Mountain Bike Geometry 101 | A Complete Guide To Geometry + How It Affects Your MTB

[@Pienimusta]

19 minutes about geometry. Doddy and the team have outdone themselves! Awesome!

[@basengelblik5199]

Was it useful for you?

[@WildMidwest1]

Absolutely useful. Added to my KZbin Favorites short list.

[@wk4max]

Yes!!!! I'm off to buy a new bike tomorrow, so it was .brilliant to receive this important information Beforehand !! THANKS GUYS!!! 😀

[@grahamsmith9788]

I feel so privileged that the Dodster has taken time out of his hair modelling career to explain MTB geometry to us!

[@topspeederalmond]

I really am LAUGHING OUT LOUD

And imagine David Schwimmer is there with him.

[@brianhurley6289]

His hair is as stiff as a porn stars micky.

[@leemilica]

top tube? you probably meant nutcracker.

[@HoxtonLive]

lol

[@Shpektrometer]

Hell yes

[@mikee8244]

@@Shpektrometer and God help those with large undercarriage

[@TheRCNut]

LOL

[@JustMe111094]

I actually saw a bicycle brand called nutcracker and it had that written on the top tube :D

[@cliffsangelsphotography]

Now I need a vid explaining all the different types of suspension linkage and how they behave (VPP, DW, DELTA, etc)

[@Jerry-lc9hh]

Best geometry explain ever!!

[@adkmtb5046]

Absolute hero of an episode. We've all been waiting ever since that ask GMBN ep a few months ago

[@GCarnell]

THANK YOU! Great episode. After a near 25-year hiatus, I started mountain biking again. (Didn’t realize how much I’d missed it. Loving it.) As you can imagine, A LOT has changed; including terms used, varying types of MTBs, components, and more. This episode has provided me with clarity needed.

[@Pienimusta]

How about a video about different suspension linkages. Does the shock placement have any real difference? For example Canyon Neuron 2019, AL vs CF. AL has bottom mounted shock, CF has top tube mounted.

[@RACCHIETTO]

This please!!

[@JerryWDaviscom]

Horst four-point or four-bar rear suspension. Look up Turner bikes.

[@augustlandmesser1520]

Merida/Centurion LRS and GT I-drive also was some interesting cookies. Would be nice to see one retrospective about various soft-tails too.

[@adamotheloanguy]

Yeah that would be really cool. DW Link-Horst-VPP-all the other fun stuff out there. So many cool options these days...

[@jeffpallaya55]

Hi guys how about 26ers frame with 27.5 front fork and 27.5 wheel set?

[@abhishekjmadan]

It's just diamond frame... there's one diamond. There are two triangles though.

[@normadicn5700]

🤣

[@LongPeter]

Yip yip yip yip, uhuh, uhuh.

[@JonPrevost]

If you count the welds as gussets then it could be considered a double blunt ended shallow cut diamond frame. Still, these guys are very entertaining and informative. I wouldn't have looked it up had they not made the mistake :)

[@molybdnum]

OK - I think I figured it out by connecting the dots. You get 5 points on the side view of a "Double Diamond"frame - front and rear hubs, headtube junction, BB, and the seattube-toptube-seatstay junction. The 1st diamond is the one we see clearly in metal - seatstays > toptube >downtube > chainstays. The SECOND diamond in the "double-diamond" construction includes one line that doesn't exist in metal, but is critical to modern geometry. It goes like this: seattube > toptube > FORK LEGS > "missing link". So there's the forward-leaning obvious frame diamond, and a second rear-leaning diamond with a missing bottom line that connects the front hub and BB. What? Ok so - imagine a Penny Farthing. Huge front wheel, tiny back wheel, and no chain - the pedals are mounted directly to the front hub. You can't draw that second diamond because there's only 4 total points. Later than the penny farthing you got bikes with equal wheel sizes, but still pedals directly on the front hub - no double diamond. It was only when someone moved the pedals out with the chain drive that we got the 5th point to connect and the modern bicycle. That invisible bottom line in the 2nd diamond is what makes bikes work the way it does, with stable rear for smooth power application and power disconnected from leading-wheel steering = nimble, controllable turns.

[@michaelholland8693]

Not good when somebody wants to teach us about geometry, but does not know the difference between a triangle and a diamond. :-(

[@vaiosm5818]

17:47 so actually when 29" started it was only 26 existing which usually had around 1.5inch=38mm fork offset. 29 usually had around 2inch=51mm fork offset. so then came 27.5 to split the difference in the middle and it usually had around 1.75inch=44mm fork offset.

[@smokedsalmon3907]

I've been waiting for a comprehensive video like this for so long. Thank you gmbn tech! I love the quick bike anatomy explanation at the beginning. Perfect video to send to friends when they ask about what effects certain measurements have, half the time I never even know myself haha.

[@nqmt9968]

Make a video about fitting the mountain bike for really tall riders. In some countries it's not easy to find frames bigger than 21", which is not enough for guys >2m tall. There's no video like that on YT, so it will be great to hear some tips how to make 21" bike feels comfortable. PS. Another great video. Great job guys 💪

[@JulianIrwinX]

They should provide a range of numbers for each key geometry spec, and describe how those ranges change between riding style (XC, Trail, etc) and frame size (S, M, L, ...).

[@Hangso]

Knowledge is a weapon. GMBN..🙌

[@johnpaulgarcia963]

You have made it so much easier for me to understand the dynamics that go into my bike. Thank you for the great information!

[@Pillokun]

I still prefer to measure the bike by going by the length of the top tube not by the reach. When I am sitting it is supposed to be comfortable and while I am standing I am supposed to be agile and move around.

[@RideAlongside]

Pillokun I agree, but our opinion about geo might be seen as antiquated

[@smalerider1727]

@ Ride Alongside How do you pedal a bike? EET is very much relevant and should be the first measurement considered.

[@philmean5603]

@@smalerider1727 I agree as well. It was a bit of a disservice of him to say ETT isn't really important. I feel it's more important than reach. Especially with these steep seat tube angle bikes, if they don't make the reach absolutely huge by old standards, the bike is way too short. It's all preferences and how you ride, but I ride in the saddle probably 80% of the time. It's hard to argue I should size the bike for only 20% of my ride, but that's the going advice these days...

[@rataflas]

Probably reach is more important for enduro/DH riders where you car about descending and not really on the seat pedaling... I kind of agree about ETT or TT measurement thought... it is probably the first impression if the bike is small or large. Stack is a good one! I never knew I loved a large stack just makes you feel more like in a BMX to me. Shame you are pedal strike prone

[@j4m35doc9]

True, but you can adjust the seated length of the bike with Saddle adjustment, offset seapost and stem length but the standing reach (ie weight distribution between the wheels when standing) is set by the geometry.

[@psyick9543]

I knew all this, but it really made me think about how hard it is to end up with the perfect combination.

[@DubenDeFreshDJ]

Finally a step by step explanation. Most appreciated

[@jayp5823]

I don't know how you make me listen to such a boring subject so intently. You have helped me as a beginner rider with so many of your videos, you and your team. Thank you! I ride a 2015 Diamondback SYNC'R with a 4" bar rise built up an old proflex 96 with a 1x10 as well as a 4"bar rise and I even got the wife out there with me an a 2018 GT aggressor with new hydraulic breaks bar riser pedals upgraded rotors mig shift 1x7 which when I get the money will become a 1x10 and I learned almost all I needed through this channel!! Thanks guys and ride on!

[@juliansjames]

I've been waiting for this video without knowing it! Really helpful to know the anticipated handling changes with changes in geometry.

[@mortonfrankfire5400]

This is truly excellent. I feel like Neo from the matrix when he finally realised there is no spoon!! 🥄

[@nk-dw2hm]

That's true because for half the viewers on this channel there is no bike

[@donsmith2833]

This is the video I needed. I am still riding an old DiamondBack Sorrento from around 2003, old school, so know I have an idea on replacement! Now for frame size for my 6'1" and 33 inch inseam. Note, I have monkey arms, I always need 34/35 arms in dress shirts.

[@rorymcclellan3740]

Not that any of these measurements wouldn't make a difference to different riding disciplines, but how long ago did manufacture start advertising the engineers notes??? Seems like a mind boggling amount of different things to keep track of vs what your realistically thinking of when one would buy a new or used offroad motorcycle. In any case, I always appreciate a rather diligent effort to make info like this digestible. Top notch content!

[@donchristie420]

As a carpenter, that has never got to use that laser level Christmas gift - I finally have a use for it 😬

[@PaulGPixelBike]

Some manufacturers like Trek, sometimes list geometry at 30% sag for full-suspension bikes. That makes sense, because on hardtail head angle steepens when you start pedalling in normal position, and on full-suspension it actually slackens. So why doesn't every manufacturer provide that info?

[@KowalskiVanishing_Point]

Great video. I'm 60 and was riding a Norco Sasquatch back in the early 80s and touring and mountain biking since then. Do I say this to pontificate with my superior knowledge about bike geometry? Not at all! Until this video I have basically been a geometry illiterate and ibnorance has been bliss. I remember putting a suspension fork on a late 90s rigid Cannondale CAAD 600 back in the early 2000s and the LBS guy telling me it would change the bike geometry. I thought "WTF are you jabbering about?!?!" Even with upgrading bikes over the years I just thought this was mumbo jumbo and happily went flying over my handlebars thinking this was expected. Finally, started to clue in it all wasn't just propaganda a couple years ago when I bought a drop bar mountain/adventure bike (Salsa Fargo) that could alternate between fixed fork and suspension with specific specs. This video would have helped me in cobbling together the rudimentary understanding I now have of bike geometry. Any young whippersnappers out there that are poo-pooing this knowledge, listen to the man.

[@carlmildner859]

Just getting back in to cycling.... just found this ENGLISH channel .... FANTASTIC !.... really helpful info. really easy to understand , great presentation THANK YOU ... I just subscribed !

[@gmbntech]

Great to hear Carl!

[@esinduhije1]

You are a good teacher, I have learned more on bike than I have learnt my whole life, thanks you

[@izatsamian4684]

I feel like I'm going to school and doddy is my teacher 😃

[@jrbechthold]

izat samian and it is becoming my favorite class of the day! 😉

[@simonstucki]

super informative and very clearly presented, big thumbs up!

[@4partmedia]

This is the greatest informational mountain biking video ever made.

[@jussiniemi3.07]

Thanks for this video, great and simple explanation about different parts of geometry, there's not that many good vids like this out there so definitely something that was needed.

[@ShadLife]

The thing that bugged me for so many years is how mountain bikes were sized. I grew up riding BMX and still ride BMX. Since the late 80s BMX bikes have always been sized by length, not height. When I started mountain biking in the late 80's I gave up on it right away because the bikes rode so terribly. Short top tubes and long stems. Then I got back into it around 94 or so. I got a Kona and the first thing I did was put rise bars on it and a shorter stem. That bike was the longest top tube I could find in my size. But it wasn't until the early 2000s that I was able to get an On One Inbred in 16" with a 23 inch top tube. I put a 50mm stem on it and loved that bike! But bikes were still measured by seat tube length......all the way through the 2000s. DJ bikes were an exception, but not regular mountain bikes. I just never understood how it could possibly take bicycle companies so long to understand that a bike should be sized by length and not seat tube height. It took a VERY long time to get the road bike mentality out of the mountain bike industry. Those of us who came from a BMX background knew different all along. A full size BMX bike starts a PRO (usually 20.5" top tube), PRO XL (21" top tube) PRO XXL (21.5" top tube) and so on. Due to how high bars are on BMX bikes, 8, 9 or even 10 inches high, the top tube length seems a lot shorter but it's not. Most BMX bikes do measure by actual top tube length and really they should measure by effective top tube length. Since the top tubes are almost always close to the same angle between frames it's not as big of a deal. This is how BMX bikes have been sized for decades.

[@joesuelter1636]

Great video Doddy. Been biking for over 35 years and I can honestly say I learned a couple things. Well done sir

[@computerbob06]

Do you think when Doddy said "If you're the type of person, who likes to Manual a lot".............. He was thinking about Blake?

[@nk-dw2hm]

They usually mention Blake when talking about durability haha

[@davidvestey6014]

Modern, long wheelbase bikes with high up handlebars and short stem make it really difficult to climb hills, it seems to all be about downhill speed now but I find it dull having to push the bike to the top when I can’t get any weight on the front wheel. Bring back long stem, short bar bikes!

[@bensieber657]

GMBN has risen to the top of online MTB publications - just exceptional! Thanks!!

[@jennifertannoch-bland3511]

This is really helpful, thanks. I paused a lot and took notes. About to buy a new bike and the jargon blows my mind.

[@Torpedomtb]

I am old school. I had a Z1 on a GT LTS Carbon and it was slow responding. Almost chopper like. I moved to a hard tail GT Xizang with a much shorter shock which gave me the best ride. It climbed like a goat just a little small for me so I got a custom fit Seven Cycles Sola. and put a Marzoch Marathon on it 2000 era. But it is still with me, it climbs really really well, it went down as good. But the primary ride was about an hour climb then about 2 hour down so the climb comfort up front was important for enjoyment of the ride.

[@jerrycabarloc3728]

I had a Schwinn Homegrown, climbed nicely but was it was nervous on the downhill. Also have a Turner Flux that did'nt climb as well bus was fast on the downhill.

[@dakshsoni]

Really help full video thank you for explaining the confusing nomenclature easily.

[@SyEnsability]

You answered a mystery. Now I know I am not a real mountain biker -- because you said mountain bikers don't sit much, and performance while sitting isn't important. I go down hill much faster than up, and seated pedaling performance is key to me - especially on the big all day rides. I've been doing it wrong for thousands of miles each year. Thanks for clearing that up.

[@rbruce63]

I came to your channel to search for orientation regarding a vintage bike called the Cannondale M800 Beast of the East. The Beast’s frame has a sloping top tube, a high bottom bracket and a very short seat tube. I guess that the next step is actually riding in one. I come from a Cannondale M400 which has a traditional top tube, with minor sloping. Later I purchased a used AMP Research B4 bike and upgraded the rear damper with Risse air and oil unit. But I never evolved to more expensive and modern bikes and long for this M800. Thanks for the clarification of the elements of the bike!

[@richcole3931]

Best geometry analysis I've seen on the web. However, stack is absolutely critical for XC. High bars suck for climbing, especially on 29ers where you're already higher above the ground. It's taken manufacturers too long to figure this out.

[@wordreet]

Nice accurate info my dude!!!!! Yeap, and let me just say that trail angles can change how a bike feels almost more than a frame being a little too long or short. When I raced BMX I had an XL frame, but ran with a fork that had the axle at the bottom centre of the fork tubes, not in front. So I had better stability in the frame with quick steering! Got me a trophy at Bexhill back in the day! 😎

[@meniosg]

Awesome video with important information! Try to do a video for building a new bike from scratch. How to choose the right combination of components according to the measurements of your bike, like crank size, Chainline or the Offset, Suspension travel and Installation height for forks etc. Things that someone has to keep in mind, before buy components and other stuff for his bike. Things that are vital for the stability and geometry. For example when I bought my "unknown" MTB frame from China, it came with the plan of the frame and its measurements. So I had to search a lot on the internet, for information about all the parts of the bike, and then choose the right ones. The thing is that KZbin is full with videos of "how to replace this", "how to maintain that", but not with videos of how to choose the right fork, crankset and other things, especially when you don't have the old component to compare with.

[@petersharkey5510]

I’ve been riding for over 30 years and l’ve learnt so much. Thanks. Brill explanation

[@ghostxfairy]

Thanks. That was awesome. Clear explanations of what the measurements are and how they affect the bike. Was always confused about what exactly offset and trail were.

[@PathLessPedaledTV]

We have an explanation of Low vs. High trail with relation to road and gravel bikes. kzbin.info/www/bejne/gmGupWCZbct6aa8

[@mwong987]

I really like the presenter, very clear and concise

[@piotrka2842]

Very informative. Thx, Doddy!

[@koenhekkelman3644]

you guys should make a video of the different kind of angles and what angles are for different types of mtb

[@Bob_Shy_132]

I always liked geometry discussions. Whether motorcycle or bicycle.

[@QoraxAudio]

3:55 Yeah I have a flexible BB on my bike, it's the square tapered BB that came with it... I can literally see it flexing from side to side when applying force lol

[@flyingclint589]

This is a FANTASTIC video! I learned SO MUCH! thank you for making it!

[@raceface48]

Cleanest shop ever!

[@lukewalker1051]

Brilliant explanation of mtb geometry, the best I've seen. Thank you.

[@dropdbass]

Great video Doddy! Looking forward to the up coming info.

[@paveltarasiq8149]

Trail itself does not mean enything. If You want to know how much stability You get, Coefficient of stability is much more informative. COS = [ Trail / (Wheel base + Trail) ] * 100% under 5% = too scetchy! Consier it dangarous. Close to 5% COS have good designed road bikes ovet 7% = too stable* Actualy it is not stable any more: bike would be good at stright line, but would generaty too much force, trying to lean deeper in coner. I experimented with this, welding front dropouts in different places. After that I found a book about motorcycle geometry calculations. Important note (!): very often COS may vary alot in one bike model with different sizing. Good design tends to have different head angles, to conpensate trail with different reach. COS have more on how safe handling could be, than how fast VS slow handling can feel. Modern "Longer trend" have slacker head angles, more trail and more wheel base, but do not have extreme COS. Consider this when bying some cheaper models, espetialy online -- whey can be engineered not so good, so different size bikes may feel VERY-VERY different.

[@fredoellers]

In times before, industry people try to apply the rules of road bikes to MTBs, and by this way the sport has been remained stuck for many years. As soon as they realized that those concepts don't mix, and mountain bike has nothing much to do with road cycling, the development of bikes and the sport itself have done a great leap forward.

[@RosClan97]

Very informative. Thanks!

[@chrisfontaine6221]

My 2008 Scott Genius has a nice high BB, especially when I threw a 160mm fork on it... I love its ride now

[@mattyfrommacc1554]

Thanks for this, very informative, I have not measured myself up for a bike since the early 90's and things appear to have changed!

[@Christos.Geo.GR1]

Really helpful video. Thing's became clear🎉

[@JoshMcGehee]

Brilliant video. One of the most helpful I've found for mountain bikes.

[@yordyiam]

Great video that takes some of the myths and headaches out of all the number crunching you seem to have to be able to do before committing to a certain size bike. Perfectly explained, great stuff!!

[@laurentpk]

Excellent explanation. Thank you.👍

[@gmbntech]

Glad you liked it!

[@Arfonfree]

Thanks, Doddy, that was the best intro to geometry I've seen. Bookmarked.

[@rupedog]

Clear simple vid doddy, great job. Clear graphics, well done to the doodler with white pen!

[@user-lc2mu9jk2b]

So as head angles get slacker the wheelbase gets larger, which then make the bike longer for handling in switchbacks. Especially when climbing and riding technical stuff. And I agree with the comment that although reach is important, a long virtual top tube may not be comfortable on longer rides. We don’t only do technical riding...

[@augustlandmesser1520]

Extremely detailed video, but in my opinion, still one often neglected but important element is missing which affects not only to comfort, but to stability and (should be) to drive setup: the Q-factor.

[@Ron_Boy]

Bravo! I've long wondered about most of this, and wasn't even aware of some of it. Fascinating stuff. And as others have said, an explanation of differences in suspension design would be most welcome too. Thanks for pulling this together.

[@GreyingNomads]

Really useful video, particularly as I am just about to move from an old 26” bike to something more modern.

[@wordreet]

Nooooooooooo! Hehehe, go 26" fat!!!!!!! That way you get to stay with the old faithful 26ers but experience big tire diameters at the same time. Oh and everybody wants to stop and talk about your spectacular FAT TIRES!!👍 😁😁

[@jrbowens]

smartest guy on gmbn...maybe youtube...maybe the world!

[@gooldii1]

VERY GOOOD!!! Thumps up!

[@BigVanLittleAdventures]

This was a lot better than that guy from nukeproof.

[@thewoodjedi1]

Fantastic , Layman's explanation for what really seems complicated till watching this , although I am going to have to watch this about 20 times to take it all in. 10/10 on this one Dodsters . What I would like to watch now is put a trail bike beside an All mountain or cross country and physically show the difference and why as well as you did in this video. You can skip the gravel bike unless Martyn wants todo it . HaHaHa . I think he's an anti gravel bike guy.

[@mrvwbug4423]

You'll know it the first time you try to do a tech climb if your reach is too long, the front end will come up quite quickly unless you're really leaning on the front (the too long reach effectively takes weight off the front). If your reach is too short, your knees will smack the bars during tight turns.

[@Rubardock]

I waited so long for a video like that! Now i finally understand what it could mean if you talk about some measurements in a bike check...

[@yogeshnaik9276]

I am into stingray chopper models as i feel they are important because for general people such a frame is ideal

[@NVYOUTUBE01]

Superb Video .. Thanks a ton ..

[@basengelblik5199]

If you are taller doesn't necessarily mean you need a longer reach. People with relatively long legs need a smaller frame because their upper body is shorter.

[@rayred74]

Jeez - this video is so long overdue - thanks for doing it. Things make sense now

[@petesmitt]

0:59 Actually, sloping top tubes came about to reduce different frame sizes and instead, utilise long seat posts.

[@joshhunter9299]

Great video and information, Doddy! Of course, I’ll need to watch it a few times to let it sink in. 👌

[@ianmangham4570]

Even going down the street i tend to stand up 🤣 gotta love a mountain bike

[@gerardpolakowski818]

Excellent 101 start video with explanations! Provided new information for my understanding of current designs. Thank You!

[@mikefleissner4415]

Good stuff.like changing wheel sizes.i 26 and 20 and 24...no plans on bigger ..but I know which geometry this life has 20000 on it..im settled in.so I convert to next size wheel

[@Seids_89]

Be great if you could cover which geometry is best for short legs, long torso and vice versa And if certain geometry is better suited to novice and advanced riders

[@ivyoyao2655]

wooow what a incredible bikes....wish i have one in my b.day..

[@ChattanoogaDan]

I am just now getting into mountain biking. Very informational.

[@gmbntech]

Great to hear Daniel :)

[@ericm8811]

Hey Doddy! As you age prepare yourself for the moment that "standard" stems and bars are no longer high enough for your desired riding position! At that point most bike shops and component manufacturers expect you to put a head tube extension or an adjustable stem onto your high end high tech bike! Both of those are heavy, weak, dangerous for off road cycling and freaking ugly! I have chronic back pain and was forced to suffer through really weak low dollar stems and bars until I discovered the trials bike manufacturers! They have quality forged stems and lightweight strong bars made from proper alloy! Hope that the day is a long way off for you! Ride ride ride!

[@walterrosinsky2752]

I have back problems too, I use a handlebars with a 5" rise. Doesn't look ugly and feels great :-)

[@fostelka]

Great work Doddy. Finally I have a bit of an idea what the geometry of a bike is. Thanks.

[@nguyenvanduc2512]

This is the great video. I watched the whole thing but just to understand what the weenies are talking about. Most of the time I don't care about geometry, just choose the right frame size and adjust the rest to my preference.

[@jdub4656]

Doddy great segment. You spoke about muscle useage briefly with the seat angle. I’m thinking there could be a segment on muscle useage, injury, and setting the bike up to compensate or fit a rider carrying a semi-permanent or permanent injury better e.g. lower back, knee or shoulder. Thanks Jezza.

[@botzilla73]

Nice video and very informativ, I´m a XC rider, but is good to know that kind of information!!......I love your show, keep up like this and please include more videos and info about XC bikes and races!!!!.....(I`m a big fan of your show)

[@stevebennett3587]

🤔I bought a 27.5 in a large, i felt a little cramped, had to slide the seat as far back as possible on the rails, and my knees were very near the bars, so i exchanged it for a XL 29er😅now I'm slightly too stretched out, reduced the stem by 10mm, but it slightly pushed my weight back too far, a lesson learned when buying online,🤔a large 29er would've been a better fit.

[@publicmichaelzmit]

Great video! Well explained. Only critique is I wish you would have shown the chain stay length and front center measurements as center BB to center axle as they are measured and not horizontal projection onto the ground. When you do your video on fork trail please remember the potential massive effect the trail can have when leaning the bike and not just riding it straight up.

[@fernandomuguerza7469]

Wow perfect video congrats

[@williammorris7895]

Fantastic video, very helpful. Thank you!

[@highlaN021]

When the people years ago says ''the 29'er are gay'' but today in downhill, xc and specially enduro it's use the same wheels, I would like that at some point they did some review about the Lauf Folks (Trail Racer 29), the folk works nicely and I used it 3 months just to try it in races of xco . Geometry is not essentially brand technology, also of the use that the user wants to give and the purpose for which it is created.

[@99MCougar]

The one thing that gets me is that its still all up to what the rider prefers and what kind of riding he\she does. Geo for rider A can be pefect but horrible for rider B.