Bike stems look like a standard equipment without any science to it, however, they are highly influential when it comes to comfort and control. The wrong stem length will not only make it difficult to reach for the handlebars, it will also destabilize the steering and affect body position on the bike. Cross-country and leisure oriented mountain bikers are more concerned with fit than handling when it comes to stem length. Competitive cross-country racers generally have stems with a negative angle or drop whereas recreational riders commonly have stems with a slight rise. Comfort and Cruisers The major determinants for stem cost are weight, stiffness and type of material used. Mountain bike stems are normally more robust and less concerned about weight than road stems. Stems are composed of steel, aluminum, carbon fiber or titanium. Aluminum is the most widely used material. Steel stems are cheaper but heavier, while carbon and titanium stems are lighter but more expensive. Along with saving weight, carbon fiber also helps to dampen road vibrations. Found on some mountain bikes and also some drop-bar machines such as Giant’s cyclocross bikes. 1 1/8in steerer, 35mm bar clamp

Older bikes have a 1” steerer but these are becoming rare and any stem to fit these types will be clearly labelled. Bike stems range between negative 10 to positive 17 degrees. When a stem has a positive degree, it is called a “rise”. The stem with a negative degree is commonly referred to as “having a drop”. The higher the stem rise is, the more upright your position will be. Alternately, the lower the drop of the stem is, the more aggressive your bike will feel. Handlebar stems look like a fairly standard piece of equipment but have a massive influence on control and comfort. Get the wrong size stem and not only does reaching the bars become an issue but steering as well. The majority of riders will appreciate a fairly low angle ie. less than 10° as this gives a fairly neutral position with just a low rise. Leisure riders will appreciate a more upright position. Racers will try to get a low as possible for better aerodynamics. Stems are labeled in two different ways: either (1) the actual angle, or (2) in terms of their difference from 90 degrees. I guess, the numbers are based on mounting the stem on a perpendicular tube, but they have nothing to do with head tube angle on your bike.

Hope Gravity Stem

Stem length is one of a number of factors, along with head tube angle and fork rake, that affects a bike’s handling. When choosing a stem the main things to consider are length, rise, bar diameter and material. Don’t get too hung up though, it’s a relatively easy decision making process when deciding what’s right for you. 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. Don’t forget that you can also probably raise and lower your stem by moving the spacers around on the fork steerer. Often all it takes is to swap a 10mm spacer from being under the stem to being over the stem to make all the difference you need.

Steering is also affected by stem length; too long and the steering can become slow and wayward while too short and the steering can be twitchy and unnerving. A lot of positioning and responsiveness depends on the length of the stem. While road riders choose their stem length based on bike-fit and positioning, off-road riders often determine stem length based on how the bike handles. would rise or drop 6 degrees if the steer tube were perpendicular. This would rise a little more than the 90/0 if in the "flipped up" position, and would be lower in the flipped down position.

A shorter stem will reduce the reach and provide a more upright position, which might help if you’re feeling too stretched out. On the flip side, if you’re feeling cramped on the bike, using a slightly longer stem will increase the reach. The only exception to this handlebar clamp size is the new Deda 35 system which is, you’ve guessed it, 35mm and needs a corresponding bar and stem. NB: some manufacturers quote the other way ie 83° which in reality is a 7° rise so don’t expect a near vertical stem! As a rule of thumb, on a road bike you shouldn’t run a stem much shorter than 90mm or much longer than 130mm. If you need a stem length beyond those extremes, your bike frame is the wrong size. Sorry! Rise Newer bikes most likely require stems with a 1 and 1/8 in. steerer tube clamp and an oversized 31.8mm handlebar clamp. On average, it is best for casual riders to have a longer stem (70mm to 120mm) with a positive (6 to 10 degree) rise. It is worthwhile to discuss stem options and fit with qualified staff at your local bike shop.