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Hello
I am hitting the ground with my pedals a lot. If i put a lot of air in my tires 28 psi and in the rear shock 20% sag it is not as many hits but it feels very very stiff and bumpy. I prefer 24psi in tire and 25-28% sag and it feels nice to ride except for hitting pedals on ground. Frame has geometry switch but i put in High and feel very forward on the descents.
So my question is, will i be disadvantaged in any way to get shorter cranks? I have 175mm now, maybe switch to 165mm. Will I spin to much and lose power transfer?
I have even tried thinner pedals -Spank Spike.

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When you say hitting on the ground, you mean like strikes on stumps, rocks, etc?

I've had 175, 180, and 170.

I can definitely say at 180, I noticed I was changing my nice pedals off a ton of things and it made pedaling a more "think about crank position" than just get on and ride.

175 I didn't notice it as much, and at 170 I've noticed it's easier to avoid pedal strikes.

I run 170 now, and as far as power, sure the 180s may have put down a TAD more when I stood on the pedals hard, I actually don't feel disadvantaged on climbing or pedaling.

I'm 6' and have a 32 inseam. If you're 6'3 and have a 34 inseam, a 170 might feel weird due to it not seeming like you're getting full range of motion going lower...however my 6'4 buddy got on my bike and didn't notice the length difference at all. I'm willing to bet most people could go 170 without even noticing.

Not sure I'd go 165...that has sounds a bit short, but still might work. But I'd definitely consider changing the crank size, as I doubt you're having a fun ride sagged only 20%...likely only getting 70-75% of suspension travel set up that stiff.

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I had been riding 175 for decades, but new bikes are more prone to pedal strikes and I decided to try 165 on a new bike build. I couldn't tell the difference. Now I am running 165 on all my bikes. A few of my riding pals have tried them too, and all have reported basically the same thing. The only thing we do notice is the reduced pedal strikes.
 

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I am 6 foot with a 34.4 inseam and cannot tell the diff in pedaling 165 or 175-----I also have ridden on the road for decades with 175 so I would be a good candidate to know the diff but I cannot tell unless you told me the cranks were 165.
 

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I should have gone with 170s or even 165s on my last build, instead of 175s, which I have been using for 25+ years. I tried 165s last time in Moab/Fruita and could not notice a difference.

OP - just do it.
 

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All these points are valid and influence pedal strikes...the lower the pedal gets to the ground, the more likely it will hit something. My HT has 175 cranks and my FS has 170...my short legs can feel the difference. I prefer 175 but 170 on FS works better because both ends compress pushing the BB downward. But even so, it is technique that has the most influence for me. I’ve recently noticed I subconsciously alternate my pedal stroke based on the terrain under the bike keeping the pedals away from obstacles while maintaining forward momentum.
 

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hitting pedals on the ground is 99% rider technique and perhaps as much as 1% crank arm length.
For those of us who don't possess perfect riding skills, we have the occasional pedal strike, some pedal bumps, and more pedal grazes. That extra distance can turn many of the strikes into bumps, the bumps into grazes, and the grazes into near misses. And there is the important bonus of reducing the likelihood of the rare but awful full on pedal slam induced ejection. Can you see how that is 100% useful to us mere mortals?
 

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For those of us who don't possess perfect riding skills, we have the occasional pedal strike, some pedal bumps, and more pedal grazes. That extra distance can turn many of the strikes into bumps, the bumps into grazes, and the grazes into near misses. And there is the important bonus of reducing the likelihood of the rare but awful full on pedal slam induced ejection. Can you see how that is 100% useful to us mere mortals?
I hit my pedals on the ground sometimes too. I spent too much time worrying about my bikes BB hieght and drivetrain components before I realized that just like everything else, the issue has more to do with the Archer than the arrow.

Sure. That makes sense. Why not just get some 120mm cranks cranks instead of putting some thought into your riding technique? There's a trade-off and a compromise to be made with every choice in bike builds, and taking every dimension to it's extreme is not going to make up for a lack of skills that any more mortal can acquire of they try. Skill and grace on a bike are not a participation trophy for anyone who has enough money to throw at gear.

Sure, use reasonably thin pedals and don't put 190mm cranks on your bike. That would be silly. Just don't fool yourself into thinking that 5mm shorter cranks (generally not cheap) is going to make anywhere near as much of a difference as paying attention to your technique and becoming more aware of where your feet are at all times.
 

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Sure. That makes sense. Why not just get some 120mm cranks cranks instead of putting some thought into your riding technique? There's a trade-off and a compromise to be made with every choice in bike builds, and taking every dimension to it's extreme is not going to make up for a lack of skills that any more mortal can acquire of they try. Skill and grace on a bike are not a participation trophy for anyone who has enough money to throw at gear.
Im assuming you have never ridden root infested uphill climbs there would require constant ratcheting if it wasnt for adequate BB height? I always have to laugh when people are so quick to dump on someone for riding technique. Ratcheting is great, and Im sure we all use it from time to time, but having to constantly ratchet is a pain in the ass.
 

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Im assuming you have never ridden root infested uphill climbs there would require constant ratcheting if it wasnt for adequate BB height? I always have to laugh when people are so quick to dump on someone for riding technique. Ratcheting is great, and Im sure we all use it from time to time, but having to constantly ratchet is a pain in the ass.
Yes, I ride a singlespeed on rocky central Texas terrain. Much of it is ratchet-or-die, regardless of crank arm length.

I am not trying to dump on anyone, sorry if that came off rude. Just trying to remind everyone that not every problem can be solved with gear. I know several SS who smash local races and use 180mm cranks. It's all skill acquired through time in the saddle.
 

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Yes, I ride a singlespeed on rocky central Texas terrain. Much of it is ratchet-or-die, regardless of crank arm length.
I figured you had likely encountered it as long as you have been around these parts. To each their own I guess. 10mm can make a huge difference IMO. Obviously as you state, its important to learn the ratcheting technique as well.
 

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Wow that went South quickly...lol

I get both sides of that discussion. Yes, technique can make much of the length issue moot. But if someone is relatively new to the sport of MTB riding, is riding in unfamiliar areas, etc, having a few less mm can't hurt.

I stupidly bought some 180mm cranks thinking "oh yeah! better power!" early in the game. In the rooty, narrow rutty areas I ride it became a comedy of errors with a ton of strikes and busted a pedal. I've run 170s since (haven't tried 165 tbh) and I did notice a difference between the two. Also have become a ton more familiar with the topography of my local trails, so that doesn't hurt.

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I sort of agree a lot of it is technique, but technique goes to **** when its 100+ degrees out and you're a couple hours in. Ill take it. I'm going a step further and getting a less saggy rear shock. Debonair cans sag out so far, changing to a normal can is more significant than crank arm length changes, do them both and you're around an inch of added clearance. Thats a lot.

For us shorter guys (im 5'7), short cranks dont have that weird stall out knee angle. I've been riding 170 or 175's for 10+ years, but theres no getting used to it. 165's are closer to being the right length, and I think that matters most.
 

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hitting pedals on the ground is 99% rider technique and perhaps as much as 1% crank arm length.
Agreed 100%. Those that can't tell the difference between 165's and 175's boggle my mind. There are all different types of riders though. Even my wife who is pretty casual tried 165's and was noticeably slower everywhere and immediately went back to 175's just so she could keep up.
 

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Agreed 100%. Those that can't tell the difference between 165's and 175's boggle my mind. There are all different types of riders though. Even my wife who is pretty casual tried 165's and was noticeably slower everywhere and immediately went back to 175's just so she could keep up.
I guess we can agree that there are all different types of riders. I'm not particularly fast or skillful but I have been doing this for roughly a quarter century now so I have things reasonably well figured out for myself and I am a significantly better bike wrench than rider. I spent over 15 years on the same steel hardtail I had built for myself long before I could have anticipated what was to come down the line in bike development, and I kept it well equipped with nice parts over the years.

One thing that never changed was 175mm cranks, and pedal strikes were rare. I have enough technical skills to ratchet around a bit when required. But when I finally jumped an untold number of trends into the future from my old bike and settled on a reasonably modern short travel 29er trail bike, suddenly my pedals were significantly closer to the ground and making contact much more often.

I had read quite a bit about crank length and it didn't seem like there was any compelling reason that 175 was the accepted standard for so long. So I tried a set of 165mm and between the new bike acclimation and all the fun I was having, as boggling as it may be to you, I really only noticed the immediate improvement in ground clearance. Sure my skill could have and would have improved at avoiding frequent strikes, but not having it be such a nuisance was more valuable to me, and I sure can't see what the downside is other than buying new cranks.

Now all the guys I regularly ride with have either made a similar change or are considering it. If anything else is noticeable, I would say that it is easier to increase my cadence, which I don't find to be a bad thing. And I believe that if you care about the math and physics of the change, the rough comparison is to a one size change in chainring, or shifting a single gear. NBD. Everybody should ride what works for them, but crank shaming is completely ridiculous.
 

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I'm going a step further and getting a less saggy rear shock. Debonair cans sag out so far, changing to a normal can is more significant than crank arm length changes, do them both and you're around an inch of added clearance. Thats a lot.
Somewhat of a different problem but definitely related. I ended up changing shocks and it did help a bit with ground clearance, and overall improved the bike even more. Went from a RS Monarch to a McLeod. Bike setup is too involved as a complete system of compatible parts to get too hung up on crank length or any other single issue despite all the debates. Kinda like politics.
 
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