Crank size difference--will it really help?

I doubt that it would make much difference to you. I have three bikes
that I switch between regularly. The tandem has 165 mm cranks, the
folding travel bike has 170 mm, and my usual road bike has 175 mm. If
I pay attention it seems to me that I spin a bit faster with the 165s,
but the difference is minimal and I can't say I notice any clear
benefit of one length vs. the others.
If you had any specific knee problems with the longer cranks then I
could see the rationale for switching to shorter ones. But I wouldn't
bother if you don't have any particular issues that you can attribute
to the longer cranks.

caaron wrote:
I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I was
getting refitted to the bike to help with numbness in my hands and we ended
up moving the seat position and also raising the handlebars. After we did
that it was suggested that I should really be riding on 165mm cranks because
I have short legs. I'm seeking opinions

Will there be a noticeable difference in performance with shorter cranks?

Probably not.


How hard is it to change out Ultegra cranks

Not very.

--do I need special tools?

Yes


Do I change the cranks themselves or do I also have to change the gears (it
is a triple) with the cranks as a set?

Yes.

Well, my seat is higher than that--74cm above the bottom bracket to the top
of the seat and 23cm above the top tube. I had it lower but it felt
cramped and when I raised it to this height I got better spinning and more
power.

Chuck

"Mike Jacoubowsky" wrote in message
.. .
I ride a 2001 Trek 5200 that is 54cm. I'm 163# and just short of 5'9"
tall and have a long torso and short legs. My inseam is 30" and the
distance from the top of my femur to the floor is 89cm. Based on Peter
White's 18.5% calculation guideline, 165mm cranks would be just right.
Similar calculations from Ergobike (edward ZImmermann's bicycle sizing
site) also come out at 165mm.

Previously I had a 58cm Trek 5200, which I found too big to ride
comfortably, so I got the 54cm Trek a few years ago and it seems to be a
better fit. At age 60 I find I need the handlebars higher for comfort
and I'm a recreational rider, not a racer, so my rides average about
15mph. I've always had trouble spinning fast, and although I can get up
into the high 90's I find my average cadence is in the low to
mid-eighties on most of my road rides. So I was wondering if changing
over to the 165mm cranks would make enough of a difference in comfort and
cadence to make it worthwhile to do the change and what downside there
might be, if any...

Thanks for the replies

Chuck

What are you using for saddle height (measured from center of crank to top
of saddle)? Traditional wisdom would be around 66cm if I'm figuring
correctly, which, on a 54cm Trek, would place the top of the saddle
13-14cm above the top tube (or 12cm above the seat collar, which extends
above the top tube a bit and represents the measuring point for frame size
on a 5200).

Those all sound like pretty normal measurements (if they're reasonably
close to what's on your bike). If so, I find nothing there to indicate
that there's any "need", based on leg length, for a shorter crank. You
might wish to try one for the heck of it, but I'm not sure what symptoms
need to be addressed, particularly in light of your stated RPMs which are
*not* at the low end. Low-to-mid-80s are perfectly acceptable for most
people; not everyone does well spinning like Lance.

I'm also somewhat concerned by what sounds like a hit-and-miss approach to
fit. How did you end up initially with a 58cm frame? When I mock that one
up, it looks like the saddle would be almost sitting on top of the top
tube. You're potentially over-compensating and swinging from one extreme
to the other, when someplace in the middle might be just about right.

But getting down to the effects of shorter cranks- generally, you'll be
able to spin a bit more (because the crank is traveling through a smaller
circle, so your feet aren't actually moving as far/fast per revolution),
but you'll also be losing some leverage, which could be an issue climbing.
In general there's a trend toward longer cranks these days, seemingly with
little downside (we're not seeing more knee injuries today than
back-in-the-day, even though there are more people serious mile now than
back then).

Good luck, and let us know how the experiment turns out-

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

165 may be right for you if you have shorter than average legs. i ride
a 54" frame and 170 cranks. i can feel the difference between 175 and
170. i haven't tried any other size. and i definitely prefer the 170.

Well, my seat is higher than that--74cm above the bottom bracket to the
top of the seat and 23cm above the top tube. I had it lower but it felt
cramped and when I raised it to this height I got better spinning and more
power.

Chuck

Chuck: Have you had a fitting done by somebody who does more than have you
stand over the top tube? By that I mean measurements (arm, torso, inseam,
shoulders etc), turn that into a mock fit and then observe the results?
Self-fit doesn't always work too well; measurements can be off, and there's
nobody to observe the results and notice things like rocking hips, toes-down
pedaling, arched (curved) back etc.

A really good fitting person isn't useful just for high-speed
performance-oriented riding. Indeed, if you get someone who starts talking
about getting you into a lower position for "efficiency", you've got the
wrong person.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


"caaron" wrote in message
...
Well, my seat is higher than that--74cm above the bottom bracket to the
top of the seat and 23cm above the top tube. I had it lower but it felt
cramped and when I raised it to this height I got better spinning and more
power.

Chuck

"Mike Jacoubowsky" wrote in message
.. .
I ride a 2001 Trek 5200 that is 54cm. I'm 163# and just short of 5'9"
tall and have a long torso and short legs. My inseam is 30" and the
distance from the top of my femur to the floor is 89cm. Based on Peter
White's 18.5% calculation guideline, 165mm cranks would be just right.
Similar calculations from Ergobike (edward ZImmermann's bicycle sizing
site) also come out at 165mm.

Previously I had a 58cm Trek 5200, which I found too big to ride
comfortably, so I got the 54cm Trek a few years ago and it seems to be a
better fit. At age 60 I find I need the handlebars higher for comfort
and I'm a recreational rider, not a racer, so my rides average about
15mph. I've always had trouble spinning fast, and although I can get up
into the high 90's I find my average cadence is in the low to
mid-eighties on most of my road rides. So I was wondering if changing
over to the 165mm cranks would make enough of a difference in comfort
and cadence to make it worthwhile to do the change and what downside
there might be, if any...

Thanks for the replies

Chuck

What are you using for saddle height (measured from center of crank to
top of saddle)? Traditional wisdom would be around 66cm if I'm figuring
correctly, which, on a 54cm Trek, would place the top of the saddle
13-14cm above the top tube (or 12cm above the seat collar, which extends
above the top tube a bit and represents the measuring point for frame
size on a 5200).

Those all sound like pretty normal measurements (if they're reasonably
close to what's on your bike). If so, I find nothing there to indicate
that there's any "need", based on leg length, for a shorter crank. You
might wish to try one for the heck of it, but I'm not sure what symptoms
need to be addressed, particularly in light of your stated RPMs which are
*not* at the low end. Low-to-mid-80s are perfectly acceptable for most
people; not everyone does well spinning like Lance.

I'm also somewhat concerned by what sounds like a hit-and-miss approach
to fit. How did you end up initially with a 58cm frame? When I mock that
one up, it looks like the saddle would be almost sitting on top of the
top tube. You're potentially over-compensating and swinging from one
extreme to the other, when someplace in the middle might be just about
right.

But getting down to the effects of shorter cranks- generally, you'll be
able to spin a bit more (because the crank is traveling through a smaller
circle, so your feet aren't actually moving as far/fast per revolution),
but you'll also be losing some leverage, which could be an issue
climbing. In general there's a trend toward longer cranks these days,
seemingly with little downside (we're not seeing more knee injuries today
than back-in-the-day, even though there are more people serious mile now
than back then).

Good luck, and let us know how the experiment turns out-

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

Yes, I actually was fitted by a good, independent bike shop and it was there
that we moved the seat back and up, so that was definitely an improvement.
They asked me about my riding style and physical problems (back, neck &
shoulder pain) and made adjustments to the bike. Then I rode it on the bike
stand while they observed and they fine tuned from there. The conclusion
was that the adjustments to this bike were a good compromise but that I'd
never really find a bike that fit my body size ideally without having a
custom frame made. They did pick up my toes-down pedaling style but I think
that's improved since we moved the seat back. The problem I've had with fit
is that every shop where I've asked advice has a different idea as to what
proper fit really is. Some don't consider the comfort needs of the older
rider and others (many of whom seem like they really do understand fit) tend
to depend more on their visual evaluation of me on the bike than the "fit
kit" or other fitting aids. Afterwards I find myself taking their advice,
but still fine-tuning the fit based on my own comfort and ride experiences.
Prior to that I had my wife take accurate measurements and tried the formula
route with various on-line fitting guides. The problem there is that again,
many are designed for optimum racing fit for a 24 year old rider, which I'm
not. And there were also variations for frame types, seat back angles, etc.
Even then, the results came out anywhere between a 54 and 58cm bike, which
is a big difference. But when I looked back on my calculations last night,
most of them agreed that I should be using 165mm cranks...

My question about the crank lengths really came from a recent visit to my
Orthopedic doctor, who is a cycler himself. In fact, he shared with me that
about 20 some years ago he bought a frame from Eddie Merckx and welded it
himself and still has the bike he built from it today. Anyway I had been
reading Peter White's bike fitting article (which makes good sense) and
mentioned the 18.5% crank length formula to my Dr, and he was kind enough to
measure my leg length while I was there. So that is why I asked the
question about crank length, since the guidelines call for 165mm and I'm
riding on 172.5mm. I don't mind spending the money for a new crankset, but
was curious as to how much the 7.5mm difference might make and how difficult
it would be to make the change myself. Sounds like an easy mechanical
change and after reading many of the replies here, I'm inclined to spend the
money to buy a shorter crank set.

Chuck


"Mike Jacoubowsky" wrote in message
. ..
Well, my seat is higher than that--74cm above the bottom bracket to the
top of the seat and 23cm above the top tube. I had it lower but it felt
cramped and when I raised it to this height I got better spinning and
more power.

Chuck

Chuck: Have you had a fitting done by somebody who does more than have you
stand over the top tube? By that I mean measurements (arm, torso, inseam,
shoulders etc), turn that into a mock fit and then observe the results?
Self-fit doesn't always work too well; measurements can be off, and
there's nobody to observe the results and notice things like rocking hips,
toes-down pedaling, arched (curved) back etc.

A really good fitting person isn't useful just for high-speed
performance-oriented riding. Indeed, if you get someone who starts talking
about getting you into a lower position for "efficiency", you've got the
wrong person.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


"caaron" wrote in message
...
Well, my seat is higher than that--74cm above the bottom bracket to the
top of the seat and 23cm above the top tube. I had it lower but it felt
cramped and when I raised it to this height I got better spinning and
more power.

Chuck

"Mike Jacoubowsky" wrote in message
.. .
I ride a 2001 Trek 5200 that is 54cm. I'm 163# and just short of 5'9"
tall and have a long torso and short legs. My inseam is 30" and the
distance from the top of my femur to the floor is 89cm. Based on
Peter White's 18.5% calculation guideline, 165mm cranks would be just
right. Similar calculations from Ergobike (edward ZImmermann's bicycle
sizing site) also come out at 165mm.

Previously I had a 58cm Trek 5200, which I found too big to ride
comfortably, so I got the 54cm Trek a few years ago and it seems to be
a better fit. At age 60 I find I need the handlebars higher for
comfort and I'm a recreational rider, not a racer, so my rides average
about 15mph. I've always had trouble spinning fast, and although I can
get up into the high 90's I find my average cadence is in the low to
mid-eighties on most of my road rides. So I was wondering if changing
over to the 165mm cranks would make enough of a difference in comfort
and cadence to make it worthwhile to do the change and what downside
there might be, if any...

Thanks for the replies

Chuck

What are you using for saddle height (measured from center of crank to
top of saddle)? Traditional wisdom would be around 66cm if I'm figuring
correctly, which, on a 54cm Trek, would place the top of the saddle
13-14cm above the top tube (or 12cm above the seat collar, which extends
above the top tube a bit and represents the measuring point for frame
size on a 5200).

Those all sound like pretty normal measurements (if they're reasonably
close to what's on your bike). If so, I find nothing there to indicate
that there's any "need", based on leg length, for a shorter crank. You
might wish to try one for the heck of it, but I'm not sure what symptoms
need to be addressed, particularly in light of your stated RPMs which
are *not* at the low end. Low-to-mid-80s are perfectly acceptable for
most people; not everyone does well spinning like Lance.

I'm also somewhat concerned by what sounds like a hit-and-miss approach
to fit. How did you end up initially with a 58cm frame? When I mock that
one up, it looks like the saddle would be almost sitting on top of the
top tube. You're potentially over-compensating and swinging from one
extreme to the other, when someplace in the middle might be just about
right.

But getting down to the effects of shorter cranks- generally, you'll be
able to spin a bit more (because the crank is traveling through a
smaller circle, so your feet aren't actually moving as far/fast per
revolution), but you'll also be losing some leverage, which could be an
issue climbing. In general there's a trend toward longer cranks these
days, seemingly with little downside (we're not seeing more knee
injuries today than back-in-the-day, even though there are more people
serious mile now than back then).

Good luck, and let us know how the experiment turns out-

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

Hi... my advice?... get a set of 170 cranks... 165 are too short.... u'll
get more power and more consistency using 170. !72.5 is way too long for u
specially if u r kind'a short person u know... thats the reason because u
have pain on your knees (not new), ALthoug i can use 172.5 i might suffer
some pain in my knees because of that little difference.

Probably u'll feel some performance difference with 165, why? because the
torque is a lot less than with a 172.5 especially in higher gears (hope ur
not one of those riders). If i was u i would get a set of 170 set of
cranks... 165 are too short even for u.(if u are using the same bike ull
feel the difference, maybe with another frame u wont, it depends not all
the bikes are the same set ups)

As experience, books always say something. formulas for this and this and
people from the LBS giving u advice about what is ok and what is not ok.
(some LBS people havent riden even in a tricycle but they had read a lot).
The problem is that rules arent always the same, rules and formulas depends
of many factor and usually they take only an average person.

Fausto coppy style was awefull but the guy was god damm fast... good
example right?

AN extreme case i remember, over here in xxxx a triatlhete woman. She had
the best bike in the market, the guys from the store were trying t get the
best position for her (she wanted the same) blah blah... I saw her last
custom made bicycle... was something hmmm... weird... she was pettite too..
well that day this woman went there to try that new frame (the 4th one), I
saw her on hte parking lot riding and I notice that no matter what frame
they built for her, her style will continue being crappy. I have no idea if
she is still trying to get a position as Greg Lemond but I bet that the
store people didnt say that the problem was her and her shortness to this
poor woman, there was nothing else to do. besides taking her money... or
maybe teach her how to really ride a bike and improve her style (no store
will teach u that)

As a general rule, usually short people have problems with their position
over the bike specially if the style and tecnnique is bad. Dunno if this is
your case... but usually thats what happens.


I saw in nashbar i think a set of cranks quite cheap and they look cool
too...

Cya...



PS: numbness in my hands --- the seat is pointing to the ground, set the
seat level with the ground thats all u have to do, btw maybe you ride
putting all your weight over the front of the bike, and if thats the
case... i thnk we found the source of all your problems.






Peter Cole wrote in
:

caaron wrote:
I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I
was getting refitted to the bike to help with numbness in my hands
and we ended up moving the seat position and also raising the
handlebars. After we did that it was suggested that I should really
be riding on 165mm cranks because I have short legs. I'm seeking
opinions

Will there be a noticeable difference in performance with shorter
cranks?

Probably not.


How hard is it to change out Ultegra cranks

Not very.

--do I need special tools?

Yes


Do I change the cranks themselves or do I also have to change the
gears (it is a triple) with the cranks as a set?

Yes.

On Tue, 27 Sep 2005 07:06:34 -0500, noname wrote:

Hi... my advice?... get a set of 170 cranks... 165 are too short.... u'll
get more power and more consistency using 170. !72.5 is way too long for u
specially if u r kind'a short person u know... thats the reason because u
have pain on your knees (not new), ALthoug i can use 172.5 i might suffer
some pain in my knees because of that little difference.
"172.5 is way too long for u", so, " get a set of 170 cranks". Do
you really think that 2.5mm is "way too long"? If the OP is having
knee pain, it is more likely due to the cleat alignment, and/or saddle
position[height, kops]. Here see what Sheldon has to say:
http://www.sheldonbrown.com/pain.html#knees

Pain and cycling, in general: http://www.sheldonbrown.com/pain.html

I have to believe that for all but a true professional bike racer,
changing out cranks for 2.5mm is a waste of time and money. Sure, if
you are replacing your wornout crankset, or building a new bike, then
go to the 170, but don't do it just to change size.


Probably u'll feel some performance difference with 165, why? because the
torque is a lot less than with a 172.5 especially in higher gears (hope ur
not one of those riders). If i was u i would get a set of 170 set of
cranks... 165 are too short even for u.(if u are using the same bike ull
feel the difference, maybe with another frame u wont, it depends not all
the bikes are the same set ups)

As experience, books always say something. formulas for this and this and
people from the LBS giving u advice about what is ok and what is not ok.
(some LBS people havent riden even in a tricycle but they had read a lot).
The problem is that rules arent always the same, rules and formulas depends
of many factor and usually they take only an average person.

Fausto coppy style was awefull but the guy was god damm fast... good
example right?

AN extreme case i remember, over here in xxxx a triatlhete woman. She had
the best bike in the market, the guys from the store were trying t get the
best position for her (she wanted the same) blah blah... I saw her last
custom made bicycle... was something hmmm... weird... she was pettite too..
well that day this woman went there to try that new frame (the 4th one), I
saw her on hte parking lot riding and I notice that no matter what frame
they built for her, her style will continue being crappy. I have no idea if
she is still trying to get a position as Greg Lemond but I bet that the
store people didnt say that the problem was her and her shortness to this
poor woman, there was nothing else to do. besides taking her money... or
maybe teach her how to really ride a bike and improve her style (no store
will teach u that)

So, you are saying, because she is short, they can't build a bike to
fit her? That is the whole idea of going custom, to be able to cut the
tubes to nonstandard sizes. If they can't size the bike properly, it
is either their incompetence or her requesting/demanding incorrect
lengths.

As a general rule, usually short people have problems with their position
over the bike specially if the style and tecnnique is bad. Dunno if this is
your case... but usually thats what happens.
As a general rule, really tall people have problems with their
position over the bike especially if the style and technique is bad.
This statement is as absurd as yours. If your style and technique is
bad, your height isn't the issue.


I saw in nashbar i think a set of cranks quite cheap and they look cool
too...

Cya...



PS: numbness in my hands --- the seat is pointing to the ground, set the
seat level with the ground thats all u have to do, btw maybe you ride
putting all your weight over the front of the bike, and if thats the
case... i thnk we found the source of all your problems.

There are way too many people giving advice, as absolutes. If I have
learned nothing else on these newsgroups, it is that when it comes to
bicyle fit and sizing, there are few absolutes.


Life is Good!
Jeff

Thanks for all of the responses to my question. I actually did buy and
install the Ultegra 165's and the results were dramatic--much easier riding
with less effort, and an increase in cadence by close to 10rpm along with an
average speed increase of about .7mph (seven tenths).

My bike finally feels comfortable to ride--hard to believe that such a
seemingly minor change of 7.5mm could make such a dramatic difference in
performance. And the cranks were ridiculously easy to install, so it is a
trivial mechanical procedure.

Thanks again.

Chuck


"caaron" wrote in message
...
I've been riding my Trek 5200 with 172.5 Ultegra cranks. Recently I was
getting refitted to the bike to help with numbness in my hands and we
ended up moving the seat position and also raising the handlebars. After
we did that it was suggested that I should really be riding on 165mm
cranks because I have short legs. I'm seeking opinions

Will there be a noticeable difference in performance with shorter cranks?

How hard is it to change out Ultegra cranks--do I need special tools?

Do I change the cranks themselves or do I also have to change the gears
(it is a triple) with the cranks as a set?

Thanks in advance...

Chuck

"caaron" wrote:

Thanks for all of the responses to my question. I actually did buy and
install the Ultegra 165's and the results were dramatic--much easier riding
with less effort, and an increase in cadence by close to 10rpm along with an
average speed increase of about .7mph (seven tenths).

My bike finally feels comfortable to ride--hard to believe that such a
seemingly minor change of 7.5mm could make such a dramatic difference in
performance. And the cranks were ridiculously easy to install, so it is a
trivial mechanical procedure.

Did you use a torque wrench?

--
Ted Bennett