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What is your preferred weight ratio between front to rear wheels on your bike(s)? I always assumed 40% front / 60% rear was "normal". I have been experimenting with tire pressure and stem length trying to improve front tire grip and steering on my trail bike which is often slipping in corners.

These are the front / rear weight ratios I measured on my bikes:

Full suspension MTB: 38% / 62%
Hardtail MTB: 39% / 61%
Cyclocross: 42% / 58%

(Methodology: me on bike with one wheel on a scale and opposite wheel slightly elevated to compensate for height of scale)

The frequently referenced Frank Berto tire pressure experiments assumed a 45%/55% ratio. Those were road oriented tests. I'm guessing I might get closer to 45/55 on a road frame. But I am no where near that on my mountain bikes and was surprised to find I was slightly below 40% front weight on both bikes.

Has anyone else ever actually checked this for themselves? What ratio do you have? Have you tried to alter your ratio?

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    > What is your preferred weight ratio between front to rear wheels on your bike(s)? — a "preferred" value is certainly an opinion-based thing, and such an answer does not adhere to the rules of this site (here, we strive to post/answer/discuss more or less objective things). Commented Sep 1, 2020 at 18:53
  • Data points: My bent is 52% front and 48% rear whether I'm seated on it or not. My folder is 26% front and 74% rear because of the upright seating position.
    – Criggie
    Commented Sep 1, 2020 at 19:30
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    A nice example of 60:40 within rounding error. I don't know how you're staying upright, but try moving your bodyweight around as much as you would when riding. Thinking of the hardtail, sit as if riding a nice road to the trails, then get into attack position.
    – Chris H
    Commented Sep 1, 2020 at 19:31
  • Unfortunately my digital scales try to be helpful end up up being really annoying for this sort of thing, or I'd see what my tourer does
    – Chris H
    Commented Sep 1, 2020 at 19:32
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    Unicycle 100% weight distribution on the wheel. For completeness.
    – Criggie
    Commented Jul 17, 2022 at 2:55

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After wondering about the same question myself I decided to weigh the front and rear tires of my bike was sitting and standing. I used the same compensation by raising the non- scale tire to match the scale. My ratios were close to 62 and 38%. Consistently. Both standing and sitting very close. I also found it my digital scale would not get consistent readings, so I actually bought an analog scale for this purpose.

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  • To be clear, that's 62% on the front tire and 38% on the rear? What kind of bike is it?
    – sjakobi
    Commented Aug 21, 2023 at 19:10
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This is not really an answer but a long comment.

The trick word is "optimal". Optimal for what?

For an MTB rider, where riding conditions are extremely dynamic, weight distribution will change a lot during a ride.

One such variable is terrain incline. While ascending weight is shifted towards the rear wheel. Descending is the opposite.

Other variable is whether you are braking, as it shifts weight towards the front.

Depending on your riding technique you can intentionally shift your weight in any direction to further assist your maneuvers. Getting out of the saddle gives a wider range of motion.

Specifically on getting traction in the front wheel I have found that:

  1. For cornering a tire with tall knobs is better, if those knobs are elongated and placed more longitudinally (in the direction of tire rotation), even better. A good tire with a good thread pattern and good compound saves a lot of pain.

  2. While descending I lower my torso to have a lower center of mass, which allows for a slightly more weight being applied to the front tire while diminishing the possibility of being thrown over the bars. (I can brake and corner harder while doing this than while not).

  3. For cornering either on flat or descending, slightly bend your elbows outward and move your chest a little towards the handlebar. This puts a little more weight on the front tire and also puts you more into the "attack position" where the arms are more ready to react in case of slippage, some times even enough to recover promptly, re gaining traction in a fraction of a second. This also makes your arms assist the suspension. It's specially useful when using a stiff suspension or a rigid fork.

For both 3 and 4 (which are almost the same thing) I'ts often necessary to move the butt out of the saddle towards the back to compensate. Both pedals should be at the same height and both knees slightly bent.

  1. Brake balance: In some parts of the trail I apply the rear brake not for speed reduction, but to put more weight into the front tire, increasing how much friction it can provide. When going over slippery stuff (a wet tree root, mud patch, etc) with the front tire I release completely the front brake until I'm again over more favorable terrain.
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  • "Optimal" for overall riding as a static starting point. Obviously you can shift your weight and body position all over the place while riding. That takes energy. If you need to move your body position very much then I assert your neutral starting position was not optimal. Finding an optimal starting position means you are riding more efficiently and should not need to move very far from that position to climb or descend or corner effectively.
    – Jeff
    Commented Oct 2, 2020 at 21:18
  • @Jeff I disagree with "if you need to move your body position very much then I assert your neutral starting position was not optimal". Situation determines body position and it can change dramatically from "optimal" static. It would take a large matix to capture all of the possible bikes/terrains/situations possible.
    – David D
    Commented Aug 21, 2023 at 15:28
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For completeness:

Recumbents Both of mine are within 1% of 50/50 weight distribution, depending on what luggage I have loaded.

Carrying my work laptop and lunch and spares might get it to 52% rear but that would be unusual.

Under hard-stop braking, the rear wheels are very easy to skid regardless of V brake or disk brakes, but the front loads up and does almost all the braking work.

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I have been experimenting with tire pressure and stem length trying to improve front tire grip and steering on my trail bike which is often slipping in corners.

I cannot see how tire pressure can affect weight distribution in any measurable manner. A very minor effect on the static weight distribution may perhaps be observed on a fat bike, where a severe underinflation of one tire actually changes bike's geometry (by visibly raising or lowering one of its ends). Adjusting tires' pressure may help with getting a better traction, but the involved physics do not have much with the weight distribution to do.

Changing stem length is obviously a different story, as a longer stem may force the rider to shift their center of mass forward.

I'm guessing I might get closer to 45/55 on a road frame. But I am nowhere near that on my mountain bikes

I do not see how a "recommended" weight distribution, if there was such a thing at all, provided for a road bike can be applied as a measure of anything for a mountain bike. These types of bicycles have different dynamics and areas of use.

If we track trends in changes of static weight distribution for mountain bikes over the last three decades, I am sure that we will see a trend of weight shifting from front to rear. MTBs of 90's were inspired by road frames, and modern MTB's tend to have rather short chainstays.

What really makes these numbers irrelevant is the fact is that under braking/acceleration the weight distribution between front/rear wheels is nowhere close to the static values.

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  • Grigory, the relationship is the other way around. Weight distribution determines tire pressure. If you have 40% total rider + bike weight on front tire than in theory the front tire should have 2/3 pressure of the rear. Or at least that is the premise I am working from. I am trying to determine if many other people are finding similar 40/60 type ratios on their mountain bikes. As I too am sure road frames and 90's era MTB's would be much more forward positioned due to steeper head and seat tubes.
    – Jeff
    Commented Sep 2, 2020 at 19:28
  • The values are certainly not irrelevant. Clearly you must start with a static measurement. That is how you set up suspension. Further adjustments can be made based on riding. If you start with a 50/50 ratio then braking or descending would clearly push you even further forward perhaps to 60/40. I have no practical way to measure that while riding. I'm just looking for a reasonable static starting point.
    – Jeff
    Commented Sep 2, 2020 at 19:35
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I have been experimenting with tire pressure and stem length trying to improve front tire grip and steering on my trail bike which is often slipping in corners.

There is only one answer to this question you didn't ask.

If you want to set tire pressure based on weight distribution, the front tire should have more pressure than the rear tire. However, for practicality I just inflate the rear tire to the same pressure as the front tire.

The reasoning is as follows. There is a condition where the front tire has 100% of the rider's weight. There is a condition where the rear tire has 100% of the rider's weight.

A rear tire has 100% of the rider's weight when you are riding up a very steep hill seated using a low gear. In that case, you're traveling very slow, so slow in fact that pinch flats due to road imperfections aren't a threat. So tire pressure doesn't matter here.

A front tire has 100% of the rider's weight when you are going very fast and braking very hard, so hard that the rear tire almost rises to the air. In this case, it's realistic that there's a rock or a road imperfection, and you are going very fast over it, and it could cause a pinch flat. In fact, in many cases you notice some road imperfection, brake hard, and arrive at the road imperfection riding too fast, with all of your weight on the front tire since you are still braking.

So rear tires generally don't pinch flat in situations where you have 100% of your weight on the rear tire.

But front tires can and do pinch flat in situations where you have 100% of your weight on the front tire.

Therefore, the front tire should have more pressure.

However, since the pressure you use on the front tire has to be adequate for the tires and can't sacrifice riding comfort too much, why not use that pressure on the rear too? It can further reduce total rolling resistance if you just simply set the same pressure on both tires.

Has anyone else ever actually checked this for themselves?

Yes. I have ridden seated using low gear in steep uphills. I have also braked very hard using the front brake only.

What ratio do you have?

Sometimes, 100% on my weight on the front wheel only. Sometimes, 100% of my weight on the rear wheel only.

Have you tried to alter your ratio?

Yes. I alter it for example by adjusting how hard I brake. I also alter it by choosing whether to ride steep uphills seated or standing. I also can alter the ratio when braking hard by moving my body more to the rear, allowing me to have more braking force -- yet that more braking force actually cancels my attempt to alter it, since 100% of my weight is on the front wheel only due to the harder braking it allows.

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  • OP was concerned about grip on an off-road bike. In such scenarios you are unlikely to be able to brake hard enough to unload the rear wheel. For more or less pure road cycling I’d inflate for least rolling resistance, which is usually also enough pressure to avoid pinch flats and doesn’t have much effect on grip anyway (since tarmac is pretty smooth).
    – Michael
    Commented Aug 20, 2023 at 17:21
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    When going off-road in situation that could move 100% of the weight to the front wheel, the correct behaviour is to move the body as much rear as possible, because having the weight front is bad — it's in fact a braking technique for roadies as well. You also need grip on the front grip, and you get grip by lowering the pressure, otherwise you just bounce. So the correct practice is lower pressure front.
    – Rеnаud
    Commented Aug 20, 2023 at 18:33
  • 1% of the time, it works every time
    – Swifty
    Commented Aug 20, 2023 at 19:29

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