[Closed] Now that Long and Low is a thing should I get 170mm cranks?

I'm running 165mm and not noticed any difference at all, apart from less rock strikes.

Just don't but 170mm raceface Aeffect.

The cranks are no shorter, they have just moved the pedal threads.

I've been on 165mm cranks on the bigger bike for a couple of years now, definitely get fewer pedal strikes, and I've not noticed any adverse effects otherwise.

I have 170 on mine and I still manage to smash myself into pieces pedal striking... But I don't feel any downside of 170 vs 175 (used to have the exact same model on 2 bikes, one was 175 and one was 170,couldn't have told you which was which). 165 felt a wee bit odd, not with pedalling but when in the ready position, my feet felt weirdly close together (even though it's only a few mm it felt like a lot more for some reason)

But shorter cranks need a higher saddle. So they lift the COG up.

I compensated by putting tyre balancing weights in my socks

Nothing wrong with 170mm cranks. On all my bikes and yes they are all quite low by virtue of design or offset bushings.

But shorter cranks need a higher saddle. So they lift the COG up.

You're missing the point of only having the seat at max height on none tech fireroad climbs.

Regardless of seat height, shorter cranks geometrically must mean you are higher off the ground than a longer crank arm.

But seat height is no longer static...

Low BB's feel great on the tech with level cranks when there's no need to pedal.

Shorter cranks allow you to get away with lower BB's when you're forced to pedal.

Dropper posts have changed more than seat height.

I've changed from 175's to 170's on my hardtails and 165's on my full sussers and not noticed any downsides.

“Regardless of seat height, shorter cranks geometrically must mean you are higher off the ground than a longer crank arm.”

Not when your pedals are level!

I like 170s a lot, and I have pretty long (34”) legs. I have 165 on the hardtail and feel like I do notice my foot not sitting as low when the pedal is dropped - but it’s better than the 175s for sure.

How low are we actually talking here?
I am yet to notice any of these new bikes described in reviews and marketing as "long, low and slack" that actually do have very low BBs. some do have fairly big BB drop. but that's only because wheels have gotten bigger.

I have a 33" inseam but have 165s on 6 mountainbikes (hardtails, FS and DH)
I also have 165s on my roadbike.
I don't run 165s for clearance reasons. I run them because I prefer spinning smaller circles.

All my bikes have low BBs. The two lowest are a 200mm DH bike with a 13.5" BB and a 170mm Enduro bike with a 12.75" BB. The 170mm bike is the only mtb I have with 170mm cranks (just because it was a full bike rather than built by me and that's what it was spec'd with).

the DH bike is actually lower at sag and full compression of suspension than the 170mm bike.

I don't have problems with pedal clearance. and I still wouldn't have problems with pedal clearance even if I fitted 175s. folk who constantly hit pedals do it through poor pedal timing, poor technique and poor planning.

You get a low COG from having a low BB. Not crank length. In riding situations where a low COG is advantageous you'll always be stood up.

Anyway. My advice would be to run the crank length you prefer to pedal (which will mean trying various lengths) and try to learn to not drop your pedal into incoming obsticles.

"Not when your pedals are level!"

Crank length won't affect clearance either if your pedals are level.

Best way to avoid pedal strikes on low bikes is to learn to pump more through the rough stuff rather than pedal.

I am yet to notice any of these new bikes described as long,low,slack bikes that actually do have very low BBs. some do have fairly big BB drop. but that’s only because wheels have gotten bigger.

Didn't measured the BB height on my G16 with a 170 crank but found it impossible to ride on rocky trails that felt fine on other bikes with 175 cranks so had to switch to 165's

folk who constantly hit pedals do it through poor pedal timing, poor technique and poor planning.

No it really wasn't. It was a case of not being able to pedal when I really needed to..

Best way to avoid pedal strikes on low bikes is to learn to pump more through the rough stuff rather than pedal.

Love to see you pump uphill on a rocky trail for more than 10 foot.😜

“Crank length won’t affect clearance either if your pedals are level.”

Who hits their pedals on the ground when the cranks are level?!

One of my bikes has adjustable geometry. When I raise it from low to neutral (+6mm BB height) it makes a big difference in the ease of getting up technical climbs due to being able to get full pedal strokes in without smacking pedals on the ground. That’s with 170mm cranks.

When my 27.5 hardtail was running a shorter fork and angleset it had 55mm BB drop and with 175mm cranks it was a nightmare on flatter trails. I like pumping but sometimes you need to pedal!

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"Brant wrote,

Regardless of seat height, shorter cranks geometrically must mean you are higher off the ground than a longer crank arm."

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Unless you have some of those newfangled "knees" the kids are all going crazy over. When you're not plonked on the seat your body's COG is where you put it not where the pedals want it to be.

No it really wasn’t. It was a case of not being able to pedal when I really needed to..

Yes. Like I said.  poor pedal timing, poor technique and poor planning.

If you want to sit on your bike just point it at things and pedal that's your choice. But sorry you can't really blame hitting your pedal off things on anything other than your own poor judgement.

Yes. Like I said.  poor pedal timing, poor technique and poor planning.

😁 You going to enlighten us all on how you pump uphill for 10' or more then.

The G16 is an awsome bike but in the low setting with 170 cranks on it kind of struggles on tech rocky climbs.

No dought you'd be able to plan your way up without pedaling though.😂

I didn't mention pumping at all. some other guy did.

I'm not really interested in arguing with you. but what I will say is this. Assessing the terrain ahead, working out grip, line, approach speed, gearing, how, when and how much of a pedal stroke you are able to put in to maintain momentum but not clip a pedal is a skill. A skill required whether you have a 10" BB height or a 14" BB height. Granted. you have to pay more attention and work harder at figuring it out with the 10" BB. You obviously don't get on with low BB heights. and that's fine. But please don't say the current standard of low BB bikes (which as I already said aren't all that low in the first place) can't be ridden up rough terrain. it's just more difficult if you're not used to it.

Unless you went full custom geometry. (in which case I'd expect you to remember your BB height) Those Geometron bikes aren't all that low.

I’m not really interested in arguing with you.

Seems otherwise to me.

Never really had any problems on the same trail on any of my other bikes. Including a 29er frame running B+ wheels.

 You obviously don’t get on with low BB heights.

Thing is though I really do with 165 cranks on.

Thanks for your analysis of my riding though. That's quite a skill you have there being able to judge someone without ever seeing them ride or even knowing what they were trying to ride.

I'll leave you to it though as you'll obviously not let it rest until you've had the last word....

GW, have you considered writing down your usernames and passwords somewhere, so you don’t have to open a new account here every few months?

Chief.

Thanks for confirming my suspicions.

If I'd realised earlier I'd have just ignored him.

When I had my Smuggler (which was too low for my liking) what drove me mad was trying to ride ruts. Plenty of natural trails have sections worn away by walkers that are narrower than the width of mt pedals and deep enough that I kept catching them.

I have a theory (probably rubbish) that low BBs are an attempt to compensate for chainstays that are too short. You could get the same stability with longer chainstays and a higher BB without bashing your pedals all the time.

But shorter cranks need a higher saddle. So they lift the COG up.

Even if I'm not seated and my cranks are level?

Damnit! Late to this party, have my 175's just gone obsolete?

Im still going to wait till LLS™ bikes straddle 2 continents and the BB shell hits the earth's iron core before upgrading though. 😊

Climbing off road

https://singletrackmag.com/forum/topic/crank-length-9/

Whether a high bottom bracket or low bottom bracket the tyres contact the ground at ground level.

https://crosscountrycycle.wordpress.com/2016/12/02/repetition-makes-truth/

I switched because i felt too stretched out on 175 mm. I find on 165 mm i feel more stable, cornering is better. I was surprised how much difference a few mm can make. I have always assumed longer cranks were better but when i think about it i have no idea why i came to that conclusion. It annoying that is quite an expensive dimension to play about with.

Love a good STW geometry discussion

paton.

What length cranks for hopping instead of pedaling? 😜

Maybe a certain bike brand will cone up with dropper cranks. That would see a 175mm arm go down to 160mm for when folk can’t adjust their technique according to trail being ridden.

YES YOU HEARD THAT HERE FIRST! 😂

although having bought one of these new slack low but shortish bikes, I have encountered more pedal strikes in 1 ride than years gone by on other varying bikes of hardtail and full suss.

Your dropper crank company will go bust when I launch my elliptic cranks, 175mm when horizontal and 165mm when vertical. Matched with an oval ring they will give a 33% speed boost

for what it's worth I swapped 175 cranks to 165 on my scout and it's been 100% positive so far.

D’oh meant to say that and that you can buy the Patent from me in 40yrs time. Muhahaha!

Imagine self adjusting electronic slack head sets for varying terrains that auto change head angle.

Is this how the magic roundabout creators felt when they were high

As you have a choice of gears then shortening the cranks is not an issue as you can just use lower gear with higher RPM (possible with shorter crank arm).

The shorter the cranks the lower the gear the higher the RPM

swapped between 165 and 170 cranks and see no difference in pedal strikes.  165 cranks not and good as 170 for pedaling.  wouldn't go back to them.

The advantages of a low BB aren't really aimed at climbing ability, and in some circumstances they're going to hinder it (like my 26" bikes with lowish BB's) In these circumstances a slightly shorter crank might just help, and anything that makes climbing less of a chore is a bonus. You can't pump a climb, sometimes you cant even backpedal 1/4 of a turn to miss clipping something.

There might be marginal improvements when your pedals are "level" (there's usually at least one pedal dropped a bit in any situation) and there's plenty of corners where you'll need you outside pedal right down and still use a fair bit of travel.

Overall I'm convinced that there are benefits of 170 and 165 cranks on some bikes.