimeter. Struggling to figure out what that has to do with suspension.


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Short version: It's a graph of how much the rear wheel moves per amount of rear shock compression, across the full travel of a bike. So to use the Primer that kidwoo and I are making fun of as an example, it starts off at ~2.93:1, i.e. 2.93mm of rear wheel movement per mm of shock compression, is digressive for a while up to a peak of about 3:1 around sag, and then drops off to about 2.25:1.

That isn't the worst example of it the bike industry has ever put out, but those kinds of banana curve leverage ratios are pretty common. That digressive bit at the start of the travel kind of sucks because it makes the bike mushy and wallowy around sag (you have a high leverage ratio, i.e. the wheel has a big mechanical advantage over the shock around there).

https://4.bp.blogspot.com/-fqacwccTJ...6_LevRatio.gif

Those are all examples of what a better curve looks like.

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Originally Posted by jm2e

I’d love a tutorial on interpreting that. What I see is something comparing Wheel Travel to Millimeters per Millimeter. Struggling to figure out what that has to do with suspension.


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To add to what HAB said, the goal (theoretically) with the kind of leverage ratio on the Intense is to make the bike supple over small bumps, pedal reasonably well, and not bottom out too easily.

So the beginning of the curve (left side of the graph, 0-40 mm suspension movement) is regressive, meaning the rear axle has more leverage over the shock at 40 mm travel than it does at 0 mm travel. Thus, hitting a bump that moves the suspension through that first 40 mm of travel moves the suspension pretty easily because, as the suspension compresses, it's gaining leverage over the shock.

In the 30 - 60 mm range, the leverage curve inflects. This is roughly the sag point of the suspension, and the curve transitions from getting easier to compress the shock, to getting harder to compress the shock. Putting that inflection right around the suspension's sag point (~30%) will maybe help the bike feel a little snappier on the pedals.

The rest of the curve (50mm - bottom out) is progressive, meaning that the bikes leverage over the shock decreases as the suspension compresses.

If this were a linear suspension with a coil shock, the amount of force to compress the shock is easy to calculate - with, say, a 400lb spring, it takes an extra 400lbs of force to compress the spring for every inch of compression. So that's 400lbs of force for the 1st inch, 800 lbs for the 2nd inch, 1200lbs for the 3rd inch, etc.

That same 400lb spring on this suspension will take additional force, because the leverage ratio isn't linear. So it might take 350 lbs for the first inch (because the leverage ratio is regressive, and then flat-ish), But then 1000 lbs for the 2nd inch (since the latter half of the leverage curve has a falling rate, has less leverage over the shock, and thus takes more force to compress the spring). This is why some bikes work well with coil shocks, and some don't. Air springs are naturally progressive, so they work better with less progressive rates. Coil springs are not progressive (progressive wound springs being an exception), and therefore benefit from a more progressive suspension design.

As far as what's actually good or not, there are pretty clearly personal preferences on that front. The more uniform the leverage curve (like the Geometron curve that HAB posted), the easier it is to tune the shock around the curve, and it generally means the suspension is more predictable. Particularly for anyone riding the bike actively (pumping, jumping, etc.), that can be preferable. But other suspension designs can be made to pedal a bit better while potentially maintaining suppleness / traction at the beginning of their travel, usually at the cost of some support for pumping and popping. And, of course, all of that with any suspension design can be tweaked a bit with a good suspension tune. And all of that can be semi-ruined with a bad suspension tune.

Edit to add: If you want to look at leverage ratios, the graphs for most bikes can be found here: http://linkagedesign.blogspot.com/

I would take most of those graphs with a grain of salt, particularly for short link bikes (VPP designs, DW link designs). But you can at least get a general idea of what different bikes look like. For whatever it's worth, the trend these days heavily favors going towards a simpler leverage ratio curve, similar to the Geometron HAB posted.

That last point on taking these with a grain of salt is a good one, especially for short link bikes (VPP, DW, etc). With those designs, small inaccuracies in selecting pivot points can make a pretty big difference in the result. Single pivots, or longer link 4 bar bikes should generally be more accurate.


And, fine, I guess people can have different preferences from me. :D I pretty strongly prefer more straight progressive leverage curves, but the stuff toast said about the tradeoffs isn't wrong.