A 120mm stem? Absolute perfection.
I love putting long stems on my bikes, but despite my vanity, it's not for aesthetic reasons. It’s actually very rare for bikes to come with the right stem length out of the box. I’ve had to change the stem on every bike I’ve bought. As a result, I have a bin full of bike stems in my garage.
Stems are the most useful component for perfecting your bike fit. If you want to improve your comfort and position on the bike, then getting the right stem is key. Here’s how I discovered my perfect stem length.
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Bike Fit Matters (Duh)
Let me preface this by saying I’m not a professional bike fitter. In fact, I rely on a professional bike fitter to perfect my bike setup and I think a good bike fitter is worth every penny. What I want to do here is relay one of the surprising lessons I've learned after a bike fit and thousands of miles in the saddle.
I’ve dealt with a few specific issues with my bike fit over the years:
- My right hand goes numb
- My triceps and right shoulder get achy
- My lower back tightens up on long rides
When I started upping my mileage and competing in more long-distance races, I realized I needed to fix these issues or I’d probably end up miserable and injured.
It’s About the Weight on Your Hands
For me and my bike fitter, the main goal of adjusting stem length is reducing how much weight is on my hands. Unless your riding position is bolt upright, you will always have some amount of pressure on your hands. But if you have too much, it will negatively affect your comfort and performance.
The right stem length (and bar height, but let's keep this simple) produces a position where the upper body is in a state of balance. Your core/trunk can do most of the work of supporting itself, and there is minimal pressure on your hands. This lets you ride more comfortably. You can ride longer and farther. Because you’re devoting less energy to supporting your trunk with your arms, more energy can go toward turning the pedals, improving your performance too.
Important Note: Saddle position and bar height are essential parts of the fit equation too. You should only play with stem length/bar position after settling on your saddle position.
With numbness and pain in my hands, triceps, and shoulder being my top issues, it seemed clear that I was putting too much weight on my hands in my current riding position. I figured I must be too stretched out. So I did what many riders do to try and get relief: I purchased a shorter stem.
Long Stems Were the Unintuitive Solution
Jason at Retul used a special jig to experiment with different stem lengths.
Unfortunately, trying a shorter stem didn’t cure any of my issues. I went all down to an 80mm stem on my medium Lynskey gravel bike (I’m 5’8, usually riding a size small or medium) but I still had a lot of weight on my hands. I was starting to get super frustrated with my bike. (I also played with bar height which helped a little, but not as much as I hoped.) In desperation, I finally ponied up the money for a bike fit, and went with the best in the business: Retul.
If you don’t know, Retul is a premier fit system used by countless pro cyclists and teams. It uses 3D motion capture technology to get your bike fit millimeter perfect (read more about my Retul fit experience). My fitter, Jason Williams, made several small changes to my bike that had a positive impact on my riding comfort. But the biggest change he made was to my stem length.
During my fit session, Jason replaced my stem with a special jig that allowed him to instantly adjust my stem length. He started at the stem length I came in with, and as I pedaled on a stationary trainer, he slowly increased the length a few millimeters at a time. I felt myself getting slowly stretched out, and then, something interesting happened. My torso dropped lower, and suddenly, I felt very little weight on my hands.
“We went much longer, and your upper body immediately relaxed into the position. It’s exactly what I want to see, you started holding yourself up with your core. Your arms weren’t stiff and straight anymore. You had a nice, relaxed bend at the elbow.” - Jason
This was a shocking discovery. My own intuition has told me that I needed to shorten my bike to get more upright and reduce the weight on my hands. I’ve seen countless internet comments suggest the same. When Jason suggested going longer, I almost didn’t believe him. When he kept extending his stem jig past 100mm, I thought there was no way it could be right.
But once we hit 120mm, it was like magic. Instead holding myself up with my arms, I was hinged at my hip and holding myself up with my core. While pedaling, I could release my hands and my trunk would remain in the same position, essentially floating. What we discovered is that my torso is quite long relative to my legs, and pretty much every bike in my size comes with a stem that is way too short.
I’ve since taken this information and applied it to every single bike I’ve owned. Depending on the reach/top tube length, I use different length stems to achieve the same position Jason put me in all those years ago. My size small Lauf Seigla came with a 70mm stem and I went up to a 110mm stem. My 52cm Specialized Aethos came with a 90mm stem and I went up to a 120mm stem. My 54cm Specialized Allez Sprint came with a 100mm stem and I went up to a 120mm stem.
Interestingly, my wife just recently went through a very similar experience. She was experiencing hand numbness and shoulder pain on her 49cm Specialized Diverge. She went and got a Retul fit and her fitter swapped her stock 60mm stem for an 80mm, which made her pain disappear in the same way it did for me.
Short Stems Might Also Be the Answer
So is the lesson here that everyone needs a longer stem? Heck No. People with different proportions may find they need a shorter stem.
I think the main lesson is that you shouldn’t be satisfied with a poor-fitting bike, and experimenting with your stem length can be the key to unlocking the perfect fit.
These days, I can do 200-mile races, and stay on my bike for 12+ hours without hand pain or numbness, or any of the other issues I had. That’s an amazing improvement. Because I’m comfortable, I love riding more than ever.
The second lesson is that getting fit by a good bike fitter can be the best thing you can do for yourself. Sure, you can figure things out through YouTube videos and experimentation, but sometimes it’s easier to get a solid baseline from a fitter.
Fitters can also often discover and fix things that are just much harder to figure out on your own. With stem length, going longer went against all of my instincts. I thought I had excessive weight on my hands because I was too stretched out. Without Jason and Retul there to guide me, I’m not sure I would have arrived at my current fit.
How To Experiment With Stem Length at Home
Behold, my bin of stems.
Of course, not everyone can afford a $400+ dollar Retul bike fit. So what if you want to experiment with stem length on your own?
Earlier this year, my friend was complaining about his bike fit. So we ordered 5 stems from Amazon for about $10 each. We picked up a few stem that were longer than his current stem and a couple that were shorter. Then we swapped them out one by one and went riding. Now, these cheapo Amazon stems are NOT stems that I’d trust for any sort of performance cycling. So once we found the most comfortable length (like me, he also ended up going much longer), he purchased a higher-quality stem to replace it.
If you’re connected with your bike community, you can ask around to borrow stems. Remember that bin of stems I have? I’ve loaned out different length stems to countless riders who are trying to fine-tune their fit.
How to change/adjust your bike stem
Are you unsure of how to change or adjust your stem? I made a video just for you! It’s super easy:
The above video works for any bike using a standard threadless stem — i.e., most modern road, gravel, and mountain bikes. If you have a bike with a proprietary stem or integrated bar and stem, then you may need to buy specific stems or bar/stem combos and follow the manufacturer’s instructions.
If you ever need help finding the correct parts or want some advice on easy tweaks you can make to your bike fit, then reach out to one of our expert Ride Guides. Their whole job is to make sure people are happy with their bikes and they can offer advice via chat, email, or over the phone.
Hopefully, this has inspired you to think about how you can improve your own bike fit. Take a look at your stem. Is it really the right length? You might not even need a drastic change like me. You may be only 10mm from perfection. But you’ll never know unless you start actively trying to improve your bike fit.
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