Choosing front end cockpit components for your mountain bike can be confusing with the seemingly limitless array of choices and variables in standards, let alone the combinations in which they can go together. Mountain bike handlebars alone come in all manner of widths, sweeps, rises, clamp size or construction material.
Mountain Bike Handlebars’ Trends
The current trend in mountain bike handlebars is towards wide bars (720mm or wider) across all disciplines. This appears to have spawned from downhill in 2008 when riders like Sam Hill led the charge with 800mm flat bars. XC soon saw this trend cross over, as the wide bars were well suited to the new (at the time) 29” wheels — the only difference being a slightly longer stem on the XC bikes. This is all in sharp contrast to the early ’90s where 580mm wide flat handlebars and 120mm stems were the norm for XC, and 50mm stems with 670mm riser bars for downhill. These downhill risers are narrow by today’s trends, yet for racing they were strictly downhill with only the rebels like Geoff Kabush straying in XC racing.
Wide or Narrow?
The wide bars ‘revolution’ brought with it one distinct advantage — wide handlebars reduce the overall force required to turn via increased mechanical leverage. They also improved the handling of downhill bikes by bringing riders further forward to a more centred position. This last statement sounds a little counter-intuitive, so needs a little further demonstration: lean up against a table with your hands shoulder-width apart — notice how close your head is to the table. Now move your hands apart double this distance. You’ll notice that your head is now closer to the table. At this point, it’s worth mentioning that the current trend of wide bars / short stem in XC is actually rather closely related to former narrow bars / long stem approach — when properly setup, both position the rider equally over the front wheel.
So, I really haven’t simplified things in choosing mountain handlebars just yet, but we have seen that equivalent rider weight distributions can be achieved with different bar widths. When considering bar width for your bike, it’s important to understand its application: rider build, trees on your local trails, and terrain split can all have a significant impact on what is comfortable and practical. 800mm bars may be great on bermed bike park terrain, but they can be downright dangerous playing slalom through the trees (my gravel rash scarred elbows bare testament to this).
Alternatively, narrow flat bars have their niche in terrain with a greater emphasis towards road. Narrower bars coupled with a longer stem can be an elegant solution for racing on non-technical, fast terrain, particularly when a rider is used to spending long hours training on a road bike with nothing wider than 44cm bars. The position is familiar, and the handling is stable at speed. When racing European marathons, I used to use a set of 560mm flat bars (3 degree sweep) coupled with a 120mm flat stem. This was back in the 26” days in XC, and worked wonders for the open, fast, non-technical terrain, and familiarity when I was putting in 20-30 hour weeks on the road bike. So there are the two extremes, however at present I’m somewhere in the middle riding a 670mm bar with 70mm stem on a 29” XC hardtail.
Where to Start
If in doubt of bar width, purchase something wider than you may need and trial the grips at different locations, then cut the bars when you are comfortable with the set up. Aluminium bars can be cut at home with a pipe cutter, or a hacksaw if you are desperate. Finish the ends off with a file to remove any sharp edges. A word of warning: cutting carbon bars produces fine dust particles which are a health hazard. Do not cut these unless you know what you are doing with dust suppression, otherwise take them to your LBS.
When it comes to choosing between flat or riser bars, flat (or swept as they are sometimes called) bars are a more elegant solution than risers. Rise can more easily be adjusted through steerer spacers. For stem clamp size, 31.8mm is the most common on current bikes, 25.4 on older bikes, and 35mm is the industry’s latest “must have, but not reverse compatible” standard. I suggest keeping your options open if you are buying a whole cockpit from scratch and buy 31.8 — it’s likely stiff enough that you’d never notice the difference to 35mm ones.
The stem is the most critical component in achieving balance with your chosen bars, frame size and riding style. I personally prefer 4 bolt stems, as they distribute clamp load over a larger area on carbon bars. The optimum stem setup is achieved by adjusting the height and length so that at all terrain points you can comfortably look directly down and see the stem cap — shorter stems for downhill (where rider weight is further back for balanced descending) and longer for XC.
Longer stems give increased stability, which makes them suitable for high speed situations like road riding, while shorter stems help with handling in tight situations. Finding optimum length requires some time on the trail, and may require swapping out a stem at some point. Stems are cheap for the difference they can make to your riding. Borrow some off your mates, swap them round, or if none can be found, buy cheaper ones on sale. The correct geometry is more important than the weight or logo.
A good starting point for stem length is those commonly sold on OEM bikes of your size with similar bars. For example, at 179cm tall I ride a medium XC hardball, which typically comes with a 90mm stem and 700mm bars, so a 90mm stem is a good starting point if I want to run wider bars.
The final variable in the front end tuning puzzle is stem height, which can be adjusted by steerer spacers or flipping the stem. Most bikes come with around 15-20mm worth of spacers under the stem and 6 or 10 degree rise stems which can be flipped to add an additional 10mm or so rise or drop to the front end.
For those exclusively riding downhill, you can effectively ignore the last 2 paragraphs. Choose a 50mm flat stem, adjust the front end height of you forks to the frame manufacturer’s recommendations, and adjust bar height with spacers. I strongly suggest using a traditional stem that clamps to the steerer tube as opposed to the newer ones that clamp to the fork top crown. This if for 2 reasons: firstly this method allows the stem more movement up and down the steerer tube to fine-tune rider position; secondly — and perhaps more important to downhill riders — if you crash, the stem will twist. On direct mount bars, something else may give. A twisted stem is easier to fix than a broken set of bars.
Tuning bar height using spacers and stem orientation is somewhat similar to adjusting stem length, in the effect it has on rider position, just a little more subtle — a lower front end improves stability when climbing and cornering, however comes at the price of stability when descending on steeper terrain. Once again front-end height can be checked on the trail by looking down at the stem cap — if you are not looking down at it most of the time, the bar height should be changed. If bar height cannot be changed enough, it’s time to look at changing the stem for a shorter or longer one.
Finally, once the front end height and stem length is settled, it’s time to cut the steerer tube of the forks if you are keen, and only if you are keen. Not cutting a steerer means that forks may be easier to sell on the used market, as a longer steerer makes them suitable to more riders.
1) Select bars for terrain and rider build. I recommend an aluminium Easton EA70 Flat Wide Bar in 31.8mm clamp size, 720mm wide available from Chain Reaction Cycles for US$57.99
2) Select stem based on bar width and frame size. I recommend an Easton EA50 8-degree, 4-bolt stem with 31.8mm clamp size for initial setup available from Chain Reaction Cycles for US$55.99
3) Fine-tune spacers based on rider position. I suggest 15-20mm of spacers if setting up a fork and front end from scratch, most OE bikes will come with this
4) Re-select stem if not possible to tune with spacers.
Once you are confident with your setup, it’s now the time to buy the expensive stuff if you so desire. If you are running a stem with rise / drop and a steerer spacers, it is now possible to swap this out for a straight stem, or a stem with a different rise / drop and cut the steerer. If you do this, the same rules apply for cutting steerer tubes as for handlebars — send carbon ones to the capable hands of your trusted LBS.
For stem upgrade, I recommend my all-time favorite Thomson Elite X4 (0 or 10-degree rise). Depending on the options you choose, it costs between US$81.49 – US$92.99 from Chain Reaction Cycles
Thus far I have not mentioned assembling the components, or how it is best done. The whole front end is best assembled using a torque wrench to the stem manufacturer’s spec the first few times you do it, just to get a feel for how tight it all needs to be. Particularly so you do not go stripping threads on crushing bars.
How Headsets Work
At this point, I realised that it would not be possible to write an article like this without touching on the basics of how to put all the components together, since you’ll likely need to do this several times.
- Fit the stem and your chosen combination of spacers (above and /or below the stem) such that there is a 3mm or so gap between the top of the steerer tube and the last component on the stack when not clamped down
- Lossely tighten the stem cap
- Roughly align bars with the front wheel
- Tighten the stem cap to remove play in the headset, then add roughly 1/8 turn
- Re-align bars if necessary
- Tighten stem clamp bolts
Watch this video to help you with your installation:
One final word in bringing it all together is the contact point with your hands – grips. Since I started in mountain biking, MTB grips is one market segment that has just gone nuts, but has happily diverged into 2 easy segments. The first is the simplistic foam style grips, and the second is the moto / BMX derived lock-on grips.
My recommendations are foam grips (non lock-on style) for XC such as the Ritchey WCS Truegrip Foam Grips from Chain Reaction Cycles for US$12.49.
These grips come in a rubber version as well for US$7.49:
When installing any regular mountain bike grips, conventional wisdom is to use hair spray to stick the grips to the bars. My personal preference though is WD40 — it lubricates the grips going on, and acts as an adhesive after about 2 hours. It’s also pretty handy for removing grips — simply jam a screwdriver down between the grip and the bar, and spray a little WD40 to get the grip moving.
Outside of XC racing, it’s tough to beat the convenience of lock-on grips. It’s also tough to beat the comfort of a large rubber grip. My vote is for the classic – the Oury ODI Lock-On Grips available from Jenson USA for US$24.95.