# Thread: Lean Angle and Tire/Rim Choice

1. ## Lean Angle and Tire/Rim Choice

Is there an 'optimum' lean angle for hard cornering technique on mostly flat trail (no berm)? I ask because there is so much confusion about what tire matches what rim width. Can't you quantify whether the tire fit is correct by seeing what lean angle the side lugs are down?

I just put a Maxxis Minion DHF 29x2.50 WT on a 29 mm internal width rim, and I have to lean the bike 35 degrees down from vertical for the side knobs to be flat on the ground. That seems like a pretty far lean, but maybe it is the extreme angle I would do on a trail. I plan to get some wider rims, but I don't know if I want to go up to 35 mm.

I just want make sure my corner lean technique is correct before I spend money on the wrong setup. Mechanical engineers like specifics haha.

2. Keep in mind leaning your bike over statically will not take into account tire deflection from weighted riding or g-forces. The 2 really have nothing in common. I find on lose bermless trail leaning my bike over but keeping my body more upright to keep as much weight over the tire as possible works best.

3. Bike leaned 35 degrees.

4. My front 29mm internal, 2.5 WT shows a lot of wear on the cornering knobs, and I haven't washed oust I'm assuming that it's ok.

5. Lately I have been experimenting on leaning my bike more or less in corners. I can get around the corner either way, but I figured the pros were taught what angle is best.

6. the thing that will change the lean angle would be tire pressure, and rider weight. The lower the pressure or more weight applied to more the tire will deform and flatten out. A extreme example of this would be drop the tire pressure to only a couple psi so the weight of the bike will cause the tire to deform and flatten out while standing straight up then lean bike over. I do not think that there is one set equation for lean angle and rim/tire size due to so man variables, ie hard vs soft ground ( tire sinks into ground engaging side knobs sooner), tire pressure, rider weight, undulating terrain ( even factions of inches can effect angles higher or lower). Most pros that I know just ride how and what works for them to get down the trail the fastest and leave the thinking and angles up to the designers that base it off what their test riders and pros tell them what works best on the trail.

7. The lower the pressure the bigger your footprint. What pressure are you able to get down to before you get rim hits?

8. More or less pressure, more or less angle, more or less anything is actually completely dependent on the terrain, tire shape, riding style, and other individual feel.

I don't like low pressures. 24-24.5 is about all I run on my Remedy. Lower than that, and the tire does not feel good. It does not want to swap back and forth well. I have been tempted a few times to go up to about 25-25.5 again. Sometimes on the chunkier terrain, the tire does not hold it's corner as well as I think it should, likely due to deformation from a surface abnormality.

I also don't like square profile tires. I like more rounded profiles, for easier back and forth switching. The bike wants to lean over on a more rounded profile tire.

Analyzing lean angle as if you are "properly" cornering is way over thinking it.

9. Interesting topic here - I'm a mechanical engineer myself and have been trying to find the rim/tire width sweet spot.

Test 1 - "Plus Tires"
35mm internal rims w/ 2.8 Schwalble Rocket Rons 14-16psi
With this setup, the tire had a crazy rounded profile. To the point where I drug my handlebar on the ground on a sandy bermed corner. Looking at the tire tread blocks, I noticed that I rarely used the outer knobs as well. That being said, I always had plenty of grip, but the bike really needed to be leaned over to corner well. I wasn't a huge fan of this as I'd like the bike to be more responsive before the handlebar is slammed on the ground. This was an extreme case though...35mm rims are a narrow for plus tires.

Test 2 - 2.6in Rekon
32mm internal rims with 2.6 Maxxis Rekon 21psi
I tried this tire up front and was surprised with how rounded it mounted up. After my first ride, I instantly realized that I had to lean the bike over more to get it to bite in corners. Definitely not as drastic as the plus setup above, but it was noticeable especially on flat corners. I can also add that the grip was predictable through lean angles. After riding the tire/rim combo for a month, I went back with a narrower and more meaty tire (2.5 DHF). Maxxis spec's the 2.6 tires for 30-35mm rims......but I'd steer folks towards 35mm rims if they dont like being aggressive with lean angles.

All in all, I wouldn't say a rounded profile is a bad thing. It just depends on your riding style. If you don't mind being active on the bike and laying it over, then rounded is ok. Another thing to keep in mind is the trails you ride. IF you ride trails with lots of trees like I do, it makes it difficult to swoop turns due to trees mid-corner. This was the case for me in the the Carolinas. If you have wide/open trails, the extra lean angle would be much more welcomed.

10. Originally Posted by jlbanta
Interesting topic here - I'm a mechanical engineer myself and have been trying to find the rim/tire width sweet spot.

Test 1 - "Plus Tires"
35mm internal rims w/ 2.8 Schwalble Rocket Rons 14-16psi
With this setup, the tire had a crazy rounded profile. To the point where I drug my handlebar on the ground on a sandy bermed corner. Looking at the tire tread blocks, I noticed that I rarely used the outer knobs as well. That being said, I always had plenty of grip, but the bike really needed to be leaned over to corner well. I wasn't a huge fan of this as I'd like the bike to be more responsive before the handlebar is slammed on the ground. This was an extreme case though...35mm rims are a narrow for plus tires.

Test 2 - 2.6in Rekon
32mm internal rims with 2.6 Maxxis Rekon 21psi
I tried this tire up front and was surprised with how rounded it mounted up. After my first ride, I instantly realized that I had to lean the bike over more to get it to bite in corners. Definitely not as drastic as the plus setup above, but it was noticeable especially on flat corners. I can also add that the grip was predictable through lean angles. After riding the tire/rim combo for a month, I went back with a narrower and more meaty tire (2.5 DHF). Maxxis spec's the 2.6 tires for 30-35mm rims......but I'd steer folks towards 35mm rims if they dont like being aggressive with lean angles.

All in all, I wouldn't say a rounded profile is a bad thing. It just depends on your riding style. If you don't mind being active on the bike and laying it over, then rounded is ok. Another thing to keep in mind is the trails you ride. IF you ride trails with lots of trees like I do, it makes it difficult to swoop turns due to trees mid-corner. This was the case for me in the the Carolinas. If you have wide/open trails, the extra lean angle would be much more welcomed.
That's very interesting. My Fuse came with 3.0s on 38i rims, and although it grips great the outer tread only touches protruding stuff.

Your recommendation of a wider rim is what I was interested in because it seems with my 2.5wt on a 29i makes you have to lean quite far. That's a problem for trees like you said but also for all the energy it takes throwing the bike around.

Thanks

11. Originally Posted by TNTall
Lately I have been experimenting on leaning my bike more or less in corners. I can get around the corner either way, but I figured the pros were taught what angle is best.
The best bike lean angle is the one that gets you round the corner the fastest. Leaning the bike more has the effect of reducing the turning radius, which means you don't have to turn the front wheel into the corner so much, which means the front wheel isn't scrubbing so much, which means you maintain more speed. In theory, the fastest lean angle is the largest lean angle possible before the inside pedal or bar end hits the ground, but in practice there are limitations on lateral grip and tyre deformation that set the limit for the bike lean angle.

Though this is all just Newtonian physics, it is insanely complicated to work out as there are so many variables involved. Pro riders generally don't sit at home working out force vector diagrams, they go by feel based on huge amounts of experience. As far as bike lean angles go, the angle is about right if the steering feels light. If you're having to wrestle the bars towards the outside of the corner then you're leaning too far, and vice-versa.

This is just bike lean angle: body lean angle is a whole other discussion, but basically if you're not crashing on every corner then you've got that right as it's a basic requirement for being able to ride a bike. "Lean the bike more than the body" is sound advice for almost all MTB flat-cornering situations, but it's not true that weighting the outside pedal gives better grip by increasing the weight on the tyres. It does help with cornering, but not for that reason.

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