Seat tube angles. A few years ago they were barely worth a mention in a bike review, and now entire paragraphs are being dedicated to a seemingly minor geometry figure. What gives? Are bikes so good now that reviewers are obsessing over details that barely matter? Not exactly. To set the stage, let's go over the changes that have happened over the last decade regarding bike fit.
There was a time when bike sizing was almost solely dictated by seat tube length, similar to how road bikes are measured. You'd figure out what length seat tube allowed you to show just the right amount of post and call it good, maybe going with a longer or shorter stem to fine tune the fit. It was the arrival of dropper posts that really started to shake things up – seat tubes no longer needed to be as long, and riders could easily fit on multiple bike sizes, especially in more recent years as posts with 170 and even 200 millimeters of drop have hit the market.
With seat tube length no longer as relevant, and shorter stems paired with wider handlebars becoming the norm, a new number started appearing in geometry charts: reach. If you draw a vertical line upwards from the bottom bracket, and then measure from that line to the center of a bike's head tube, that's your reach number. It's a way to get an idea of how a bike will feel when you're standing up out of the saddle – your typical descending position.
I've heard people say something along the lines of, “Reach is the only measurement that matters,” but that's not really the case, especially if you're planning on spending any time sitting down while you're out on a ride. Reach is a useful number, but a bike's effective top tube length is still worth paying attention to when trying to figure out what size bike to go with. Due to the range of seat tube angle measurements, it's entirely possible to have two bikes with the exact same reach number, but with very different top tube lengths. That means that while the bikes may feel similar while standing, your seated climbing position could be extra stretched out on one, and almost cramped on the other.
The Whyte S-120 and Pole Machine have the same reach number, but the seat angle gives them very different seated pedaling positions.
For instance, take the Whyte S-120 and the Pole Machine. Yes, one's a trail bike and the other's an enduro monster, but put that fact aside for a moment. A large S-120 has a reach of 480mm, the same as a medium Pole Machine. But when you look at top tube lengths, the Whyte measures 640mm, while the Machine measures 607mm. That's a big difference, one that's immediately noticeable when you're sitting down and grinding up a hill, and it's created by the fact that the Whyte has a 75-degree seat angle versus the Machine's extra-steep 79-degree effective seat angle. There's also the fact the Machine's actual
seat angle is quite steep as well, at 78-degrees.
Before we go too deep down this rabbit hole, it's worth pausing for a minute to go over the difference between actual and effective seat tube angle. Effective seat tube angle is what you'll typically see in a bike's geometry chart, and it's calculated by figuring out the angle of a line running from the center of the bottom bracket to a certain saddle position, typically one that's parallel with a line drawn horizontally from the head tube. Of course, that saddle position isn't going to be the same for all riders, and the effective seat angle is going to get slacker the higher the seat gets, but it's a point of reference, a way to compare apples to apples when looking a multiple bikes' geometry numbers.
Actual seat angle is just that – the angle of the seat tube on the frame. It's useful because it makes it possible to get an idea of how much the seat angle will change as the post is extended. On the aforementioned Pole, the actual seat angle is 78-degrees, which means that the starting vs final angle of the seat doesn't change all that much, while on the Whyte it's much slacker. So why not skip using effective seat angle altogether? Because not all seat tubes start from the same point in relation to the bottom bracket, which means the actual seat tube angle isn't as useful in figuring out what your pedaling position will feel like.
That brings us back to the original question – why is everyone obsessed with seat angles all of a sudden? It's pretty simple, really. Bikes have gotten significantly longer over the last few years, and pedaling around a long, slack bike is much more challenging if you also have a slack seat angle. Slack head angles = good. Slack seat tube angles = not that good. A steeper seat angle puts you in a more centered position for climbing, and it's easier to shift your weight forward and backward as needed, compared to feeling like you're going to loop out any time you start climbing. Of course, you can have too much of a good thing, and really steep seat angles can make a bike's cockpit feel too cramped, even if the reach number seems long. Sliding a seat forward or back on its rails is the obvious solution for fine-tuning a bike's fit, or going with a slightly longer or shorter stem, but there are limits to both of those methods.
It can all seem overwhelming, but it's not worth losing sleep over trying to decide which size bike you should buy. Studying geometry charts and brushing up on the relevant terms will only take you so far - the next step is to attend demo events and test ride whenever possible, ideally trying both sizes if you're not sure which one will be the better fit. In the end it all comes down to personal preference; just remember to make your decision based on what works for you and your riding style, not what someone in a bike shop or on the internet decides is best.
FWIW, I’ve found the 79 sta to be super comfortable and natural feeling.. you’re in a position that makes you want to climb. I let other ppl demo and they said the same. At the end of the day, that Machine climbs well beyond a class of what it should on paper especially considering the weight, HTA and travel.
But without nitpicking (i'm really good at it, sorry), it seems like it's a really good bike, both SB130 and 150.
I have seen that. It works on some droppers
It would be the exact same loading. Force vectors don't care how they came into existence just that they do exist.
That's also not all because other stuff can also be changed but that's another subject.
I've run Command Posts both ways depending on need, there's no front/rear to a dropper.
I used to run my command post like that, worked fine for a long time, still does 7 years in service, many bikes worn out in that time.
My "GUESS" is that the person on this bike being VERY tall, was also too heavy for that spring on that shock and the bike probably sank way too far into it's travel. So the super long stem and backwards post was trying to fight against all that sag...??? BUT, it's just a guess...
I almost bought that bike for the coil set up cause Specialized stopped making the aftermarket proprietary strut for those Enduro models.
Anyway... good, though quick ride today!
Here is a photo of components from a Bontrager seatpost made by the same vendor: www.evanscycles.com/bontrager-single-bolt-rotary-head-seatpost-parts-kit-EV159297
It just uses conical parts that wedge into the seatpost (www.tritoncycles.co.uk/images/bontrager-colour-matched-seat-mast-cap-p19230-87122_image.jpg) and can rotate infinitely.
The owner of the bike you linked must have angled his (or her) seat at such an uncomfortable looking angle by choice, as it does not have to be that way.
The same user has another bike with the seatpost in the intended orientation and the seat appears to be angled upward: www.pinkbike.com/photo/9048998
As an owner of this post, when I released the clamp bolt and nudged the conical pieces to free them, the seat would flop forward or backward into a vertical position. There are no stops.
Maybe the burden of proof is now on the person claiming it's impossible, not the two people who've owned the post in question, one of which has shown you the components of the post that display complete radial symmetry, indicating infinite adjustment range.
As for the descent being the same as the climb, boy you must be a rocket on the climbs or a really, really slow descender. Notice i meant long time-wise and specifically mentioned energy, i didn't mean the distance or path of the two.
Anyway, I''ll concede that the command post could run both ways and the angle wasn't an issue. (gawd knows why the seat angle in my pic is like that then...? OUCH!) Usually I don't believe without seeing. But I'll take your word on it.
You'd think with all the Joplins, Bonty, Spec, and original Maverick droppers, (more?), based on that design that a pic showing that adjustment range or at least a mention in a review would pop up in a search? (google skills fail?) I've seen backwards dropper pics several times over the years, most recently on an Evil Following. But still can't find a pic?
Anyway. I think in the end were on the same side that seat tube angles should be steeper? OR should we start arguing about that too!!!
LOL! ZERO elevation change maybe? Maybe this is proof of the Flat Earth theory that youTube rocket guy was going on about!!!
1. Much of our time in the saddle is spent on steeply angled terrain.
2. Mountain bikes often have a lot of rear suspension that sags considerably when our weight is shifted rearward on climbs.
3. Geometry needs to prioritize the more severe situations a rider encounters. This may compromise geometry for more mundane situations, which is an acceptable trade-off.
1. Our time-averaged effective seat tube angle is not the number stated on a spec sheet.
2. Seat tube geometry should be adjusted to better suit steep climbs; if the seat tube is steeper than ideal for flat ground cruising, that is acceptable collateral damage.
An evolved version of the Redshift Dual Position seatpost may have potential.
Regarding the Redshift, my friend, who has a PhD from kinesiology now, did his bachelor's or masters degree investigating the effects of a moveable seatpost on climbing performance and efficiency. They had a prototype made, but that was the end of it. Dropper posts would have probably killed the thing anyway and it was intended mostly towards the XC crowd (among the MTBers).
Talking about seat tube angles and the pedalling efficiencies the differences cause and then saying 'it doesn't matter going downhill' is... missing the point to put it lightly
As for the reach and ETT, reach is more or less meaningless (which i've said a few times already) since it only tells you a part of the story. 'Normal reach' for a short effective top tube will be horrible due to a short cockpit (Forbidden Druid). Short reach and a long ETT will make the cockpit feel good, but the STA will be slack and the bike will climb badly. I look at the reach number only after looking at the ETT and seat tube angle. To confirm those two things.
EDIT: i went from a 'normalish' reach to an 'insanely long reach'. The bike is much, much better going down. Many people would say it's too long for descending. But it's not.
Don't listen to this. Get a medium.
"[Of course, that saddle position isn't going to be the same for all riders, and the effective seat angle is going to get slacker the higher the seat gets [...]"
I don't see your theory that it is hard to have short chainstays, long travel, and slack seat tube angles.
Look at first gen evil the following, the wreckoning and the insurgent. Short rear ends, and stupid slack seat angles. As a tall guy I couldn't climb much of anything while seated on those bikes as the front would pull off the ground so easily.
That's largely because those of us who prefer a steeper seat tube angle haven't had any options. Now we do and we're ecstatic.
I agree with you that the problem largely came from maintaining traditional 73° seat tube angles as bikes gained rear travel, which inherently squats on climbs.
Perhaps the answer lies back in 1995 with one of the first remote adjustable seatposts.
The power post extreme had a climb setting which sat the rider forward at the push of a button.
What is old is new again.
Guess it depends where you live. I can't really think of a trail near me that I would ride a long-tavel bike on that doesn't have at least a 1/2 hour climb where a steep seat angle helps a ton. We don't have many green climb trails here like some other areas have, so you gotta ride up to get to the descent. I'd say 80% of my pedal time is spent grinding up steep ass grades. There are certainly flatter, tamer trails with less steep climbing, but they also have less descending, so no reason for a long-travel bike on those.
ALSO, there are lots of set back dropper posts out there, so it's easy for someone to size down and use a set back "if" for some reason they spend most of their time riding on flat terrain...??? (bummer)
Reach measurements may need to increase well beyond where they are now, which will probably mean steeper head tube angles and longer chainstays to maintain a manageable weight distribution.
Bike designers have surprisingly little time to test each revision of a bike, which rarely leaves enough time to test every possible variable. We often see changes made in a stepwise manner and some consequences of prior changes have to be addressed in the next model update. It's the unavoidable trade-off between R&D thoroughness and bringing the product to market quickly enough to not go bankrupt!
I understand this new philosophy as simply being maintaining KOPS but at certain grade rather than flat, but is there any new consensus on how bike fits should be carried out to take advantage of this. Like doing a bike fit at a 3% angle or something? If we're not changing bike fits, than steeper seat tube angle doesn't really change anything.
Also my conspiracy theorist is we have all these steep seat tube angles cause thats what you have to have to package a long travel 29er with 2.6" high volume tires with reasonable chain stay lengths. Putting you more fwd in the seated position is just the by product of the packaging constraints. My sentinel has zero clearance at bottom out, they had no choice other than a steep seat tube.
Now, that’s just one of the articles he wrote on it and it is focused on sliding the seat back to balance for a low stretched out aero position on a road bike, but the inverse is also true. You raise the front and shorten the stem for better bike handling and more fork travel into a more upright position, the seat must come forward to maintain balance.
I think what we are now seeing with SAs is just a realization of the fit principles Hogg wrote about years ago, just flipped for current long travel mountain bikes.
Imagine, for example, that you kept your saddle and bar in their current positions, but your BB was moved somewhere ridiculous, like the bottom of your head tube. There would be a lot of strain on your lower back and hamstrings as they stretch just to reach the pedals, let alone apply power. You can see how the relative positions of your hips and feet could lead to stress and injury.
It was by coincidence that, in a particular era of road riding, the typical position of riders produced lowest stress on the knee when their knees were roughly over the pedal spindle at the horizontal forward position. Unfortunately, this coincidence was misinterpreted as a causal relationship.
The other trend that I think goes with steep SA is the more rearward cleat position or flats that many people on longer travel bikes prefer, effectively shifting the steep SA closer to KOPS.
On the other end of the spectrum on a road bike with a slammed 130-140 stem, many pros ride with a seat slammed fairly back and it climbs fine, but are comfortable in the drops for hours. Phinney has this setup.
What is providing the additional stress into the knee.
Moving forward on the bike changes levels of force on other parts of your body like your back and arms. It also changes your hip angle. If you make this one change but left every other part of your bike for the same you will likely have some problems, but not with your knees.
Similarly, a very open hip position (hips forward, relative to BB) can reduce recruitment of the hamstrings and glutes, putting more demand on the quads. Patellar tendon issues are the common result.
I got really into Hogg’s fit technique and what he was saying years later which blew out all the old formulas. For awhile after that, I was helping fit my teammates or friends loosely based on our understanding of his theories. Most people were set up with KOPS and then we worked from there for the changes, sometimes not much change but others were pretty significant. I think just about everyone was happier and ended up with far less hand numbing or back pain, and after about 30-60 days with the new fit, most showed more power. My changes let me complete a couple Hundos on the mtb and some really long days backpacking without hand or back pain, something I always suffered with the old fit charts.
I remember reading Lemond’s description about Italians back in the day setting cleat position, pretty much slammed the cleats all the way back and called it good. Funny how we are almost back to that.
Similarly, a mountain biking friend of mine paid a triathlon shop over $200 for a fitting that mostly considered his hip angle; with a mountain bike height front end, they sourced a seatpost with several inches of layback to give him a triathlete's hip angle.
I'm not saying all fit formulae are nonsense built from coincidental relationships that only work for people in the middle of the bell curve ... just most of them!
Its true though, on the flats its not as comfortable. When pulling my kids around in the trailer on neighborhood streets, or when some of my trails require riding on a road for a bit there is more weight on my hands than I would like. HOWEVER, most of my trails (the fun ones anyways) are winch up and drop down. Steep STA shine the best in this type of terrain.
Finally, XC bikes don't need steep STA because they don't sag 3 inches into their travel and spend more time on flats.
Pro Road cyclists as well. This is because if you are quite fit and riding on more mild terrain, KOPS is a good place to start.
For most of us that is not our reality and so KOPS is just a funny thing that helped people sound more educated when trying to sell road bikes.
Yes, pro road and mountain riders mostly use similar positions, but not all. Adam Hansen uses almost a TT position on his road bike, a few riders still slam the seat rearward on offset seatposts, female XC riders often ride super far forward, Jaroslav Kulhavý rides that wacky seat angle ... there's enough variance even within the pro community - never mind the amateur community with our dysfunctional body shapes - that KOPS provides no actionable insight.
As I mentioned before, the best counterexample to KOPS is that recumbent bikes exist and don't inherently cause physiological problems.
Also if you look at a lot of the xc riders who have a "slammed" position when they are on the bike the saddle to bar drop isn't as big as it looks, they are just tiny guys on 29ers with tall front ends.
Another component of fit should be size and model selection. There was less choice when it was a current model, but just looking at the Spark in your profile hurts me. Nowadays a Ryve could be more ethically suggested. It's no wonder there's confusion on Transition as despite the marketing of SBG, their STAs aren't all that slack. Long inseam folks are likely to size down in order to get toptube to fit. 'Get a medium,' as advised above, is popular advice here.
The world champion XC rider on his bike...that is very much what I would call a "Lance fit". Nothing extreme.
But I’d hardly call that the fit I want to emulate for a trail bike for me. I spent too much time on a slammed position on a road bike and now like a decently upright position.
When some of us say climb like an xc bike, it’s basically referring back to when you had to fight to keep the front wheel tracking even on a 140mm bike and it straight up sucked. Instead we had Talas forks so we could drop the travel, effectively giving a steeper SA for the climb, but it would suck if you forgot to flip it back. So when you can ride a 160 travel 29er, don’t have to change the travel, and barely have to weight the bars to climb a steep pitch and keep the front end down, like an xc bike, that’s what we mean. Not that it’s as efficient, light, or as fast as an xc bike, but not struggling like a trail bike. I have no trouble riding my 76SA 160mm bike in 6,000 vert days. I wouldn’t have said that just a few years ago with the older geometry.
Steep seat tube angles are here because of the squat. That 75° seat tube angle that is marketed turns out to an actual angle of closer to 70° (relative to the ground) once you sit on the bike and then start climbing.
Plus, short chainstays and big wheels and tyres are the reason for bent/offset seat tubes, not the reason for steep angles. Steep angles actually enable short chainstays because you move forwards with it and are not impacted by the short rear as much as you would be on a slacker bike.
I'm kind of thinking smaller riders could actually maybe use a slacker seat tube angle (when the rear wheel would fit under the seat and everything).
Yes, plenty of xc pros are close in fit, but Nino being on the far end of the crouched spectrum these days.
No, I can’t keep up with Cat 2 these days. At least not on the climbs: I’ve gotten too big in the gym for my firefighting job, and my diet is not as disciplined as it once was. But over 50 Cat 2s are a lot of my riding partners, so are some former Cat 1s. I’ve spent plenty of time in Lycra with a number plate on my bars or on my back between 1990-2013 in xc, road, and cx. Never liked road racing much though. I gave up on racing in 2014 when training to break 9hrs on a hundo with 14k of vert in Colorado when I dislocated my shoulder (missed the 9hr mark the year before by 30 min from dehydration).
But my experience has no relevance to my point that steep SAs are the shit for making long travel bikes climb worthy and my Ripmo is the bike I grab for long days of up and down. I have to move up on the saddle nose less on my Ripmo than I do my Scalpel on steep climbs, it really does climb that well, and combined with the long reach I am not too upright or cramped, just have to get used to a long wheelbase. The Minons I have on the big bike slow it down more than the travel or angles on the climbs.
On any bike that you pedal seated fit is THE MOST important part. Descending doesn't matter. It takes you an hour of pedalling on flats and up the hill to do 15 minutes of descending. The energy and time consumption ratio simply makes pedalling fit the absolute priority.
Reach is useful for park and DH bikes and the pumptrack, DJ, etc. bikes. Enduro bikes do not fit here, neither do trail, XC, etc. bikes.
And this article beautifully shows why and how reach is a useless number. I increased the reach of my bike by 6 cm, but the cockpit lengthened only by 3 cm. And the overall fit of the bike increased dramatically through a steeper seat tube angle.
The descending performance? The wheelbase is 7,5 cm longer, it's a 29er and many said it's too long. It goes down the hill like an insane badger compared to the previous bike. I'm riding on a whole new level and it was a night/day change from the old one. Granted, a large factor of it is a 170 mm dropper compared to the 125 mm of the old, but still, the grip, composure and stability this bike has is insane. And it has an 'insanely long reach number' (522 mm in XL). Yet, again, it _WORKS_.
Instead of thinking of the FC:RC ratio, think of the ratio of wheelbase behind the centre of mass to wheelbase ahead of the centre of mass. That becomes a dynamic ratio when sag and ground slope aren't constant, and it's the relevant ratio.
This is your short chainstays, long front sucks situation, which i say is wrong. It's the centre of mass position that's important and that has NOTHING to do with chainstay/front centre length. At least not directly.
Your statement completely depends on where you ride. The only time I have felt awkward on a steep seat angle bike is while pedaling the mile or two to my local trails, on paved and gravel roads. Now I have not been on any of the extreme seat angle bikes but once on the trail having the steep SA for the silly steep grinds up is great. Then having that long reach so that my 6'4" self isn't having to do the tiniest adjustments to change the weight on the front v the rear wheel has felt great. It is as if bikes fit me for the first time since I started riding mountain bikes 29 years ago.
You can find an XC hardtail with more than 440 mm of chainstays, but then i will find an enduro bike with an even longer chainstay. It's simple, hardtails don't have suspension and can have shorter chainstays, if needed.
Of course they have shorter fornt centres, since they don't have as steep seat tube angles, the reach doesn't need to be as big. And since they don't have the head tube angles as slack and forks as long, the front axle is much closer to the BB. Therefore shorter front centre.
And, like said many times here, where is the magical KOPS on a recumbent bike?
XC bikes climb well... Period. Not due to KOPS.
I have a scale RC, but the front center isn't long because of the seat tube angle, it's because you don't want the front end pushed out on climbs. The scale still is long and slack for an XC bike, in order to run the cockpit on my old hardtail I have now I would need a 100mm stem instead of an 80mm, and it has a 68* hta. It doesn't climb as well as the old bike though...
As for the pros and knees over spindle... Everybody riding a bike pedals, surely you can't move around on a bike without pedalling!!! *Cue chainless downhill races*
Please, please try and use your head, what would happen if you would rotate the biker, seat, BB and handlebars by 90°? Where is your KOPS now? What about in space? They pedal bikes there. In space it can be PSOK!!!
How many times must it be said that KOPS is a happy coincidence and that there is simply no logic in it having any merit? Why would you have to have your knee over the spindle? How will you have your knee over the spindle on a recumbent? On a cruiser? What if you laid on your belly and had the pedals behind you?
Please tell me why would the knee have to be exactly over the spindle? What is the magical force, field or any physical property that requires that??
A person's position on the bike is optimized by balancing the forces on the contact points for the terrain that they most often ride.
The force of gravity on someone's leg helping them pedal is not a consideration.
Plus, the heavier the foot, the more it presses onto the pedal when it's moving upwards. So it cancels itself out. So your efficiency is... none.
Maybe I was just feeling good those days...but as far as climbing feel goes, steep seat angle > DW/VPP/ect.
Now I have both DW-Link and steep seat angle on my Ripmo
(The suspension kinematics are another matter, of course.)
Especially considering chainstays all being the same length on all the sizes is a remenent of steel manufacturers only making one or two sizes of chainstays and you are going to be drafting right so let's tuck those wheels under you as tight as possible.
Plus, any differences in chainstay length need to be an actual difference, not what Norco has done (move the BB shell forwards on larger sizes, making the STA even slacker - counter productive to the MAX).
Pedaling the steep angle bike on NOT steep terrain feels wrong, I'm way over the cranks, and can't move the butt back any further, I had to dig out a setback dropper post, which puts me 25mm back to where I'm used to being. I have yet to get a ride in and see how it feels. The industry needs to update the charts and give us ETT at multiple heights, this will clear up the confusion.
Literally all geo charts have ETT (effective top tube) measurement. That's how..
Guys it’s pretty clear when you ride it, the Pole just climbs better. Everywhere. Tech or not. Even though it’s heavy and long, it’s the #1 pleasant surprise for me about the bike is just how damn well it climbs. The body position is just that much better, and it shows... wouldn’t have believed it until I tried it.
Steeps eat tube angle does move weight off the rear, as in not all of it is there. Which is a clear bonus. It's not that there is too little of it, it's that there was too much weight on the rear before.
But it's hard to argue against modern geometry. My current bike isn't extreme by any means (Transition Smuggler) but it's squarely in the upright seat angle, long, slow, and slack territory for a 29er with 120mm of rear travel. The damn thing rips down and the climbing position is so comfortable compared to my previous bikes with ~73 degree angles.
I won't go into the whole reduced offset fork thing, but I'm a believer and have been since testing both the Ripmo and the Smuggler at Outerbike.
It's probably the most important question here.
Steep SA is good for some things, power efficency is not one of them.
I find all of mountain biking to be about the equipment or get fast tricks n tips. Nobody wants to hear that the latest n greatest isn't needed and that their technique sucks and everything they thought they knew was wrong.
In my opinion, mtb went down hill when all the engineering geeks with expensive degrees thought it would be cool to work in mtb industry and try and make real money turning a grassroot hobby more mainstream. All about the money now they have to constantly keep sales increasing exponentially. So the machine works hard to keep people thinking they need more and new and go faster, spend, spend, spend.
My understanding is that 30% rear suspension sag is not necessarily 30% rear suspension travel since the leverage ratio changes through the shock stroke. In the front 30% sag is 30% travel. As a result, a 150mm/150mm bike set @ 30% sag front and rear is no longer level like it was when it was sitting there and the angles were measured. Would get even more wonky on bikes with different travels F/R or different sags F/R.
Would it make more sense to give angles at prescribed sag values?
The problem would be in agreeing on the sag at which to take these measurements. Even if an industry that can't agree on the saddle height for effective seat tube angle could agree on these sag numbers, what do we do for a highly progressive rear linkage that benefits from more sag or a linear suspension that should be run with less?
I agree with you in principle, but I don't think it can be implemented.
What tire size is used for BB heights? When measuring reach, at what stack height is the reach taken (stack and reach are not independent and reach should be measured at a standardized stack). What fork offset is used when measuring wheelbase? How is the effective seat tube angle "effective" when no one actually sits at the height at which it's measured? When companies quote kinematics numbers, like anti-squat, what gear combination, centre of mass height, or point in the travel is being referenced - these things can double or even triple the value! When measuring standover clearance, is it measured at the lowest point or at some arbitrary point along the top tube?
None of these things are standardized, so there's no hope of standardizing the sag at which a seat tube angle is measured - even if there was, at what height would we measure the seatpost extension? And would that height change for each size? What if a bike fits uncommonly long or short, relative to the nominal size, and most riders size down or size up on that model - should we try to incorporate that?
Speaking of which, there is a bike for which the size Small has a reach approximately equal to the median reach for size XL frames - and its front-centre length is in the top 25% of XL frames! Anyone who shops for bikes based on a familiar nominal size could be in for quite the lesson on standardization.
Now that I'm at home and can look at the database, the G16 has a front-centre of 833 mm and the Machine 160 is 830 in their versions of size Small. That's longer than 80% of XL frames in the past six years.
Pushed my seat waaay back, threw on a 60mm stem and boom- now it felt natural and fast when seated.
Another quirk of steep seat angles: dropper length is even more important. With the seat being so central on the bike when you stand up you're above the seat, but it's no longer behind you (like it would be on a bike with a slack ST angle.) Which basically means you're using the dropper more than (at least I was) used to in moderate terrain just to have the seat out of the way a reasonable amount.
No offense, just a question based on curiosity.
it's a quirk of the steep angles for sure, but since I've been riding it a bit more I've crept the seat farther forward cause it makes climbing steeps so much nicer. still sticking with the 60mm stem though.
I'm 5'9" and nearly exactly 5'9" wingspan.
This is another case of how useless the reach number is, while it's really insanely high on Poles, the cockpits (effective top tube length) lengths are not so extreme. Couple that with an insanely steep seat tube angle (which comes into play a lot more in XL size than at your height, that is true), and you get a lot less of the lengthening effect by raising the seat.
Here's a shocker: Poles are short. The cockpit is short. My 522/680 mm length and 71°degree actual angle Bird AM9 XL does in no way feel long, i have zero outstreched feelings on it. I'm afraid i would have to move the seat back and use a longer stem on a Pole just like you had to.
I have come to terms with this after looking at geometry charts after i made that original comment. And the story is very similar with the RAAW Madonna, which also appears to be a really long bike, but isn't necessarily so once you get into the nitty gritty of it.
Maybe I am mistaken but I don't see Pole having BB in a different position than Whyte, while seat (angle) is slammed forward for better pedaling, but is it really better? Because, in a world where machines are pedalfriendly enough for this type of riding they are intended for, I'd rather save knees.
Of course there are downsides. The huge setback requires a larger diameter seatpost (or dropper seatpost stanchion) which in turn requires a larger diameter seattube to keep up. Plus of course there needs to be enough room for the rear suspension (shock, linkage, wheel travel etc). It is a bit of a chicken-egg dilemma and I expect a company like Specialized or Liteville that does both dropper seatposts and frames have the edge here as they can develop them as a system. Though of course it probably doesn't take much for a company like Cannondale to do that too. That would be the first square seatpost with roller bearings.
Either way, it may take a few years but eventually things are going to happen exactly the way I told you here.
Now, who wants to borrow this crystal ball next?
That and the saddle interfering with out-of-the-saddle pedaling, if not dropped, is annoying. That all said, it feels great on climbs and I got so used to it after a month that I greatly prefer it. That and I think it helps train the same muscles I use for out-of-the-saddle pedaling. Makes me feel like bikes still have slack STA primarily since people want to transfer their seated road bike training over to the dirt.
I know, since I got a near 90d effective STA on my bike: www.pinkbike.com/photo/17190421
I switched back to a 27.5 Jekyll Med, from my experimental bike, for a ride today and it literally was 15% slower on the road, and harder on my knees on the dirt. Nice thing was that its 420 CS and 1190 WB made its handling out-of-the saddle impeccable, for doing freeride and slopestyle stuff, and had great grip for hammering out-of-the-saddle up steep climbs as a bonus. The shitty part was that the fork/shock sag varied so much, between my seated to standing position.
Makes me wonder how the Jekyll would be with a steeper STA, much longer reach, and steeper HA, but the same CS and maybe a very slightly shorter WB, would handle. Swap out the front with a 29er too. Would get the front end higher to counter the steep STA, and there'd be less weight distro variation between seated and standing. I'm sold on the smoother ride quality of steel though...
Why is this is still a subject. It was all drilled 1000 times. Suuuper long bike are for pros that need speed and for cripples that need stability. For everybody else we have normal bikes. Now. For those super long bikes you NEED super steep seat angles because otherwise they are unrideable (like this whole Pole shenanigans). So there you have it. You're normal bike park rat: 75-76 for you. You're super duper fast or you're super duper weekend woriorish: straight angle and up goes for you .
On a TRAIL you need a better pedalling position, so a little back saddle is good... That's where the Commemcal is better than the Pole.
Perfect for me? A little bit longer saddle, and forwarded, where can I keep traction on climbs and good pedalling on roads to the trails... That is not a problem of angles.
I've ran my own bike with eSTA of 75, 75.6 & 76 degrees (measured at actual seat height changed by using anglesets, seat position, and stems) and I feel a bit stronger at 75.6 degrees and I do lots of steep climbing.
I just purchased a new bike for my wife and she climbs less steep things than I do and as a result I purposely choose to stay in that 75 degree range. However I wouldn't put myself or her on a 72-73 eSTA ever again and in fact that and other desired geo changes are what led me to get her a new bike. The silly short reach and ETT dimensions on bikes from just a couple of years ago is actually a MUCH bigger issue than the STA.
And a forward offset dropper post would only work if your old bike, was 2 sizes too large for you. And then the seat tube length is problematic.
Let's say we always use 33% rear sag and 20% front. Imagine, for example, a bike with 1 mm of front and rear travel. If the rear sag goes to 50% and the front to 10%, essentially nothing changes with climbing. Now imagine the same change with 1 m of travel: that bike may have just flipped you over the back!
EDIT: what i'm trying to show that sizing up and slamming the seat forwards, while it does work, is not the best solution to the problem. It's the industry's job to take care of that.
Engineer: here is the new Bike, the seat tube angle has been optimised for performance, efficiency & comfort
Sales: yeah but guys, the consumer won't buy a bike with wonky angles
Marketing: Dude we can market a bike that looks like that
Engineer: ok you win here is the bike with chopper angles
Tip of the saddle shall sit 5 cm or more behind the bracket unless there is a morphological exemption.
I think this is the point that everything started from. It is not a secret that if you decrease setback you use more the quads at the stroke and if you increase it you use more hamstrings-gluteus. This is the reason why triathlon bikes are set up different from TT bikes. In triathlon they want to protect quads for running so the use more setback generally.
In a bike world that everything started from road bike geometry it makes sense that seat angles were around 73°. They use this form the point of efficient power transfer and equal muscle fatigue probable. Of course if you don't road,cx,xc or marathon race no one can force you to adapt that. EWS is not UCI and enduro/trailbikes should adapt their geometry to give the best. It was about time to make this step as it seems.
Effective Reach = Distance from center of seat to center of head tube*
*assuming seat it level to top of head tube
Essentially the red line Kaz drew from the seat to the head tube you see in their picture. Which is not reach as that line would be shorter since it start from the point where a vertical line from the BB intersects the horizontal line at the top of the head tube.
The only catch is that it is seat height dependant and is hard to do for all people. Unless you had a 'calculator' on the bike's page that was interactive.
Sizing up on the Reign was hard to do due to the long seat tube.
does actual seat angle really mean anything? it seems to me that your position relative to the bb (which i presume makes or breaks a bike's feel and fit) is determined by effective seat angle.
Have a go here: docs.google.com/spreadsheets/d/10axDne-F31AshWyhrgYH5qVU6ytt3D32FHRGwCh4Oe4/edit?usp=sharing
Nailed it, Kazimer.
Too short to be a Pinkbike write up, but henceforth, this shall be The Bible of ST Angles, and it's all you need:
130 mm or less: 75 degrees
140 mm-ish: 76 degrees
150+: 77 degrees
The shall be no decimal point degree values accepted.
Becasuse bike industry want's you to change your bike again.
Lee McCormack (Lee Likes Bikes) had an article about bike geometry on Pinkbike several months ago (RAD/RAAD, etc.) and there was going to be a followup. I must have missed it.....or it never happened.
Regardless, he even gets into the rise/sweep of the bars relative to the fork stem location and how that affects handling.
I'd have to say that most MTB'ers should be realistic about the type riding they do and get a bike set up for that. If you spend most of your time in the saddle, a close-to-road road setup is probably best. If you spend equal amounts of time going up and downhill, get a dropper post. If you spend most of your time going downhill.....who cares where the saddle/STA angle is when the dropper post is bottomed out?
Philosophy: All the bikes are so good today....it's the rider who is the limiter. We're counting the angels (NOT ANGLES!!) on a pinhead (fork offset, STA, bottom bracket height, etc.) instead of using the "big axe" most of us demonstrate in our everyday MTB'ing.
Even if I used the same bike Sam Hill rides set up for me, I'd still never even complete the courses he rides without walking. Same for Emily Batty and Jolanda Neff et al.
And if most of us spent the same amount of time practicing basic MTB skills as we do reading and contributing to these so-called enlightened discussions, we'd be way better MTB'ers. ME TOO!!
Ride what ya brung ....get better skills.......and ENJOY IT!!!!!!
1. Stop thinking about the geometry of your bike. Don't educate yourselves, don't think, just ride. And, presumably, buy your next bike based on colour, because they're all the same.
2. There is no point in trying to ride better equipment because we're not the best riders in the world. We should ride bikes that match our level, which is very low, so maybe most of us should ride department store bikes.
Although it's true everyone would benefit from improving their skill and fitness, that doesn't mean we can't also improve our equipment; these things aren't mutually exclusive.
I went from an actual seat tube angle value of 72° to 75°, 27,5" to 29", +6 cm on reach, +7,5 cm on wheelbase and from 125 mm to 170 mm dropper. My riding has improved to another level because of the bike. Quite a lot because of the dropper (i have space to move going down) but the length gives a lot of stability to the bike and the climbing improved due to the seat tube angle. And i pop a lot more stuff than i did before.
The bike made a big difference for me. Saying a bike doesn't make a difference is like saying Sam Hill should be just as fast in Val di Sole on an XC bike as he was on a DH bike.