170 vs 175 cranks

my trusty tourer/commuter has 170 stronglights, my new race bike has 17
plastics. Only done the one short ride so I haven't noticed.
Hows it going to work, riding 170s regularly & 175s hard?

Must finish big bowl of leggoed pasta before I can take new bike fo
2nd ride, ETD 11pm; 1 hour so the food won't hit or a trainin
handicap

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aeek

"aeek" wrote in message

my trusty tourer/commuter has 170 stronglights, my new race bike has
175 plastics. Only done the one short ride so I haven't noticed.
Hows it going to work, riding 170s regularly & 175s hard?

The longer the crank arms the more you grind rather than spin. Unless
you're quite tall you're better off with 170s.

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A: Top-posters.
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"fred_nieman" wrote in message


The date on your computer is still wrong.

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A: Top-posters.
Q: What is the most annoying thing on Usenet?

"aeek"

my trusty tourer/commuter has 170 stronglights, my new race bike has 175
plastics. Only done the one short ride so I haven't noticed.
Hows it going to work, riding 170s regularly & 175s hard?

I thought the most common road crank was 172.5
and 175 for mtb's?

It's not optimal to be switching but I'm assuming you
aren't about to beat Lance up a big hill?

I swap between 165 track, 172.5 road and 175 mtb
and there is a slight difference but nothing really bad.

hippy

"hippy" wrote in message ...
"aeek"

my trusty tourer/commuter has 170 stronglights, my new race bike has 175
plastics. Only done the one short ride so I haven't noticed.
Hows it going to work, riding 170s regularly & 175s hard?

I thought the most common road crank was 172.5
and 175 for mtb's?

It's not optimal to be switching but I'm assuming you
aren't about to beat Lance up a big hill?

I swap between 165 track, 172.5 road and 175 mtb
and there is a slight difference but nothing really bad.

hippy

I've got 165 on the r!*d bike, 175 on the FS & HT and 180 on the SS. Going from 180 to 165 feels very strange but any other change
I don't seem to notice.

Parbs

hippy Wrote:
"
I swap between 165 track, 172.5 road and 175 mtb
and there is a slight difference but nothing really bad.


I've recently gone the other way, consolidating all my bikes to 175 s
they all feel the same to ride. 165's is standard issue for trac
bikes, but I'm much happy with a single crank length (and yes, I ca
spin 175's to a maximal cadence of 180 before anyone pipes up)

--
Shabby

DRS Wrote:
The longer the crank arms the more you grind rather than spin. Unles
you're quite tall you're better off with 170s.

But it balances out as you are likely to be producing (around) the sam
force - you 'grind' to compensate for the larger distance your foot ha
to travel on a 175. So, at a given power your force production and foo
speed is basically the same, but your cadence is lower. This isn't muc
of an issue.

What is an issue is that cycling has a large neuromuscular component
this component is easily trainable, but trained at specific join
angles. When crank length changes, so do joint angles. Consequently i
you change from a crank length you are used to, you are very likely t
find you have a lower peak power (over 1-60 seconds) and also that a
constant power your central motor units (nervous system control) fail
quicker. That is, you can't sprint as fast and your legs will di
quicker.

Within reason (provided there are not specific biomechanical issues)
most crank lengths can be adapted to, and the scientific literatur
demonstrates that where time is given for that adaption to occur, ther
is no difference in peak powers or time to fatigue between cran
lengths. I'm not saying you should run 165's on your roadie if you ar
6'6", just that within reason you don't need to stress much about cran
length (also that much of what people say about crank length is founde
in myth).

So: the take home lesson is it is better to ride the same crank lengt
on all your different bikes if you can. This means you will always b
training the same neuromuscular patterns at the same joint angles (i
your saddle and BB positions are also right) - thus you will be mor
comfortable and better trained on both bikes. If you have to rid
different length cranks (or can't be bothered changing or think I'
full of it) try to emulate the hip and knee angles you want to ride o
your race bike when you set up your training bike.

Cool - hope this helps. Fire away with some q's if you wan
clarification

--
Roadie_scum

Roadie_scum Wrote:

snip (lots of good stuff)

(also that much of what people say about crank length is founded in
myth)

So: the take home lesson is it is better to ride the same crank length
on all your different bikes if you can. This means you will always be
training the same neuromuscular patterns at the same joint angles (if
your saddle and BB positions are also right) - thus you will be more
comfortable and better trained on both bikes. If you have to ride
different length cranks (or can't be bothered changing or think I'm
full of it) try to emulate the hip and knee angles you want to ride on
your race bike when you set up your training bike.


It makes more sense to me that crank length be based on rider anatomy
than "everyone only needs XYZ mm".

I found it's really hard to have the same joint angles on different
types on bike, regardless of crank length.

The angles & riding position on my bikes vary so much that I couldn't
get them close. I've got 175, 180 & 183 (7.25") length cranks over 4
bikes. Changing the road bike from 170 to 180 was a noticable change
though.


--
Bikesoiler

aeek wrote:
my trusty tourer/commuter has 170 stronglights, my new race bike has 175
plastics. Only done the one short ride so I haven't noticed.
Hows it going to work, riding 170s regularly & 175s hard?

Must finish big bowl of leggoed pasta before I can take new bike for
2nd ride, ETD 11pm; 1 hour so the food won't hit or a training
handicap?


From my humble experience and many years of LBS advice:

Generally:
If you are petite-but-perfectly-formed (like your humble narrator, oh my
droogies) then 165 or 170 mm cranks are for you, but if you are a
long-legged type, 170s or 175s are the go.

It gets a little complicated, tho:
- If you are a (despite your size, tho they're generally thin and tall)
hill-climbing ("long twitch muscles" = good at aerobic endurance) type,
170 to 175 cranks, and 80-90 "cadence" rpm "tall gears" are the go;
- If you are a (despite your size, tho they're (ie: me) generally little
and stubby) sprinting ("short twitch muscles" = good at anaerobic
sprinting, but crap at anything but slow, slow endurance) type, 165 to
170 cranks, and and 90-105 "cadence" rpm "short gears" are the go.

It gets more complicated... despite your muscle type/body length:
- if you generally travel at low (10 - 25 km/h) speeds (touring or
commuting, for example), it's more efficient to have a high "cadence"
(which means shorter cranks and "short" gears)
- - if you generally travel at higher (25 km/h+ ) speeds (road racing or
easy x-country MTB, for example), it's more efficient to have a less
high "cadence" (80-90 rpm, which means longer cranks and "tall " gears)

It gets even even more more complicated when you talk about MTB racing.
I'm just not going to say anything about cyclo-X, technical X-C,
down-hill and so on, because I've said enough stoopid stuff already.

xxx

p

fred_nieman wrote:

In short:
Q: 170 vs 175 cranks?
A: what DRS said.

ps: am no longer on Tijuana time... %-P