50mm stems - improve handling or too short?

When it comes to mountain bikes there are many components that split opinion and stem length is definitely one of them. I’m a firm believer in the merits of a 50mm stems on any bike.

For me it is a simple matter of physics, balance and control. I’m also of the opinion that the 50mm stem is a great leveller when it comes to nailing down the performance characteristics of different bikes. I would much rather ride a bike with geometry and ‘fit’ that complement a 50mm stem than create the correct reach through fitting a larger unit. A longer toptube and the resulting wheelbase usually equates to a more stable handling bike anyway.

The more directly you are over the centre of the front wheel the better. If I want the force of my weight to be transferred anywhere when going forward I would rather that force to be as direct as possible towards the centre of the front wheel and through the suspension.

This may be less of an issue if the terrain is particularly mild or if you are doing most of your miles on the road where aerodynamics and pedal efficiency take precedent over weight transfer and dynamic body position.

Running a 50mm stem has saved many an over-the-bar moment, giving me and my upper body the ability to take a hit and push that force back into the wheels instead of sending that force over the bars away from the forward momentum of the wheels and out of my control. I believe they are safer for this reason – ou are forced to ride a little further back on the bike and as a result you ride ‘in’ the bike more. Lengthen the stem and your bodyweight is constantly being shifted out of line with the bike. You are forced too far forward and forever on the edge of being pitched over the bars.

I want to know that any downward force I put into the bars is being directly translated to the tyre. If I push down I want that force to compress the tyre into the ground. As we already know, more pressure on the tyre is going to equate to more grip. A shorter stem puts you further back on the bike meaning your weight is always pushing the bike forward and carrying momentum while maintaining balance and control.

Picking the front of the bike up and pumping through terrain is also a lot easier to do with a shorter stem. However, climbing with a shorter stem the front end is essentially unweighted. This is something I have no issue with and it is something that you quickly get used to, and with the range of adjustability around these days, dropping the forks will add more weight over the front-end when climbing anyway. The advantages the shorter stem has in all other areas of handling and control far outweigh this minor niggle.

Why any complete mountain bike (aside from cross country race bikes) comes fitted with anything longer than a 50mm stem remains a mystery to me.

Do you agree with Jon? Leave your reaction in the comments box below:

  1. serge the seal of death

    juat about to swap my 70mm stem for a 50, just need to find a nice one,
    when i have done this on other bikes i was amazed at how the riding charateristics of the bike has been changed, probably only other time was going to wider risers from XC bars back in the day and suspension.
    only thing holding me back at the moment is getting the right stem and not paying to much as i like a bargin but also a brand name.

  2. hugobball

    I ride the one in the top picture, a THOMSON ELITE X4 50mm, it’s a great piece of industrial design, and is though as hell!

  3. chris-m

    Surely depends on the bike?
    If the top tube length can handle it and doesn’t result in it being too cramped, then perhaps. But it’s down to the bike and the genre of bike. I mean, you’re hardly going to stick a 50mm stem to an XC bike with a 71 degree headangle!?
    I would say, IMHO, that approx a 70mm is more than adequate for most situations without causing too much havoc, but again, it’s down to preference. Some may prefer longer for a slightly slower steering feel. Each to their own.

    As a personal note, it would be good if manufacturers made top tube lengths long enough for the consumer to fit a shorter stem and still have enough length for longer rides.

  4. Martyn Kelly

    I’m about to fit a shorter stem just to see what the bike feels like but as my bike has a 71 degree HA and I mainly ride trails I’m fairly certain its going to be very twitchy.

  5. jedi

    going over the bars is about rider position and levers not stem length

    1. Andy

      Could say the same about head angle? Fact is it makes a difference, and all differences add up, including body position. I was doing some stairs and at the bottom nearly went over the bars, saved it by pushing forward. Short stem helped for that.

  6. oldnick

    I tried a short stem a couple of years ago, it put my weight further back on the bike which un-weighted the front wheel and lost me traction. Plus the bike spent its whole life wandering about uphill with an un-weighted front wheel.
    Unless the bike has a long top tube you end up with the riding position of spinster riding to church, not my scene.
    Surely so long as the stem and steerer are rigid the weight transfer will still find its way to the front suspension? I haven’t noticed my 90mm Hope stems flexing madly, but then again I wasn’t looking.
    As for a short stem being safer? Utter bollocks. An efficient position can be made to work in the technical sections by moving your body around. Maybe I’m alone in having a body with numerous joints that can flex and extend through quite a range of movement in order to put my centre of gravity where I want it regardless of stem length?

    1. Andy

      I think you’ll find he said that it depends on the bike’s top tube length (obviously). If it’s obviously a short reach for your body already, then no point putting in a small stem. Varies from person to person, as some have monkey arms, some don’t.

      1. Andy

        But can always find a bike to suit a small stem & your body, as top tube lengths vary quite a lot. Plus many “new school” bikes are designed with extra long top tubes just to make use of a short stem (e.g. Ragleys where would be crazy to run a long stem).

  7. james

    Why not a 40mn then?

  8. DanLees

    There is loads more to this than just “slap a short stem on”.

    Handlebar width, Effective TT, HA, etc…

    Putting a short stem on without changing bar width is a mistake in my experience.

    Same bike with 50mm stem and 680mm bars felt wrong. Changed bars to 760mm and it feels spot on.

    Remember the wider bars will help climbing also as they open your chest, longer lever for out of the saddle climbing, and brings your weight forward when seated.

  9. simon spragg

    Swapped my 110 for a 70. 1st ride tonight having fitted the new stem in the car park was to say the least technical up / down with loads of twisty singletrack in between. The difference is simply INCREDIBLE, just do the upgrade. Oh and forget about climbing being a handful I just nailled two never before cleared uphill sections without changing the fork travel just left my sektors in 150mm mode.

    1. Joel M

      Thanks, you’ve just swayed it :D

  10. Kevin James Scullion

    Hi there. Great advice, cheers.
    Got a Cannondale Badboy Fatty R9 a year back. After wanting to change the tyres to Continental Gator’s, I’ve decided to change the stem for something much smaller than the C4 that came with the bike. I know the bikes a hybrid for the road, but I’m daft that way, so a shorter stem it will be. Childishly, I think it looks much cooler. The Thomson Elite X4 Stubby MTB in the 50mm is just a block of pure brilliance to look at. Plus every review on the net from professional and non-professional riders gave it a thumbs up. The 70mm version completly changes the look back towards the traditional smoother tube design. As to the 50mm version on a Fatty R9. Well, I’ll take every bit of advice from the Evans Cycles people. But I’m also thinking about the actual slow turn effect it’ll have on my bike. As the C4 stem is nasty at slow speeds – lights,traffic jams etc. As for going up hill. I already have long Bontrager bar ends on my wide bar. And my feet are clipped in, so I just stand out off the saddle, grab the bar ends and power up with my weight over the front end. Thanks for the brilliant knowledge sir.

  11. Jeremiah

    I sure hope you folks are right, for various reasons I decided to change the 100 mm stem on my MTB to a 60 mm and tomorrow is the first ride !

    1. Jeremiah

      Hi,
      I can report a great improvement in my technical riding down rocky slopes and over drop offs, the feeling of going over the handlebars has seriously reduced with the shorter stem and I am now riding terrain I could not previously do. This has been a great learning experience for me. I am also still OK to cycle up rocky climbs, not quite as stable as I felt before when I leant forward but none the less quite OK, perhaps I am at the middle spot of just far enough forward and just far enough back. Happy for now :-)

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