# Modern geometry - should I give it a go?



## ChrisEyles (2 Oct 2019)

I've been thinking a lot about MTB geometry and set-up recently having just built up my third MTB. All three of my bikes are set up slightly differently in terms of reach, bar height etc, but they are all relatively old-school in terms of frame geometry, with short-ish top tubes and steep-ish head angles. I've stuck a short stem/wide bar cockpit on one, which worked out well but is a smidge cramped. The other two are stretched out arse-up-head-down jobbies, with the obvious compromises this entails going down hills. 

I've read a lot online about long/low/slack modern bikes being very different to ride. Currently taking this with a large pinch of salt, but sounds like they are supposed to be "better" (or at least more stable) on rough downhills, with possibly some slight compromises on climbing and tight twisty stuff, and a generally different cornering mechanic. 

Would love to give one a go, but all my riding buddies have similar age bikes (late 90s to early 2000s) to me, and I don't know of anywhere local that rents out anything suitable. 

Interested to hear people's thoughts on the benefits - especially curious whether the new geometry tweaks are oriented towards trail centres rather than xc bridleway riding, as I always seem to spend the majority of my rides climbing rather than descending!


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## ChrisEyles (2 Oct 2019)

Oooh... a bit of googling and I've found a place near Bristol that rents out Marin Bobcat Trails next to the trails in Leigh Woods. 

Might have to give one a go if I'm up that way and see what all the fuss is about.


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## SkipdiverJohn (2 Oct 2019)

If your old-school MTB has an arse-up head-down riding stance, then you sound like you should be riding a bigger frame with a taller head tube so you can achieve a sensible handlebar height. 
I wouldn't touch any of those modern MTB's with a bargepole personally. I like my 26" rigids with triple chainrings and no more than 7 speeds on the back. They're simple and all the parts are cheap to replace.


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## Profpointy (2 Oct 2019)

I'm very disappointed in this question. I was hoping for a discsussion of non -Euclidian geometries ans Riemann surfaces at the very least


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## Crackle (2 Oct 2019)

It depends is the answer. Certainly give it a go but there are so many variables, how you ride, where you ride, what you prefer, that you only know from building experience. Certainly my old Marin was of the long low variety, the FF29 I use now is much better suited but in terms of frame angles it's not a million miles away from the Marin but it has longer stays a higher head tube and fitted with 120 forks a 69 head angle. A description of the geometry doesn't always tell you everything though. Here's a picture of the two of them standing together when I was still building the FF29 and the Marin has a raised stem in this picture too.


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## Ming the Merciless (2 Oct 2019)

Profpointy said:


> I'm very disappointed in this question. I was hoping for a discsussion of no -Euclidian geometries ans Riemann surfaces at the very least



I thought we might be talking about riding in five dimensional space time


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## Yellow Saddle (3 Oct 2019)

Here's a nice rule of thumb for you.

If the word "geometry" is used in the context of cycling, whatever preceded the word and whatever follows the word is pure BS. Go for a ride and leave your protractors at home[/QUOTE]


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## Jody (3 Oct 2019)

A low/long/slack bike is not an XC or bridleway bike though so of course they are going to be more orientated towards trail centres. It depends on how much you want to compromise but generally even a slack ish trail bike at 160mm travel will still climb very well. 

They are night and day when comparing them to 90's tech.


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## fossyant (3 Oct 2019)

SkipdiverJohn said:


> If your old-school MTB has an arse-up head-down riding stance, then you sound like you should be riding a bigger frame with a taller head tube so you can achieve a sensible handlebar height.
> I wouldn't touch any of those modern MTB's with a bargepole personally. I like my 26" rigids with triple chainrings and no more than 7 speeds on the back. They're simple and all the parts are cheap to replace.



There is a massive difference. I own a rigid 90's MTB with XT (3 x 7) and a newer trail bike. The newer bikes are far more capable, climb as well too, and are just as quick on XC. They blow old bikes away going downhill, and across really rough terrain.

Give me a modern MTB any day. The 90's bike is for XC only - point it downhill and it's frightening, and it can't stop like my 4 pot trail bike.


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## Jody (3 Oct 2019)

SkipdiverJohn said:


> I wouldn't touch any of those modern MTB's with a bargepole personally.



So you keep telling us.


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## MartinQ (3 Oct 2019)

Profpointy said:


> I'm very disappointed in this question. I was hoping for a discsussion of no -Euclidian geometries ans Riemann surfaces at the very least



So what you got against the 5th postulate?


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## Profpointy (3 Oct 2019)

MartinQ said:


> So what you got against the 5th postulate?



I can take or leave it :-)

It's the axiom of choice I'm a bit doubtful of though


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## Levo-Lon (3 Oct 2019)

Im thinking 120mm traval modern bike will make you smile..

As said long and slack is a bit more DH

Anything 29 wheel now will just be miles better.. Than your 2000 bike.

Skip diver john hasn't a clue as he lives in the 18th century.
Its like saying Barry Sheen's bike is as good as Mark Marques bike.. Just silly


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## Jody (3 Oct 2019)

meta lon said:


> Its like saying Barry Sheen's bike is as good as Mark Marques bike .



We should have a CC day at BPW or FOD and John can bring some of his bikes. Would be great to see how they perform against some of this modern crap.


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## si_c (3 Oct 2019)

Some older bikes are truly terrifying when compared to a modern bike at a trail centre. I've got a mid-2000s MTB which I've upgraded to a 1x drivetrain with modern fork and bars/stem. It's still far less capable that my Wife's new MTB with better geometry and wider, larger tyres.


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## Ming the Merciless (3 Oct 2019)

How bike fare in proper mountain terrain


meta lon said:


> Im thinking 120mm traval modern bike will make you smile..



Has the front travel been reduced in recent times as bikes are now 29r?


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## Crackle (3 Oct 2019)

YukonBoy said:


> Has the front travel been reduced in recent times as bikes are now 29r?


Not really, if anything it's gone up. 100/120 is XC terrain. 20mm of fork height is about 1 degree difference in the head angle. I've a marker on mine and I've never used all the travel available to me doing red type standard trail rides but as Simon says, bigger tyres and wheels also absorb impact. If I was still using the Marin I have as a mtn bike, then the difference is night and day once you get onto gnarlier trails.


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## Ming the Merciless (3 Oct 2019)

But 100/120 was the XC fork length 15 years ago, and even went up to 140mm around 2010. Hence asking what the new geometry is if the fork lengths haven't changed or even reduced from what sounds like a peak.


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## Crackle (3 Oct 2019)

YukonBoy said:


> But 100/120 was the XC fork length 15 years ago, and even went up to 140mm around 2010. Hence asking what the new geometry is if the fork lengths haven't changed or even reduced from what sounds like a peak.


140 XC bikes? i don't recall that, I think they're more trail oriented than XC today. Things like the Ragley Mmmmbop have a 140 fork and 64 head angle. 15 years ago would have been more like 80/100 is my memory or even no suspension. 

A lot of XC racers will ride 29ers with 100mm travel and a low head height and stack for racing. 

When people talk about geometry changes it's not necessarily seat angle or even head angle, though it's more likely to be the latter but also head and stack height, bb height, top tube length to accommodate shorter stems and wider bars, frame clearance for bigger tyres, thru axles, curved stays for stiffer rear ends, those of the kind of things which have changed beyond recognition and transformed bike handling. Likewise, fork length probably hasn't changed that much but thicker stanchions, better air units, thru axles again have all transformed how a bike handles and reacts. Tyres are better in my experience and then there's tubeless which is a whole different ball game. so lots and lots of things which add up.


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## Ming the Merciless (3 Oct 2019)

Yeah but my bike from 2004 has tubeless. Tubeless isn't a new thing for modern mtn bikes. Yes 140mm was seen on XC bikes. Mine has 130mm and that's from 2004. My tyres are 2.1" , just how wide have modern tyres gone now?


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## Crackle (3 Oct 2019)

Yeah, sure, a lot of things aren't new but they've evolved.


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## ChrisEyles (3 Oct 2019)

Jody said:


> A low/long/slack bike is not an XC or bridleway bike though so of course they are going to be more orientated towards trail centres.



That's interesting - what's the main reason for this? Are they a bit less responsive, or is it more a case of being overbiked and deadening the trails?

I probably should have explained the background for my curiosity about this, and why I used the dreaded "geometry" word.

On road rides I switch between a 1960s ten speed (steep head tube angle, arse-up-head-down riding position) and a 1950s roadster (massively slack head angle and sit-up-and-beg riding position). The cornering dynamics on the two bikes feel quite different and I'm really curious if the difference between a modern and retro MTB would be as drastic.

Is the main reason modern MTBs are so much capable the improvements made in brakes/suspension etc or the changes to geometry?

Seems like the only way to answer is to have a go on one.


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## Levo-Lon (3 Oct 2019)

A modern slack DH bike

Check this out, fantastic


https://m.vitalmtb.com/community/Freeridewriter,16915/setup,39497



A modern trail bike also fantastic

https://www.santacruzbicycles.com/e...vitalmtb.com&utm_campaign=tallboy-launch-2020


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## Levo-Lon (3 Oct 2019)

Two links s above for @YukonBoy


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## Drago (3 Oct 2019)

Take it from a professional MTB trainer - it's all in the rider.


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## Levo-Lon (3 Oct 2019)

Drago said:


> Take it from a professional MTB trainer - it's all in the rider.




Very true but a good bike will make the most of a novice..


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## Jody (3 Oct 2019)

ChrisEyles said:


> That's interesting - what's the main reason for this? Are they a bit less responsive, or is it more a case of being overbiked and deadening the trails?
> Is the main reason modern MTBs are so much capable the improvements made in brakes/suspension etc or the changes to geometry?



All of the above. 

A longer bike will be more stable but the longer the bike the harder it is to manhandle round tight technical stuff. 

The slacker fork angle adds stability and reduces the twitchiness of your steering. 

Suspension has changed. Long gone are crap elastomer or spring forks with no or little damping. They can now be tuned for exactly how you want them to feel and react. 

Brakes. We all know how they have changed. One finger on the lever can stand the bike up on its front wheel with almost no effort. 

I think a lot of people can be classed as over biked as such. There are also those who use the heavier hitting bikes to compensate for their lack of technical ability. Sure they can numb the trail. You hit big rocks or roots and the bike stays planted. You can ride over some stuff and barely feel it. 

Its all about what you want out of a ride


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## Drago (3 Oct 2019)

meta lon said:


> Very true but a good bike will make the most of a novice..



A good rider would perform well on any well maintained MTB.

A poor rider won't perform any better on the latest tool.

You either have the fundamental skills, or you don't, and this weeks plastic missile equipped with the very latest in meaningless acronyms won't bestow them unto you.


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## Levo-Lon (4 Oct 2019)

Drago said:


> A good rider would perform well on any well maintained MTB.
> 
> A poor rider won't perform any better on the latest tool.
> 
> You either have the fundamental skills, or you don't, and this weeks plastic missile equipped with the very latest in meaningless acronyms won't bestow them unto you.




Not quite what i said but agree on a compleat novice.

I can relate to my point riding with my son in law.
My skill set is poor in comparison, but a light good bike improves my speed..

My wife is a rider who is terrified of falling off.
So her fabulous levo bike is a waste of money, as she will always struggle.
Plus side is she loves her ebike and this motivation device is worth the expense as she thinks it will keep her upright and gives her the best chance of this. Itis a fabulous bike as i found out at Cannock two weeks ago.
I had the best ride there ever hanging on to it, so on this score i disagree completely with your view.


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## fossyant (4 Oct 2019)

With MTB'ing it's all down to practice and learning. I've got much better since switching to MTB only after breaking my back. Was a steep learning curve. It took a while to tackle certain descent's locally - i.e. at first I'd get off at a rocky section with big drops, but the more you ride, the more you learn, and soon learn to negotiate the obstacles better. Most modern MTB's of a 'reasonable' specification are quite similar.

The suspension travel makes a difference depending upon what you plan to do. Most riders will be perfectly happy with any bike upto 140/150mm travel. More travel lets you hit bigger stuff, but that doesn't guarantee anything. XC bikes used to be mainly hard tails, but that's moved into full suspension as well.

My wife's 100mm FS XC bike is way more than she needs, but it's light, and it allows her to do some off road, that her hybrid can't. My trail bike is a fair bit heavier, but that's partly down to being more burly. If I rode both bikes, back to back, I doubt there would be much difference (other than her's is way too small for me).

Test ride a few, and see how you feel. I just grabbed a bargain when I got mine - I'd already researched it though.


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## BurningLegs (4 Oct 2019)

I had a Peugeot 106 from the 90s. Yes it had drum brakes, no airbags, no central locking, electrical faults, and terrible economy but surely cars haven’t developed that much since? After all, my Peugeot did have brakes and wheels, and it got me where I needed to be..


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## Ming the Merciless (4 Oct 2019)

meta lon said:


> Two links s above for @YukonBoy



Looks like they'd be slow cross country but maybe looks are deceiving.


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## Levo-Lon (6 Oct 2019)

YukonBoy said:


> Looks like they'd be slow cross country but maybe looks are deceiving.




There not CC bikes, ones a down hill and the other is a trail bike.


My 2019 Cross country bike


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## SkipdiverJohn (6 Oct 2019)

The difference is really about speed. No doubt about it, anything with suspension is potentially faster over rough terrain than something where the tyres are the only spring medium. With a fully rigid frame you have to pick your line carefully and be a lot more cautious. You cant just tear about like a nutter and expect the suspension on the bike to keep you out of trouble. A rigid will punish mistakes more readily, and how fast you dare to ride one depends on your tolerance for risk and the amount of surface vibration shock your body is willing to take.
But then, unless you are racing, cycling isn't really about speed anyway. I just like to pootle around whether riding on road or off, so a 26" rigid is perfectly suited to that sort of use and also performs adequately on tarmac. Modern MTB's are too discipline-specific, IMHO, and have lost the ability to also be useful general purpose transport as well as coping with rough surfaces. Back when MTB's first became popular, most riders just had one MTB, and used it for all sorts of riding. They didn't have to have multiple MTB's, because some of them were unsuited to anything but one narrow type of use.


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## BurningLegs (6 Oct 2019)

SkipdiverJohn said:


> Modern MTB's are too discipline-specific, IMHO, and have lost the ability to also be useful general purpose transport as well as coping with rough surfaces.


Almost everyone I see riding in my pan-flat city choose to do so on a modern MTB. I’d say that far more people use them for ‘general purpose transport’ than anything else!


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## ChrisEyles (6 Oct 2019)

@SkipdiverJohn I'd agree with that. I ride the same trails on a rigid properly old-school MTB, an older full sus bike, and a more modern hard tail. The retro full sus is easily fastest, the modern-ish hard tail is easily the least scary on the steep rock stuff, and the rigid is great fun in a terrifying "bouncing off all the rocks oh shoot these vee brakes aren't slowing me down much holy crap I'd better get back on the smooth line fast or I'm gonna die" sort of way. 

Generally I'd say I can ride anything I'd tackle on the modern hardtail on either of the other bikes. I'd be a lot slower and more cautious on the rigid, and really steep stuff would still be sketchy on the full sus (though a dropper post would sort this). 

As you say I'm not a racer, so it's all about having fun at the end of the day. Sometimes I pick the rigid, sometimes the HT or the FS - they're all great fun in quite different ways. I can imagine that a more modern HT might be a lot of fun in a different way again, hence my wanting to try one out and my curiosity in how they compare to older bikes. 

None of them are as practical as my old tourer/commuter bike, but they don't have to be - they're just big boys toys and that's fine with me.


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## rogerzilla (6 Oct 2019)

The old geometry was more elegant and easier to get a decent fit IME. With modern frames you may need the longest seatpost on the market and the shortest stem on the market (I had a 410mm post and a 30mm stem on my Inbred...it looked awful).


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## SkipdiverJohn (6 Oct 2019)

Very few modern bikes are what you could call elegant in appearance, whether MTB, Hybrid or Road. They've nearly all gone down the same ugly route; fat tubes, small frames, absurdly long seatposts.


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## Levo-Lon (7 Oct 2019)

SkipdiverJohn said:


> Very few modern bikes are what you could call elegant in appearance, whether MTB, Hybrid or Road. They've nearly all gone down the same ugly route; fat tubes, small frames, absurdly long seatposts.





You've got to be on something..

Bikes now are bloody stunning creations.
As for an old steel 3 triangle thing, i just wouldt cycle if that was the choice.
I didn't like them years ago and as for 26 wheel.. You really do need to ride a modern bike instead of continually trashing them.

I'll leave you to your rather unfounded belief..


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## Hacienda71 (7 Oct 2019)

I have a 2004 Stumpjumper, a fully rigid 90's bike and I have just bought a 2020 Bossnut which I have ridden at Coed-y-Brenin and Llandegla this weekend. They definitely are different in how they perform. Yes the rider is the most important part of the equation, but put an average Joe on a modern bike or a 20 year old bike and they will notice a difference in capability. The new bike climbs better on technical stuff and feels confident on fast downhills. I don't regret getting the new bike. To the op if you fancy trying one and can afford it go for it.


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## Jody (7 Oct 2019)

SkipdiverJohn said:


> I just like to pootle around whether riding on road or off, so a 26" rigid is perfectly suited to that sort of use and also performs adequately on tarmac.



You can’t compare shopping in an urban setting on a 40lb 90’s rigid to riding a light, capable modern MTB where it is meant to be ridden. Regardless of how you try and dress it up.


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## Crackle (7 Oct 2019)

ChrisEyles said:


> @SkipdiverJohn I'd agree with that. I ride the same trails on a rigid properly old-school MTB, an older full sus bike, and a more modern hard tail. The retro full sus is easily fastest, the modern-ish hard tail is easily the least scary on the steep rock stuff, and the rigid is great fun in a terrifying "bouncing off all the rocks oh shoot these vee brakes aren't slowing me down much holy crap I'd better get back on the smooth line fast or I'm gonna die" sort of way.
> 
> Generally I'd say I can ride anything I'd tackle on the modern hardtail on either of the other bikes. I'd be a lot slower and more cautious on the rigid, and really steep stuff would still be sketchy on the full sus (though a dropper post would sort this).
> 
> ...


Don't tell me you've ridden that bouldery descent from Princetown to Burrator on a rigid!


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## Drago (7 Oct 2019)

SkipdiverJohn said:


> The difference is really about speed. No doubt about it, anything with suspension is potentially faster over rough terrain than something where the tyres are the only spring medium. With a fully rigid frame you have to pick your line carefully and be a lot more cautious. You cant just tear about like a nutter and expect the suspension on the bike to keep you out of trouble. A rigid will punish mistakes more readily, and how fast you dare to ride one depends on your tolerance for risk and the amount of surface vibration shock your body is willing to take.


But when it comes to a climb, particularly a technical one, you're suddenly carrying g extra useless mass, and even the best suspension arrangements waste pedalling g effort.

There is no all round panacea, no one type of mojntain bike that is best at everything. There are times when a decent suspension bike (with a rider suitably skilled to exploit it, which too many aren't) will be quicker, and times when a front squidge or even a rigid will flush its head down the toilet and steal its lunch money. If anyone tells you that one type of mountain bike is better all rou d then you know you're speaking to an idiot.


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## ChrisEyles (7 Oct 2019)

Crackle said:


> Don't tell me you've ridden that bouldery descent from Princetown to Burrator on a rigid!



Hell yes! There's a cracking descent down from Dunkery Beacon (highest point on Exmoor) which is even more punishing on the wrists on a rigid too 

Other than the battering you take on the way down, it doesn't really take that much more riding ability to ride that sort of stuff on a rigid vs HT, as long as you take things a little slower.


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## rogerzilla (7 Oct 2019)

Crackle said:


> Don't tell me you've ridden that bouldery descent from Princetown to Burrator on a rigid!


I have! On an aluminium Cannondale M1000, no less. It hurt.


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