Not many people talk about bar height. Perhaps that's because you can't really "sell" a particular bar height in the way that you can market a wheel size, stanchion diameter or fork offset. The thing is, in my view bar height makes a much
bigger difference than any of those things.
In my job I do a lot of back-to-back testing of different bikes, components or setups. But to be honest, in a lot of cases it's splitting hairs. In contrast, even a 5mm change in bar height can have a noticeable effect on how the bike handles, yet this tuning option is often overlooked. And because of the way bikes are designed, I think a lot of people are not running the optimum bar height. Why is bar height important?
The main thing is to keep a good amount of bend in your elbows while in the attack position. You want enough of a bend so that you can push the front wheel down into down-slopes and holes to maintain pressure on the front wheel, but not so much that you have less room to absorb impacts. This arm movement is a bit like sag in suspension - you need enough elbow bend to allow you to extend your arms to maintain grip, but leave enough room to absorb impacts.
If the bar is too low you might find yourself hyper-extending your arms while trying to push the bike away to maintain contact with the ground on steep steps or downslopes. It also makes it harder to look up to see further down the trail, and it's harder to manual too. If the bar is too high, your weight can feel pushed back off the front wheel, or the bar feels too close to your chest. To me the subjective feeling is one of being disconnected from the front wheel and too upright - like riding a Segway. A bar that's too high can also make the bike feel slower to change direction in tightly alternating turns.
So important is bar height that I believe it's been hiding at the heart of the wheel size debate all along. If you go from a 26" bike to a 29er the axle is taller and the fork is longer, which means there's a very good chance the 29er bar is much higher. I think this is a big part of the reason why 29ers were said to create feeling of being "in the bike" and more reluctant to initiate a turn. The reasons usually suggested for this are bottom-bracket drop and gyroscopic stability, neither of which hold much water. I also think that one of the main effects that occurs when changing the geometry of a bike with a flip chip is the difference between the bar height and bottom bracket (the effective stack) increases in the low position. This usually goes unmentioned, but is arguably more important than a 0.5-degree change in head angle. Why saddle-to-bar drop is like sag
If bar height is mentioned at all it's usually measured from the ground to the grips, but this is far from ideal. For a start, it doesn't take into account bottom bracket height, which can vary by as much as 20mm between bikes with similar travel. A better measure is what I'll call the effective stack - the vertical distance from the bottom bracket to the grips. This is just as important as the effective reach - the horizontal
distance from the bottom bracket to the grips.
What really matters is the effective stack in relation to the height of the rider. A good guide for this is to look at the saddle height with the dropper extended to "proper" pedaling height. The saddle height takes BB height into account, and the distance from the BB to saddle is a very good indicator of the rider's leg length, which is strongly correlated with their height.
Road cyclists occasionally talk about saddle-bar drop - the difference in height between the saddle top and the top of the handlebars. Of course this measurement has a direct effect on the ergonomics of the position when riding seated, but it's also a good guide to how the bike will feel when descending with the saddle dropped because it indicates how the effective stack relates to your height.
In these bike check shots, Richie Rude (left) is running a small amount of saddle-bar drop, while Damien Otton (right) looks to be running slightly negative drop (the grips are higher than the saddle). I'd say both are within the normal range for trail/enduro.
After trawling through dozens of bike check photos, it seems like most enduro/trail bikes are set with the grips roughly level with the saddle top when it's at full extension (so zero saddle-bar drop), and personally, this is about where I find my ideal bar height. XC race bikes (as in the diagram above) are sometimes setup with a lot of saddle-bar drop, but the setups of pro XC racers is not necessarily representative of most mountain bikers' needs. This makes handlebar drop a useful benchmark, because for most riders setting the grips level with the saddle could be a good starting point.
Of course this won't work for some riders. For many reasons including limb proportions, flexibility and (perhaps most of all) what you're used to, you may prefer your grips significantly above or below the saddle. But that doesn't stop saddle-bar drop being a useful metric. As an analogy, setting suspension with around 30% sag is usually a good starting point; you may want to go stiffer or softer depending on your riding style or bike setup, but sag precentage is still a useful measure because it takes into account your weight and how much travel you have. Similarly, running your bars level with the saddle is a good reference point because it takes into account your BB height and your leg length/height, but some riders may want to go a bit higher or lower.
Sam Hill's 27.5" Mega from 2017 (left) and 29" Mega from 2019 (right). It's hard to be sure because of the camera angle, but it looks as if both bikes are running a similar amount of saddle-bar drop.Caveats
There are a couple of problems with saddle height as a reference point. Firstly, the effective seat angle affects saddle height, but won't affect your ideal bar height when descending. But for an average BB-to-saddle distance, the difference in saddle height between a 80-degree and a 75-degree effective seat angle is only about 13mm. Secondly, suspension sag. Of course it only matters how your bike handles once you're actually riding it, but if you have a full suspension bike and the suspension is well-balanced, the BB and grips should drop a similar amount under sag when in the attack position. Of course this isn't true when braking, so a higher bar height might be ideal for steep tracks. The relationship between stack and reach
Another factor which might affect your ideal stack height is reach. The distance measured directly from the BB to the grips (in 2D space) is the hypotenuse in a right-angled triangle made up of the effective reach and stack. This distance is known as spread; it dictates how roomy the bike feels.
You might imagine that as reach increases you might want to decrease stack in order to preserve a similar amount of spread. However, I've found the opposite to be the case. A given effective stack on a long-reach bike can make the position feel too stretched-out like Graham Obree
, making it harder to get your weight back, manual and look down the trail. The same stack height on a short-reach bike can feel too upright like Easy Rider
. I find that the more reach a bike has, the higher the bar height I want. So far from preserving the spread, I'm closer to preserving the same angle
between feet and hands, or in other words the same ratio of effective stack and reach. But while reach numbers have got longer in recent years (and that's a good thing), stack hasn't changed as much.
Frame size matters
On the subject of stack and reach, trigonometry tells us that for every 10mm spacer under the stem you'll gain about 9mm in vertical effective stack but lose about 4mm of effective reach because of the slope of the head angle. So if two bikes have the same frame reach on paper but different stack, the one with less stack will have a shorter effective reach once you've added spacers to bring the bars to the same height. This is worth bearing in mind when comparing bikes because those with a low stack height will feel shorter than the reach number alone suggests.
Nobody would put up with an incorrect saddle height, so the seat post insertion is hugely adjustable to suit a wide range of leg lengths. But at best, there's usually only a couple of centimetres of adjustment in the bar height via spacers.
And while the seat tube length varies by a lot between frame sizes, so the range of available saddle height scales with the rider, the stack height often changes very little between frame sizes. You can only make a head tube so short before it becomes weak, and small riders still want 29" wheels and plenty of fork travel. I'm not sure why XL or XXL bikes don't have longer head tubes, though I suspect it has a lot to do with aesthetics or showing a longer reach number on paper. But for whatever reason, the head tube length, and therefore stack height, changes very little between the largest and smallest size.
Courdourier (left) has her bars visibly higher than her saddle, while Connor Hamilton (right) has his much lower. This is typical for riders on either end of the height spectrum.
For example, the new YT Capra 29
has a five-size range going from small to XXL. YT recommends the small to riders around 160cm, and the XXL to riders of 197cm - that's a difference of 23% in rider height. Across that range the reach goes from 427mm to 507mm - a difference of 19% - but the stack goes from 625mm to 652mm - a difference of just 4%. Another way of looking at it is the ratio of stack to reach goes from 1.46 in the small to 1.29 in the XXL. Surely both can't be right. And I'm not picking on YT here; my point is this is entirely typical.
As I said earlier, it's the effective reach and effective stack which matter for ergonomics, but bikes are usually fitted with the same handlebar rise, stem length and number of spacers across the size range. So a lot of short riders probably have their bar height too high, and a lot of tall riders have theirs too low. Changing handlebar rise can compensate in many cases (at 190cm tall I'm fitting a 40mm-rise bar to most bikes I test) but if you're particularly small or tall this may not be enough so you might want to avoid bikes with too much or too little stack, respectively.Conclusion
A friend of mine was scratching his head because he felt more comfortable ripping his 29" hardtail down steep turns than his 27.5" enduro bike. Was it the wheel size, the head angle, the fork offset, or something else that he didn't like about his bigger bike? It turned out the 29er had a much higher bar height relative to the bottom bracket, so I gave him a 40mm rise handlebar for the 27.5" bike and that seemed to cure the problem entirely.
There's no "right" bar height, but just paying attention to this important adjustment is a good start. Nobody would put up with whatever saddle height their bike had out of the box, yet many riders never change the bar height. If the stem spacers don't provide enough adjustment range - and there's a good chance they won't - then a higher-rise or lower-rise bar could be the best upgrade you'll ever make. Measuring the height of the grips relative to the saddle at full pedaling height is a good place to start because it takes into account your BB height and leg length. But remember small differences can be noticeable so it pays to fine-tune with spacers too.