Crank length change .

[BMXER]

I stopped worring about crank length and focused on actually riding, now I am 3km faster per hour and focus on power.

Your wife won't notice 2.5mm, neither will you unless you are built like a cartoon character and in the WAY tall or WAY short hurd. Now get out and ride!

Edited March 24, 2021 by BMXER

[Headshot]

To all the people claiming the shorter crank gives you less pedal strikes you are wrong. You should adjust your style of riding. I have just done 2 hours on Tokai riding over the big rocks and logs. I didn't have a single issue. Crank 175.

You're probably right. On a long travel bike however, with lots of squish at the back, a shorter crank may help a little. I almost never get pedal strikes on my 175 cranks on my HT but get a few on my enduro bike - poor technique is part of it, but the risk is increased on a 170 rear travel bike. 

[patches]

To all the people claiming the shorter crank gives you less pedal strikes you are wrong. You should adjust your style of riding. I have just done 2 hours on Tokai riding over the big rocks and logs. I didn't have a single issue. Crank 175.

 

How do you figure that?

 

It's like saying wider bars don't increase the chance of clipping trees. If one object has larger dimensions than another it it surely has more surface area and reach for potential clash with its surrounds. It's physics isn't it.

 

I also guess you should tell Greg Minnaar (170mm cranks for a 1.88m rider) and Sam Hill (known to use 165mm cranks) that they are wrong and need to adjust their riding technique?

 

Perhaps if Sam improved his riding technique he wouldn't have need for protective crank boots, and his pedals wouldn't be so scuffed and scraped. He'd probably save money on replacing pedal pins too! 

 

 

...but my facetiousness aside    you are correct in saying that technique has a lot to do with it. Many of the component based benefits we have on bikes could be overcome by improved technique.  However as riders push the[ier] limits they will find a spot where their technique runs out and their equipment could make the difference between thrills or spills.

 

Also as Headshot points out below, when a longer travel bike bottoms out, it gets pretty close to the ground. I ride a Trek Remedy (160mm F/ 150R) . It has a BB height of 349mm (under no load). The BB drops to 338 when suspension just at regular sag settings. 175mm cranks then give a ground clearance of 163mm. That's not very much so an extra 10mm on that is appreciated.

 

When bottomed out it gets even hairier and the risk of pedal strike becomes a very real threat, anywhere in this sorta region

 

 

You're probably right. On a long travel bike however, with lots of squish at the back, a shorter crank may help a little. I almost never get pedal strikes on my 175 cranks on my HT but get a few on my enduro bike - poor technique is part of it, but the risk is increased on a 170 rear travel bike. 

[patches]

Here are a couple of articles advocating shorter crank lengths for MTB. 

 

https://www.redbull.com/nz-en/how-long-should-mtb-cranks-be

 

https://fitwerx.com/mountain-bike-crank-length-likely-long/

[Grease_Monkey]

To all the people claiming the shorter crank gives you less pedal strikes you are wrong. You should adjust your style of riding. I have just done 2 hours on Tokai riding over the big rocks and logs. I didn't have a single issue. Crank 175.

Depends on the bike. Newer mtbs are designed with lower bb height, so if you don't change something you get more rock strikes - especially on longer travel bikes. When I first got on my stupidly long and low Transition Sentinel with 175mm cranks I was getting alot of rock strikes compared to the my other bikes. I ended up bending the crank arm (unrelated), so when I had to replace I went 170mm, much better on that bike. Also better coz I have short legs, but that has nothing to do with the rock strike argument.

 

Like pretty much everything on a bike, crank length can't be looked at in isolation.

[DieselnDust]

Most DH bikes I see and even Enduro and trail bikes have shorter cranks than XC bikes.

As pointed out th bb on those bikes are lower and sagged the bb's are only slightly higher  than XC bikes.

Sagged condition also results in lower bb' for similar travel bikes based on the leverage ratio of the rear suspension. E.g. a Scott Spark has a lower BB under recommended sag than a Scalpel Si (2017-2020). Its a few mm difference but those mm make a difference between pedaling through a rock garden vs picking the timing of your pedal strokes

[Grease_Monkey]

As everyone is welcome to their opinion I will stick with mine. For sure if you look hard enough you will find pros and cons. This is the way it works. If your pedal stroke is down on either side while riding through a rock garden or any other kind of obstacle you are likely to hit it. Better riders will have less strikes. If you are telling me that by having a 170mm crank over a 175mm crank eliminates pedal strikes I would disagree with you. Again my opinion. I would certainly not change my 175 as I mainly do long touring.

 

And also clearly not open to your opinion being changed when presented with very logical facts. 5mm is 5mm, sometimes that is all it takes to clear a rock in a trail. I would argue most people try not to hit the rock on the trail in front of them, so when they do hit it, it's not like they are off by a long shot, they are probably only off by a few mm where a shorter crank would help - yes skill would too - but if we apply that logic to everything we should all go back to rigid bikes with 500mm wide stems. 

 

Just for context though, I've never (not that I can remember) had a rock strike going down, only up on techy rocky climbs on a long travel bike. The types of climbs where you have to keep the momentum going and timing your strokes perfectly is not always possible - not for me anyway. 

 

As for the touring thing - the biggest advantage I found with shorter cranks was actually the comfort when pedaling longer distances. Not so much that I would go and swop a perfectly good 175mm crank for a 170mm - but enough that when I buy new I would go for a 170mm option - but I have already posted about that further up in the thread so I won't get into that again.

[ChrisF]

Most DH bikes I see and even Enduro and trail bikes have shorter cranks than XC bikes.

As pointed out th bb on those bikes are lower and sagged the bb's are only slightly higher than XC bikes.

Sagged condition also results in lower bb' for similar travel bikes based on the leverage ratio of the rear suspension. E.g. a Scott Spark has a lower BB under recommended sag than a Scalpel Si (2017-2020). Its a few mm difference but those mm make a difference between pedaling through a rock garden vs picking the timing of your pedal strokes

Going from the Trek to the Scott Spark I suffered pedal strikes for the first couple of rides ....

 

That lower bb required a rider adjustment ... or shorter cranks.

 

 

For my mild routes a rider adjustment got rid of 99% of rock strikes.

 

But I would understand if some needed shorter cranks on this bike.

[SwissVan]

I’ve mostly used 175 cranks, once I had a custom road frame built in SA and the BB height was to low by a few mm, i was always hitting my pedals in corners.... the guy who built it ended up building a new one under warranty.

[Mike Mac]

To all the people claiming the shorter crank gives you less pedal strikes you are wrong. You should adjust your style of riding. I have just done 2 hours on Tokai riding over the big rocks and logs. I didn't have a single issue. Crank 175.

Can you perhaps share some tips on how to adjust style to avoid peddle strikes. I get a strike on most uphill technical sections and would love to learn how to avoid them.

[SwissVan]

Can you perhaps share some tips on how to adjust style to avoid peddle strikes. I get a strike on most uphill technical sections and would love to learn how to avoid them.

Look ahead and choose your route appropriately, after a few pedal strikes you should be able to judge where it’s likely to happen and time your pedaling to avoid strikes

[DieselnDust]

I'd like to think I dont have many Crank arm strikes but when I look at the damage to my Crank boots and even on older alloy cranks, I'm grazing a lot of rocks.

So ifaa shorter Crank is biomechanically better as well as allowing me to ride a little more confidently and aggressively through rocky terrain then it's an advantage I want

[Mike Mac]

SwissVan has put most of it into words. I never said I have never had a pedal strike. However if you are riding around and it is happening to you all the time, (in my opinion) shorter cranks will not help you. Go get some riding lessons. I am not a coach. It does happen. I never said anything to suggest otherwise. I also said I personally will not change my crank length. The heading and thread is simple. My opinion is a simple one too. Like it... don't like it... I don't care. My point was if you are riding around hitting your crank arms quite frequently then you should probably learn how to try and avoid obstacles.

I wasn't trying to be funny or challenge your opinion. I was genuinely enquiring what techniques you have learnt that reduce peddle strikes, which has been now been answered as "looking ahead" and "timing ones peddle strokes".

 

I will focus on those aspects and see if I can improve the number of strikes I get on the technical up hills.  

 

Thank you.

[DieselnDust]

I wasn't trying to be funny or challenge your opinion. I was genuinely enquiring what techniques you have learnt that reduce peddle strikes, which has been now been answered as "looking ahead" and "timing ones peddle strokes".

 

I will focus on those aspects and see if I can improve the number of strikes I get on the technical up hills.  

 

Thank you.

 

 

 

To manage peddles strikes I use "trucaller"

To manage pedal strikes I use timing and list (leaning the bike over)

[Mike Mac]

To manage peddles strikes I use "trucaller"

To manage pedal strikes I use timing and list (leaning the bike over)

 

Thanks

[ChrisF]

...

 

 

 

I will focus on those aspects and see if I can improve the number of strikes I get on the technical up hills.

 

Thank you.

Mike on most trails it is easy enough to look ahead, and the odd back pedal to avoid pedal strikes.

 

True technical uphills are a different beast !!

 

There is one forest section along our trails with tight turns, then short steep inclines, add in big roots ....

 

You need to keep pedaling to keep momentum, the rear wheel breaks away on the loose surface .... not that easy avoiding pedal strikes under these conditions (not for an average rider like me) ....

 

But it still comes down to rider skill, and looking ahead ....

 

Hang in there