153 mm cranks

wepn

The Barking Owl ?
Jul 18, 2019
1,006
1,145
AU
I think you chose the right length. Which ones are they? I have 140's on at the moment but they're too short. I hope my Miranda Kappa O 155's arrive soon.

5.jpg


Screen Shot 2019-08-25 at 12.31.27 pm.png
 

33red

New Member
Jun 12, 2019
447
137
Quebec, Canada
Are they called square? My Haibike came with 175, after 2 months i switched to 165, now i look for 155 kind of a rare thing around Quebec, Canada. My system is Yamaha so i am not sure if they would fit?
 

Zimmerframe

MUPPET
Subscriber
Jun 12, 2019
13,954
20,691
Brittany, France
Are they called square? My Haibike came with 175, after 2 months i switched to 165, now i look for 155 kind of a rare thing around Quebec, Canada. My system is Yamaha so i am not sure if they would fit?
Nope. They're ISIS fittings. You need tapered square ones.

Something like these maybe :

square taper cranks 150mm | eBay
 
Last edited:

Moss

Member
Oct 8, 2018
10
11
Ireland

steve_sordy

Wedding Crasher
Nov 5, 2018
8,771
9,064
Lincolnshire, UK
On another Forum someone was asking why BB height varied so much from bike to bike. He got the usual answers about the difference between DH bikes and XC bikes, the amount of suspension travel etc. But then someone said that if you assume that the bike is sagged by 30% the BB will drop by 30% of the travel on a FS and by about one third of that on an HT (positioning of the BB horizontally between axles). Surprisingly, the heights of all the BB centrelines looked at (big travel, small travel, FS and HT) came out at 290mm give or take a bit. By all means check your bike, but don't crucify me if you come back with 285. :)

Is there a design parameter here that the bike designers use, ie aim for 290mm and if its less, shorten the crank by that amount (again give or take).

I suppose that the real parameter is the height of the lower pedal axis. Therefore on a nominally standard 170mm crank length, the pedal axle height would be 120mm. On my Focus Jam 2 29er, my 30% sagged BB height is 285 and my crank length is 165, ie axle height is 120mm! :LOL:
Designers have to target something, even if its just a rule of thumb, or something the industry knows "just works!"

Anyone else? Or are you all bored to tears by now? :giggle:

If this is true, and all designers are targeting 120mm, then all the chatter about needing shorter and shorter cranks because it's an emtb, is just that; chatter! :love:
 

33red

New Member
Jun 12, 2019
447
137
Quebec, Canada
On another Forum someone was asking why BB height varied so much from bike to bike. He got the usual answers about the difference between DH bikes and XC bikes, the amount of suspension travel etc. But then someone said that if you assume that the bike is sagged by 30% the BB will drop by 30% of the travel on a FS and by about one third of that on an HT (positioning of the BB horizontally between axles). Surprisingly, the heights of all the BB centrelines looked at (big travel, small travel, FS and HT) came out at 290mm give or take a bit. By all means check your bike, but don't crucify me if you come back with 285. :)

Is there a design parameter here that the bike designers use, ie aim for 290mm and if its less, shorten the crank by that amount (again give or take).

I suppose that the real parameter is the height of the lower pedal axis. Therefore on a nominally standard 170mm crank length, the pedal axle height would be 120mm. On my Focus Jam 2 29er, my 30% sagged BB height is 285 and my crank length is 165, ie axle height is 120mm! :LOL:
Designers have to target something, even if its just a rule of thumb, or something the industry knows "just works!"

Anyone else? Or are you all bored to tears by now? :giggle:

If this is true, and all designers are targeting 120mm, then all the chatter about needing shorter and shorter cranks because it's an emtb, is just that; chatter! :love:
I might be wrong master Steve but i think many Ebikes have a BB a bit lower and i compared mine to a bike a bit wider arm to arm. These 2 factors might generate more pedal strikes. The lower BB is to keep the added weight less obvious. Also some systems have a delay in the assist so the rachet technique might be less effective. Maybe with the added speed we tend to look more at a distance and i can say my 175 stock were a pain.
 

Dee Scee

Member
Dec 21, 2018
192
98
Berkeley
i just received my 160mm from berkshire delivered to california. thanks berkshire cycles!!! my large 2017 levo has 170mm so, my mod is relatively conservative. im still a little nervous about 152’s... even with the reassurances i’ve read here. frikkin @Kiwi in Wales loves his 135’s i think? ? i will share my feedback when i get these mounted and grt a few rides in for sure. also mine are branded KTM also. kick that mutha!!!
 

steve_sordy

Wedding Crasher
Nov 5, 2018
8,771
9,064
Lincolnshire, UK
I might be wrong master Steve but i think many Ebikes have a BB a bit lower and i compared mine to a bike a bit wider arm to arm. These 2 factors might generate more pedal strikes. The lower BB is to keep the added weight less obvious. Also some systems have a delay in the assist so the rachet technique might be less effective. Maybe with the added speed we tend to look more at a distance and i can say my 175 stock were a pain.

That they may! I also don't know. (By the way I am no master at anything now I'm no longer working). :LOL:
I took the BB height for my Focus from the geometry page and went from there. It had a BB height noted as "-20 mm", ie 20 mm below wheel axle height. As I said the pedal axis height came out with the same figures as for the clockwork bikes I mentioned. I was curious that's all.
As for the Q factor, I sort of remember a thread on here that it wasn't much different to non-emtbs, but I accept that small differences add up.
 

Kiwi in Wales

Short cranks rule!🏴󠁧󠁢󠁷󠁬󠁳󠁿
Patreon
Founding Member
Jan 24, 2018
1,241
1,589
Carmarthen, Wales
i just received my 160mm from berkshire delivered to california. thanks berkshire cycles!!! my large 2017 levo has 170mm so, my mod is relatively conservative. im still a little nervous about 152’s... even with the reassurances i’ve read here. frikkin @Kiwi in Wales loves his 135’s i think? ? i will share my feedback when i get these mounted and grt a few rides in for sure. also mine are branded KTM also. kick that mutha!!!
;) Yeh, still loving them (y) they are 140mm now as the 137’s I did have on had a wider Q factor. I thought I would try something narrower and these have been brilliant. Probably done around 1000kms on them so far and still happy with then.
Please remember all, I have these on due to the very steep terrain I have where I ride. Very tight, steep, rutty, lumpy, natural, single track where you have to continuously pedal otherwise you stall and fall. I still fall or dab, but not due to pedal strike anymore ;)
 
Last edited:

Mcharza

E*POWAH BOSS
Aug 10, 2018
2,581
5,176
Helsinki, Finland
;) Yeh, still loving them (y) they are 140mm now as the 138’s I did have on had a wider Q factor. I thought I would try something narrower and these have been brilliant. Probably done around 1000kms on them so far and still happy with then.
Please remember all, I have these on due to the very steep terrain I have where I ride. Very tight, steep, rutty, lumpy, natural, single track where you have to continuously pedal otherwise you stall and fall. I still fall or dab, but not due to pedal strike anymore ;)
What is the right Q factor? Q4/Q8 ?
 

Kiwi in Wales

Short cranks rule!🏴󠁧󠁢󠁷󠁬󠁳󠁿
Patreon
Founding Member
Jan 24, 2018
1,241
1,589
Carmarthen, Wales
So you mean, if you're ex-cowboy you need bigger q factor ;)
Not sure of what is q4 q8 etc....
However, the current 140mm cranks I have on have a ‘roughly’ measured Q factor of 170mm.
The 138mm cranks have a ‘roughly’ measured Q factor of 194mm.

Obviously the diagram below is not of an ebike.

A512F541-89CF-410B-986A-8D22431FEB16.jpeg
 

Zimmerframe

MUPPET
Subscriber
Jun 12, 2019
13,954
20,691
Brittany, France
I think if you search for levo cranks and maybe limit it to posts by rob, you'll find the original thread where he talks about these and the Q factor he bought (4,8,16)- and the spacing that gives and what Q factors would fit/work ..
 

Tim69

Well-known member
Feb 25, 2019
180
210
Israel
The Q factor is actually the amount of offset of the crank arm itself. The distance from the surface of the crank bolts to the surface of the pedal hole.
I checked it on my kenevo, and yes it's 4,8.
Also the Miranda site offers a special set of cranks for the Specialized Levo/Kenevo That is specifically with a Q factor of 4,8.
You can see all the info in this thread;
" shorter cranks arms for Levo/kenevo"
Tim
 

EMTB Forums

Since 2018

The World's largest electric mountain bike community.

545K
Messages
27,460
Members
Join Our Community

Latest articles


Top