Crank length/bb height . Is shorter/lower the future?

Not for us tall people.

Where are you even getting 145’s?

I mulleted my Propain Tyee and run 145 5DEVs on it. I'm just over 6ft and absolutely love them. For a while my legs hurt as new muscles were called into action, but now it just feels fantastic. I do DH runs with my bike as well as 50 mile rides.

I'm 5'8" and have been on the conservative side of short for about a year - 165. Previously on 175 my entire biking life (~20 years, I'm 34 just so we have all the metrics out there).

After about a month, I got 165s for my gravel bike, too. I'd love to try 155s but it's not in the budget right now and I love the 165s. After a year, I've noticed numerous benefits that I'm confident are no placebo at this point. Mtb-wise, this year has been spent on the same bike and parts: Banshee Rune V3 w/same drivetrain, pedals, seat, seat-height, dropper, handlebar (minor changes in sweep/spacers), even the same grips. Some parts replaced for wear, obviously.

Benefit wise, and beyond the obvious like decreased pedal strikes, etc., my hip flexors get less sore (a chronic issue for me), possibly from less over-extending; my butt/inside of thighs get less sore when stacking big days in the saddle; less back & neck pain, but that's less noticeable. Maybe the best improvement is my positioning on the bike. Shorter cranks seem to make a wide handlebar feel better or more manageable, at least for my t-rex arms. And I really like a wide bar (760mm, again 5'8" here) for the dangerous stuff. During cornering, I find it easier to point my knees and hips with my feet a little closer together. Similarly, it's easier to drop my heels and coordinate the degree to which I do. All in all, I feel less spread out on the bike, which is really nice with longer wheelbases these days. Anyway, I'm sure I could think of other improvements, but I'm two beers in and those are what come quickly to mind. I'm not sure I'd say any are drastic changes, but all together it's made biking more enjoyable.

And I guess to get back to the point, I've run the Banshee in the low setting ever since, while previously alternating between the two for different terrain.

I've found that I prefer a higher BB than what is fashionable after a couple scary rock strike while descending. I also find that I prefer cornering with the higher BB and don't notice a downside while riding. I prefer to mullet my bikes by going with a bigger front tire rather than switching to a smaller rear. That said, I'm a little guy and have always appreciated shorter cranks 165/170. I've definitely wanted to try some these newer extra short options. 

I'm preferring shorter cranks - but independent of BB height. The BB doesn't need to be crazy low, and it depends on the rest of the proportions but I think a lot of the reasons people wanted low BB's is from when bikes were super short and they would feel tippy otherwise.

Stoked on the feedback here.  I grabbed some of those 145mm 5devs to try a few months ago, now that our endless winter is over I need to give them a try.  I’ve been on 165s for years for most of my bikes.  

One downside I find with lower BBs is that it’s harder to lift the front wheel (manuals etc. but maybe that’s because I’m not good at them in the first place…) Downside of shorter cranks I find mostly that most manufacturers don’t offer anything below 165mm. Would love to try 155 but not at 5dev prices…

Canfield makes cranks down to 150mm I believe - they’re a cheaper option at $200.

I'm mostly riding e-mtb for what it's worth, but I love short cranks down to 150mm after a few years on 155mm. Absolutely hate low BBs, I do not feel any improvement in cornering, but hitting pedals/cranks and sometimes even the downtube is a horrendous feeling and I have had very bad crashes from it.

So I'm ok with manufacturers speccing shorter cranks, but please keep the BB's up around 350mm for enduro bikes, or have flip chips that allow for proper changes.

If marketing guys from big dogs decide short cranks are the latest and greatest, most people will follow. As with everything. If they won't, most people will stick with 170-175 because that's what we used to run back in the stone age of mtb, so it must be right. Screw biomechanics and similar mumbo jumbo.

It becoming the oem norm will depend if the benefits can be sold in a simple way to convince the average joe, logic usually results in the concensus of longer = more power but with recent sceintific studies suggesting shorter doesn't reduce power (within a range anyway) then i can see that convincing people, as usual the botique brands will go first then if enough people demand it the big boys will follow, i like the idea of using it to get the BB lower, lower COM is good, less rock strikes is good and i'd say feet position closer to level is good too (MX bikes don't stagger foot pegs for a reason), just non of it is worth sacraficing the little power i have, but if it doesn't sacrafice power i'm all in.

Is there a limit to BB height beyond crank length though? how short can you go before the limiting factor to bb height is hitting your chainring or BB shell off terrain when rolling over obstacles, i tend to avoid pedal strikes by timing my pedal strokes around obstables but you can't do that with a chainring and there's definitely times my chainring is close to stuff already, hence bash guards exist, more testing is probably needed but will be interesting to see if 10-15mm shorter cranks can result in a similar BB drop.

The limit for BB drop will probably be bikes sucking to ride. Lower BBs effectively give you more stability, but you don't necessarily want an abundance of stability on a bike where you want to be able to change direction quickly.

It's also worth bearing in mind that while shorter cranks give you more clearance in terms of when you're rotating the cranks, they don't do much to help with clearance either in tighter areas (e.g. ruts) or when you're leaning your bike over. If you drop your BB by 15mm because your cranks are 15mm shorter, unless you're going to somehow reduce your Q-factor/offset you're still going to encounter more strikes, just from a different direction.

You guys are crazy running 145 5Dev cranks. It says right in the description 135-145 are intended for youth bikes. 
 

Ive been running 160mm 5Dev (would not have been my first choice but due to lack of options) on my Gnarvana for a couple months now and absolutely love the length. They feel better standing and way less pedal strikes. 
 

 I’d be pre-ordering NSB cranks if i didn’t already have these 5dev’s. I’ve had a bad taste for bougie parts lately. I bought a pair of Crue pedals a while back and while they are the most comfortable pedal my feet have ever touched the maintenance is unacceptable. They require cleaning/regreasing after every other ride of they creak/click. Guess it will give me a good opportunity to inspect the cranks on a regular basis. 

It's true, they asked to see my ID when I bought mine to prove I'm 13 or younger haha. Jokes aside,  I just don't feel or see a downside. I even went up to a 34t chainring on a 10-50t cassette. I love AZ'e techy climbs and it just works out here

I think the inference is more that they aren't going to be as strong as their longer cranks. Every time I've seen a brand specify that cranks either have a weight limit or are recommended for 'younger riders', that's code for 'strength concerns'. 

I'm not sure what would cause it to be the case with those cranks vs. their longer cranks, but it could be something as simple as where the pedal broaching is in relation to the cut-outs on the cranks or the thickness of the cranks at that point compared to their other cranks. If there wasn't a possible issue with them, they wouldn't be actively trying to limit possible users, especially as going for short cranks is very much in vogue at the moment.

Considering the amount of snapped/cracked 5Dev cranks you can see floating around online, I'm not sure I'd want to roll the dice with some that even the brand themselves are inferring are going to be weaker than their 'grown up' cranks. That said, I'm also not convinced by the shift to 100% CNC'd cranks in general (forged then CNC'd cranks will be stronger, and are the better but more expensive way to make cranks), so that would rule me out of them from the get-go, let alone the giant cut-outs...

5’11” (lotta leg) and am on 160s which are ok but I find a lot of loss in leverage. However FAR less pedal/crank strikes, kinda gotta decide for yourself what is more worth it to you. Remember for 5 DEV that their crank arms are 5mm shorter at the end or more than most other crank brands .

For people who actually go very very short <150mm, do you go down heaps in chainring size to match, like minus 4 or 6 teeth? I experimented with 160s after riding 170s and felt like I immediately had to drop down 2t, which is no bad thing for ground clearance or weight. Seems like an overall win for ride feel, rollover, and weight reduction.

Another question for those that have gone very short: Do you raise the seat by the difference in length? Like so when pedal is down, your knee angle is the same as it was with longer cranks? 

With manufacturers pushing into designed-for-kids bikes there's a fresh batch of solid and cheap cranks coming out. Outside of the everlasting Canfield Brothers both the Praxis Zane ($160) and Trailcraft Direct Mount Cranks ($170) are really good new options.

As for seat length, I raise it by the difference so my leg is hitting the same angle at bottom-of-stroke. This would seem to also call for raising the cockpit by the same amount, but I haven't felt the need to do so. Given that my leg isn't as bent at top-of-stroke, it might be giving my back more freedom.

The only annoyance I've encountered so far is that my seatpost height at dropped position is a bit higher. I'm contemplating swapping to a longer dropper to remedy this, but that's a bit more expensive.

Definitely. I have a 180mm dropper (6'3) and others with limited insertion depth may have the same issue related to reduced clearance. For those with long droppers and crazy good standover clearance it's a non-issue.

At 5'6" I've always been curious of shorter cranks.  I have 3 bikes with three different sizes, 165 (freeride), 170 (all mountain), 175 (hardtail).  I enjoy the 165s and have wanted to try 155s for a while.  

Can we post who is making shorter cranks? 

Canfield - 150-165mm (5cm increments) https://canfieldbikes.com/collections/cranks-chainrings/products/canfie…

North Shore Billet - 155-170 (5cm increments) https://northshorebillet.com/collections/drivetrain-components/products…

Hope - 155, 160-170 https://www.hopetech.com/products/drivetrain/cranksets/evo-crankset/

5Dev - 135-165 (5cm) https://5dev.com/collections/cranks/products/new-crank-product-page?var…;

Am I missing any others? 

As I posted (not entirely appropriately I may add) on another thread, absolutely. I had been on 170s for a long time until I got my Trance X, which sits considerably lower than the SB66 it replaced. Stock cranks were 170s and after numerous rock strikes, one involving me wondering if I broke a toe, I decided to swap to shorter Canfield 155s. A bit odd at first, but it took less than 20mi to figure out the new feel. My cadence is more consistent, punchy climbs feel like there's more traction available since I'm spinning rather than punching the pedals, shifting is decidedly smoother from the higher cadence, and of course, rockstrikes have all but gone away. Unintended bonus, I found it easier to stand up to jumps/square off trannies, which makes taking things upwards more comfortable. I did have to raise the post about 15mm to compensate for the length change, but I haven't really found a downside to that other than I am considering a longer dropper at some point. In the end, I liked it so much I swapped out the cranks on my hardtail and switched to 165s on my Wolverine. Canfield was ahead of the curve on this one, having a great article on their website at one point about why shorter cranks make sense, and part of that was with them dropping BB heights well before the rest of the industry caught on. 

That's true for some cranks from some manufacturers. From memory, the SRAM GX cranks I had were essentially the same basic crank, but the pedal broaching was drilled in a different place. I had 175s on one of my bikes and got a set of 170s for another, and the overall crank arm length was the same but the pedal was in a different place.

In contrast, my RaceFace cranks were made so the overall crank length reduced to suit the crank length. The 165s I've got on my bike now have minimal overlap, so give great clearance compared to the SRAMs I had before.

I would imagine most CNC-only cranks will have minimal overlap too as they're not constrained by having to work with a forged blank that they're machining from.

For many years I followed the internet rule of long legs (36 inseam), long cranks (180). I always had tons of pedal strikes and lacked confidence for nearly 20 years. I watched a video at Hardtail party on crank lengths and decided to try something different. I now run 165 on my singlespeed hardtail and have no pedal strikes or perceived loss of power. Considering 155 or 160 on my YT Izzo and flipping chip to drop.

Considering the stuff floating around with 5devs breaking, I’d be skeptical at the least. I’m on 160mm 5devs and will be keeping an eye on mine. 

at 6 ft, i cant run less than 170, i've tried many lengths but they push my feet together so much it feels like im standing high on the bike which gives that "top heavy" feeling
- i know how to pedal so i dont have pedal strikes  when going up, Ive only hit my pedals twice in the whole time ive done MTB, both were on big flat pedals and i had my feet in wrong spot.
Never hit them on clips.

I don't think I'm on the internet enough to have seen that, but thanks for letting me know. I'll be on the lookout too!