There\u2019s plenty to consider if changing or upgrading your stem, from its length and angle to the material a stem is made from and compatibility with your handlebar and steerer tube.<\/p>\n
With that in mind, here\u2019s everything you need to know about bike stems. You can also use the links below to jump to the relevant section.<\/p>\n
- What is a bike stem?<\/a><\/li>\n
- Stem length, rise and diameter<\/a><\/li>\n
- How to measure stem length<\/a><\/li>\n
- Adjusting a bike stem<\/a><\/li>\n
- Stem material<\/a><\/li>\n
- Road vs MTB vs gravel stems<\/a><\/li>\n
- Bike stem standards<\/a><\/li>\n<\/ul>
What is a bike stem?<\/h2>\n
![\""Zipp\"]( "\\"\"Zipp\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Zipp\u2019s Service Course stem.<\/span><\/figcaption> Stan Portus \/ Our Media<\/i><\/span><\/div>\n On a basic level, the stem has a simple job: to connect your handlebar with the fork steerer tube and, with it, the rest of the bike.<\/p>\n
At one end (nearest to the rider if sitting on the bike), the stem has a hole through it top to bottom, with pinch bolts to clamp it to your bike\u2019s steerer tube. Here, the stem holds the steerer tube in place in the headset<\/a>.<\/p>\n
At the other end of the stem, there\u2019s usually a faceplate connected with four bolts, two at the top and two at the bottom, to hold your handlebar in place.<\/p>\n
![\""Norco\"]( "\\"\"Norco\\"")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>The faceplate holds the bars in place.<\/span><\/figcaption> Ian Linton \/ Immediate Media<\/i><\/span><\/div>\n Between the stem faceplate and steerer tube, the stem is made up of a length of aluminium or carbon fibre, though titanium is occasionally used.<\/p>\n
The length of your stem can have a significant impact on the fit and handling of your bike. There\u2019s also usually a slight angle between the steerer tube clamp and the long axis of the stem. We\u2019ll explain the significance of both later.<\/p>\n
That\u2019s the basics covered but, as with all bike parts, there are exceptions and complications.<\/p>\n
The geometry of a bike stem<\/h2>\n
Stem length<\/h3>\n
![\""The\"]( "\\"\"Genesis\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Stem length has a big impact on the overall fit and ride of your bike.<\/span><\/figcaption> David Caudery \/ Immediate Media<\/i><\/span><\/div>\n The length of a stem is one of the most important factors to consider if you are looking to change the stock option on your bike.<\/p>\n
Mountain bike stems are typically around 50-80mm long, while road bike stems are longer, starting at around 80mm and extending to 120mm or longer as the frame size increases. Gravel bike stems typically sit somewhere between the two.<\/p>\n
Stem length is one of a number of factors, along with head tube angle and fork rake, that affects a bike\u2019s handling.<\/p>\n
Generally speaking, a shorter stem will result in faster handling, while a longer stem will result in slower, more predictable handling.<\/p>\n
As a result, fine-tuning the stem can be one way to tweak the handling of your bike \u2013 but remember, your stem doesn\u2019t exist in isolation and changing the stem length will also impact your position on the bike<\/a>.<\/p>\n
On that note, you can also change your stem length to adjust the reach from the saddle to the handlebar.<\/p>\n
A shorter stem will reduce the reach and provide a more upright position, which might help if you\u2019re feeling too stretched out. On the flip side, if you\u2019re feeling cramped on the bike, using a slightly longer stem will increase the reach.<\/p>\n
We\u2019d recommend experimenting with a different stem length if you want to make small, incremental adjustments to your riding position or the handling of your machine. However, a professional bike fit will help you hone in on the perfect setup, and factor in the influence of stem length on the rest of your position.<\/p>\n
Stem rise<\/h3>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>The increased stack, positive rise stem and bars here make for a truly lofty cockpit.<\/span><\/figcaption> Surly<\/i><\/span><\/div>\n Rise refers to the angle of the stem relative to the fork\u2019s steerer tube and typically ranges from six degrees to 20 degrees, though most stems fitted as standard on bikes are at the lower end of the scale.<\/p>\n
Most stems fitted on off-the-shelf bikes have a moderate amount of rise; however, stems with a more extreme amount of rise provide the option to significantly adjust the position of your handlebar.<\/p>\n
Stems are often designed to be flippable, so depending on the amount of rise, you can angle the stem down to achieve a lower, more aerodynamic position, or up to put the handlebar in a more upright position.<\/p>\n
Remember, though, that handlebar height<\/a> can also be adjusted via adding or moving spacers beneath the stem on the steerer tube or, on a mountain bike handlebar<\/a>, choosing a riser bar.<\/p>\n
Stem diameter<\/h3>\n
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<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Almost all mountain bike handlebars use either a 31.8mm or 35mm bar clamp.<\/span><\/figcaption> Ian Linton \/ Immediate Media<\/i><\/span><\/div>\n There are two diameters to get right when choosing a stem: that of the steerer tube and that of your handlebars.<\/p>\n
Both come in a variety of standards, which we\u2019ll come on to. Also, to add to the confusion, the steerer-tube diameter is normally quoted in inches and the bar diameter in millimetres.<\/p>\n
For steerer tubes, the typical diameter is 1-1\/8in, although some bikes will have a 1-1\/4in steerer diameter.<\/p>\n
Handlebars come in a range of diameters, so your stem\u2019s faceplate has to fit here, too.<\/p>\n
Modern road bike bars are usually 31.8mm in diameter at the centre, but older bars were more commonly 25.4mm.<\/p>\n
For mountain bikes, 31.8mm is the usual diameter, but you\u2019ll also find bars that are 35mm.<\/p>\n
How to measure stem length<\/h2>\n
![\""How\"]( "\\"\"How\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>How to measure a bike stem\u2026<\/span><\/figcaption> Stan Portus \/ Our Media<\/i><\/span><\/div>\n The length of a stem isn\u2019t its overall length, from the very front to the very back, but the distance from the central point on the steerer tube and the centre of the handlebar.<\/p>\n
It\u2019s fairly easy to measure with a ruler or tape measure. It\u2019s usually a discrete number of tens of millimetres (so 80mm, 90mm, 100mm), although really short stems can be 35mm long.<\/p>\n
Helpfully, a stem\u2019s length is often printed on it, often with additional information such as the rise and handlebar clamp diameter.<\/p>\n
![\""How\"]( "\\"\"How\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>You\u2019ll usually find the length printed on the stem.<\/span><\/figcaption> Stan Portus \/ Our Media<\/i><\/span><\/div>\n Adjusting a bike stem<\/h2>\n
There are a number of ways to adjust a bike stem to tweak the setup, fit or handling of your bike.<\/p>\n
If the fork is too loose or too tight in the frame, this is typically adjusted by loosening the stem bolts, pre-loading the bearings to the appropriate level by ensuring there\u2019s no play but they still turn smoothly, then re-tightening the stem to hold everything in place.<\/p>\n
![\""Headset\"]( "\\"\"Headset\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Ensuring the top cap is in place, tighten the bolt until you feel some resistance. This top-cap bolt is used to pre-load the headset bearings.<\/span><\/figcaption> Jem McPartlin<\/i><\/span><\/div>\n There are normally a number of spacers on top of the headset. You can raise and lower the stem, and with it adjust the height of your handlebar<\/a>, by moving spacers above or beneath the stem.<\/p>\n
Leaving your fork steerer long, initially at least, will give you some leeway to play with stem height by moving spacers from the top of the stem to the bottom.<\/p>\n
![\""Norco\"]( "\\"\"Norco\\"")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>This steerer tube is long enough to allow for plenty of adjustment.<\/span><\/figcaption> Ian Linton \/ Immediate Media<\/i><\/span><\/div>\n Speaking of spacers, there should always be a spacer on top of the stem if you have a carbon fibre fork, and the steerer should extend into the spacer. That way the full length of the stem clamp engages with the steerer, reducing the chance of damage to the top of it.<\/p>\n
You can also adjust the angle of your handlebar by rotating it in the stem clamp, assuming your bike has a conventional setup with a separate handlebar and stem.<\/p>\n
![\""Adjusting\"]( "\\"\"Adjusting\\"\/")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>Adjusting a stem faceplate.<\/span><\/figcaption> Oli Woodman \/ Immediate Media<\/i><\/span><\/div>\n For the flat handlebars<\/a> found on a hybrid<\/a> or mountain bike, adjusting the bar rotation when setting up your bike<\/a> allows you to alter the effective rise and backsweep of the handlebar.<\/p>\n
If you\u2019re riding a road bike or gravel bike with a drop handlebar<\/a>, the rotation of the bars will change the angle at which the handlebar drops and gear\/brake levers sit.<\/p>\n
- Stem length, rise and diameter<\/a><\/li>\n
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