Quantcast

Random new bike thread

HardtailHack

used an iron once
Jan 20, 2009
3,068
802
13.75"/13.5" bb height. does that really require 165mm crank arms?
Is there any other length? Why do 175mm cranks still exist if people have 2:1 reduction in first gear?
Surely the torque argument is redundant nowadays.
Have you heard about the benefits of bladed spokes?
 

Westy

the teste
Nov 22, 2002
44,166
9,888
Sleazattle
have you heard about ergonomics?

There are a bunch of different formulas out there for picking the correct length of crank for power output and ergonomics. You will find that unless you are over 7' tall that the 175mm crank doesn't make sense for most people. Like geometry 30+ years ago the bike industry selected the best road bike standard available at the time for offroad use. In this case the best crank length for the available gear ratios. lack of gear ratio stopped being a problem a long time ago and like geometry people are finally starting to look at what is best for actual mountain biking.
 

jonKranked

Press Button, Receive Stupid
Nov 10, 2005
69,634
12,566
media blackout
There are a bunch of different formulas out there for picking the correct length of crank for power output and ergonomics. You will find that unless you are over 7' tall that the 175mm crank doesn't make sense for most people. Like geometry 30+ years ago the bike industry selected the best road bike standard available at the time for offroad use. In this case the best crank length for the available gear ratios. lack of gear ratio stopped being a problem a long time ago and like geometry people are finally starting to look at what is best for actual mountain biking.
i did a quick google for crank length formulas. i randomly picked the first two that came up that were different. one yielded 175mm cranks. the other yielded 180mm. to be fair these were based on quick measurements with a tape measure by myself.
 

Westy

the teste
Nov 22, 2002
44,166
9,888
Sleazattle
i did a quick google for crank length formulas. i randomly picked the first two that came up that were different. one yielded 175mm cranks. the other yielded 180mm. to be fair these were based on quick measurements with a tape measure by myself.
What is your source? I am guessing you are looking at "traditional what MTB cranks should I use" vs "what cranks should I use for power output, efficiency and knee health"
 

jonKranked

Press Button, Receive Stupid
Nov 10, 2005
69,634
12,566
media blackout
What is your source? I am guessing you are looking at "traditional what MTB cranks should I use" vs "what cranks should I use for power output, efficiency and knee health"
i just googled "bike crank length claculator"



if you have a better formula i'll gladly try it.
 

Westy

the teste
Nov 22, 2002
44,166
9,888
Sleazattle
i just googled "bike crank length claculator"



if you have a better formula i'll gladly try it.

I am average height and by the listed .41 x tibia length I get 168mm.

I went down a rabit hole last year after picking up a used bike with 170mm cranks and was worried that they were shorter than I was used to running, (spoiler, didn't notice the difference). To be fair there are sources that are all over the place and most will agree it isn't a huge deal one way or the other.. So pick a crank that works for your bike and riding conditions and be a dick about it.

Longer cranks will give you more torque while standing on the pedals, will give you a lower COG for seated pedaling, reduced pedal clearance for a given BB height.

Shorter cranks will favor spinning, allow a lower BB for pedal clearance, can reduce knee pain if that is a problem but will reduce standing torque and raise your seated pedaling COG.
 

Cerberus75

Monkey
Feb 18, 2017
349
122
I've been riding 165mm cranks for years. I liked 160mm better but with my bike having a high BB my COG felt tippy seated. The new bike is lower so I might try 160mm again. I have short legs so Shor cranks work for me.
 

HardtailHack

used an iron once
Jan 20, 2009
3,068
802
have you heard about ergonomics?
Yup, I had my current frame made with a 142mm back end and had the stays kick out as far back as possible so I could run lower Q-factor cranks. I find modern MTB cranks to be pretty uncomfortable on longer rides, the diameter of the circle that my legs spin at doesn't seem to make a difference to me, didn't with 155mm either.
 

Andeh

Customer Title
Mar 3, 2020
268
313
A local guy got one cheap off Jenson a year or so ago. The seat tube design is awful, he can only run like a 125 on his size medium, and it's got to be externally routed.
 

slyfink

Turbo Monkey
Sep 16, 2008
7,290
2,971
Ottawa, Canada
1623173360173.png


Commençal Press Release said:
We are proud to present our new Commencal Supreme!

It's a prototype, a lab bike that means we can try many new concepts under the most testing and extreme conditions.

In order to work with a minimum of unknowns, we use a lot of tubes from our current bikes and this allows us to ensure perfect management of stiffness as well as limiting the risks in terms of resistance. This Supreme features a brand new kinematic with a Virtual High Pivot. Through this system, we're always looking for more performance and liveliness, without compromising the capacity of our now renowned High Pivot Point.

There is no commercialisation on the cards yet, however it’s sure that this is the dawn of a new era for the future of Commenca lDH.
But... Don't UCI rules stipulate that a bike has to go into production within a certain specific time frame in order to be raced at World Cups? In other words, no FRO bikes?
 

slimshady

¡Mira, una ardilla!
View attachment 161054

" Press Release: Commencal

We are proud to present our new Commencal Supreme!

It's a prototype, a lab bike that means we can try many new concepts under the most testing and extreme conditions.

In order to work with a minimum of unknowns, we use a lot of tubes from our current bikes and this allows us to ensure perfect management of stiffness as well as limiting the risks in terms of resistance. This Supreme features a brand new kinematic with a Virtual High Pivot. Through this system, we're always looking for more performance and liveliness, without compromising the capacity of our now renowned High Pivot Point.

There is no commercialisation on the cards yet, however it’s sure that this is the dawn of a new era for the future of Commenca lDH. "
But... Don't UCI rules stipulate that a bike has to go into production within a certain specific time frame in order to be raced at World Cups? In other words, no FRO bikes?
This looks prototype:



This screams production:

 

jonKranked

Press Button, Receive Stupid
Nov 10, 2005
69,634
12,566
media blackout
View attachment 161054


But... Don't UCI rules stipulate that a bike has to go into production within a certain specific time frame in order to be raced at World Cups? In other words, no FRO bikes?
came here to post that aspect. they have a 12 month window (i believe its 12 months) to race it before it goes into production. if it doesn't go into production or get substantially altered with extension approval from the UCI they must stop racing it.
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,216
585
SWE
What about Bruni's bike with custom geometry and custom linkage? It looks very close to the serial Demo but it is different...
I am curious about what the pros would ride if that rule didn't exist
 

slimshady

¡Mira, una ardilla!
there is also a pivot on the chainstay near the rear axle.

View attachment 161057
Yes, I instantly thought of the Equilink when I saw the pictures. However, there seems to be a tunnel above the BB, which would allow for the lower link to attach to the shock. The chainstays attach to the lower link below the main pivot point, as in the original Equilink.

EDIT: here is a better pic:



Also, the shock doesn't seem to be attached to the main triangle:

 
Last edited: