splined crank arms [was RE: crank arms]

BTW, speaking of expensive cranks :

With splined crank arms, from what I understood, the attachment to the
axle is much stronger because of the splined grooves. OK, now is the
crank body itself much stronger also - I mean is the splined attachment
impacting on the stress limit of the crank before it snaps or bends ?

Oli-

-----Original Message----- From: Jeff Lutkus
[mailto:lutkus@unicyclist.com] Sent: Thursday, July 05, 2001 10:12 AM To:
Olivier Paugam; Jeff Lutkus
Cc: unicycling@winternet.com Subject: RE: crank arms

My limited knowledge physics tells me that yes, the crank arms will be
deformed to a certain degree, before returning back to their original
shape. If, however, the force you land with excedes the elastic limit of
the crank arms, they will not spring back.

My impression is that as you get into the "better" materials, the elastic
limit is not increased, but the amount that the pedals tend to flex with
the same force is decreased. By this logic, cheaper cranks would tend to
bend out of shape, whereas the more expensive ones would more likley snap
(though a lot more force would be required).

My uneducated guess would be that that this bending feeling is more due to
a flex in the spokes then anything with the cranks. It makes me wonder,
though, just how much flex the average set of crank arms have before they
break or become permanently misshapen. I would suspect if the cranks are
long enough, and have a good amount of flex, you very well could feel it.

Jeff Lutkus

--- "Olivier Paugam" <opaugam@aptilon.com>

[color=blue]> wrote:[/color]

[color=blue]>That's funny, this strange feeling happened to me yesterday actually[/color]

[color=blue]>with[/color]

[color=blue]>my monty uni.[/color]

[color=blue]>I was doing a 2' drop on a steep slope, landed quite brutally and[/color]
really

[color=blue]>felt the right crank bending. When I reached flat ground I checked the[/color]

[color=blue]>crank[/color]

[color=blue]>and mysteriously it was intact.[/color]

[color=blue]>[/color]

[color=blue]>I'm wondering if a crank can really deform slightly and get back to its[/color]

[color=blue]>primary shape or it's just an illusion maybe due to the shock on the[/color]

[color=blue]>lower[/color]

[color=blue]>leg / unprepared / over-contracted muscles ?[/color]

[color=blue]>[/color]

[color=blue]>As a matter of fact I never bent my bicycle euro 140mm on trials.[/color]

[color=blue]>[/color]

[color=blue]>Oli-[/color]

[color=blue]>[/color]

[color=blue]>-----Original Message-----[/color]

[color=blue]>From: Jeff Lutkus [mailto:lutkus@unicyclist.com][/color]

[color=blue]>Sent: Thursday, July 05, 2001 8:42 AM[/color]

[color=blue]>To: unicycling@winternet.com[/color]

[color=blue]>Subject: crank arms[/color]

[color=blue]>[/color]

[color=blue]>[/color]

[color=blue]>I discovered today that inexpensive crank arms may be fine for street[/color]

[color=blue]>riding, but not for muni. So, does anyone have any recommendations on[/color]

[color=blue]>who makes a good (yet still, hopefully, inexpensive) crank arm? As the[/color]

[color=blue]>terrain is quite flat around here, I'm probably looking at a 6" size.[/color]

[color=blue]>[/color]

[color=blue]>I borrowed the crank arms from my Coker because they were the right[/color]

[color=blue]>length. I really should have thought that through before I took them[/color]

[color=blue]>into the woods. I had to make a 6" jump up to a bridge, and I landed[/color]

[color=blue]>just hard enough to bend one crank to the point where I could feel, but[/color]

[color=blue]>not see the bend. Well, after that, I figured it wouldn't make much[/color]

[color=blue]>difference if I went for a 3' drop.=20[/color]

[color=blue]>[/color]

[color=blue]>http://www.rit.edu/~jvl2957/bent_crank.jpg[/color]

[color=blue]>[/color]

[color=blue]>That drop had the oddest feel -- I felt the shock of the landing as it[/color]

[color=blue]>was absorbed by the pedal... which, unlike other drops I've made on my[/color]

[color=blue]>20" uni, did not apply any of that force back to my foot.[/color]

[color=blue]>[/color]

[color=blue]>Also learned that day, riding a mile on a dirt trail with two bent[/color]

[color=blue]>cranks can be interesting.[/color]

[color=blue]>[/color]

[color=blue]>Jeff Lutkus[/color]

[color=blue]>[/color]

[color=blue]>[/color]

[color=blue]>_____________________________________________________________[/color]

[color=blue]>Free e-Mail and Webspace - http://Unicyclist.com[/color]

_____________________________________________________________
Free e-Mail and Webspace - http://Unicyclist.com

--- Olivier Paugam <opaugam@aptilon.com> wrote:
[color=blue]> BTW, speaking of expensive cranks :[/color]
[color=blue]>[/color]
[color=blue]> With splined crank arms, from what I understood, the attachment to the[/color]
[color=blue]> axle is much stronger because of the splined grooves. OK, now is the[/color]
[color=blue]> crank body itself much stronger also...[/color]

The crank body is definately stronger. They feel quite different than
cheap cranks, because they are totally stiff- no flex at all when landing
off any drop.

I've never bent the regular Profile cranks although some people certainly
have; Profile also makes dirt jumping cranks that are even stronger.

-Kris.

[color=blue]> impacting on the stress limit of the crank before it snaps or bends ?[/color]
[color=blue]>[/color]
[color=blue]> Oli-[/color]
[color=blue]>[/color]
[color=blue]> -----Original Message----- From: Jeff Lutkus[/color]
[color=blue]> [mailto:lutkus@unicyclist.com] Sent: Thursday, July 05, 2001 10:12 AM[/color]
[color=blue]> To: Olivier Paugam; Jeff Lutkus[/color]
[color=blue]> Cc: unicycling@winternet.com Subject: RE: crank arms[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]> My limited knowledge physics tells me that yes, the crank arms will be[/color]
[color=blue]> deformed to a certain degree, before returning back to their original[/color]
[color=blue]> shape. If, however, the force you land with excedes the elastic limit of[/color]
[color=blue]> the crank arms, they will not spring back.[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]> My impression is that as you get into the "better" materials, the[/color]
[color=blue]> elastic limit is not increased, but the amount that the pedals tend to[/color]
[color=blue]> flex with the same force is decreased. By this logic, cheaper cranks[/color]
[color=blue]> would tend to bend out of shape, whereas the more expensive ones would[/color]
[color=blue]> more likley snap (though a lot more force would be required).[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]> My uneducated guess would be that that this bending feeling is more due[/color]
[color=blue]> to a flex in the spokes then anything with the cranks. It makes me[/color]
[color=blue]> wonder, though, just how much flex the average set of crank arms have[/color]
[color=blue]> before they break or become permanently misshapen. I would suspect if[/color]
[color=blue]> the cranks are long enough, and have a good amount of flex, you very[/color]
[color=blue]> well could feel it.[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]> Jeff Lutkus[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]> --- "Olivier Paugam" <opaugam@aptilon.com>[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> > wrote:[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >That's funny, this strange feeling happened to me yesterday actually[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >with[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >my monty uni.[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >I was doing a 2' drop on a steep slope, landed quite brutally and[/color]
[color=blue]> really[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >felt the right crank bending. When I reached flat ground I checked the[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >crank[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >and mysteriously it was intact.[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >I'm wondering if a crank can really deform slightly and get back to its[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >primary shape or it's just an illusion maybe due to the shock on the[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >lower[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >leg / unprepared / over-contracted muscles ?[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >As a matter of fact I never bent my bicycle euro 140mm on trials.[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >Oli-[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >-----Original Message-----[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >From: Jeff Lutkus [mailto:lutkus@unicyclist.com][/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >Sent: Thursday, July 05, 2001 8:42 AM[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >To: unicycling@winternet.com[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >Subject: crank arms[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >I discovered today that inexpensive crank arms may be fine for street[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >riding, but not for muni. So, does anyone have any recommendations on[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >who makes a good (yet still, hopefully, inexpensive) crank arm? As the[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >terrain is quite flat around here, I'm probably looking at a 6" size.[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >I borrowed the crank arms from my Coker because they were the right[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >length. I really should have thought that through before I took them[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >into the woods. I had to make a 6" jump up to a bridge, and I landed[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >just hard enough to bend one crank to the point where I could feel, but[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >not see the bend. Well, after that, I figured it wouldn't make much[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >difference if I went for a 3' drop.=20[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >http://www.rit.edu/~jvl2957/bent_crank.jpg[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >That drop had the oddest feel -- I felt the shock of the landing as it[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >was absorbed by the pedal... which, unlike other drops I've made on my[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >20" uni, did not apply any of that force back to my foot.[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >Also learned that day, riding a mile on a dirt trail with two bent[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >cranks can be interesting.[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >Jeff Lutkus[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >_____________________________________________________________[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> >Free e-Mail and Webspace - http://Unicyclist.com[/color]
[color=blue]>[/color]
[color=blue]> _____________________________________________________________[/color]
[color=blue]> Free e-Mail and Webspace - http://Unicyclist.com[/color]

__________________________________________________
Do You Yahoo!? Get personalized email addresses from Yahoo! Mail
http://personal.mail.yahoo.com/

This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.

------_=_NextPart_000_01C10570.32CCC080

charset="iso-8859-1"

[color=blue]> OK, now is the crank body itself much stronger also - I mean is the[/color]
[color=blue]> splined attachment impacting on the stress limit of the crank before it[/color]
[color=blue]> snaps or bends ?[/color]

I think all the splined crank arms I've seen have been of hollow tubular
construction. This means they're a lot stronger than a cast or forged
piece of solid metal. But they can still break at the welds, as Chris
Reeder and others have demonstrated.

JF

------_=_NextPart_000_01C10570.32CCC080 Content-Type: application/ms-tnef

eJ8+IhcQAQaQCAAEAAAAAAABAAEAAQeQBgAIAAAA5AQAAAAAAADoAAEIgAcAGAAAAElQTS5N-
aWNy b3NvZnQgTWFpbC5Ob3RlADEIAQWAAwAOAAAA0QcHAAUACQAhABIABAAkAQEggAMADgA-
AANEHBwAF AAkAIQAWAAQAKAEBCYABACEAAABEMTY5QUQ1NjdDNkZENTExQTMzODAwMDJBNT-
I4NTE0MgDyBgEE gAEALAAAAFJFOiBzcGxpbmVkIGNyYW5rIGFybXMgW3dhcyBSRTogY3Jhb-
msgYXJtc10A+A4BDYAE AAIAAAACAAIAAQOQBgCgBwAAMgAAAAMANgAAAAAAAwAZgAggBgAA-
AAAAwAAAAAAAAEYAAAAAUoUA ACdqAQAeAB2ACCAGAAAAAADAAAAAAAAARgAAAABUhQAAAQA-
AAAQAAAA5LjAACwCEgAggBgAAAAAA wAAAAAAAAEYAAAAABoUAAAAAAAADAB6ACCAGAAAAAA-
DAAAAAAAAARgAAAAABhQAAAAAAAAsACoAI IAYAAAAAAMAAAAAAAABGAAAAAAOFAAAAAAAAC-
wAngAggBgAAAAAAwAAAAAAAAEYAAAAADoUAAAAA AAADAACACCAGAAAAAADAAAAAAAAARgAA-
AAAQhQAAAAAAAAMAKIAIIAYAAAAAAMAAAAAAAABGAAAA ABGFAAAAAAAAAwAqgAggBgAAAAA-
AwAAAAAAAAEYAAAAAGIUAAAAAAAAeADmACCAGAAAAAADAAAAA AAAARgAAAAA2hQAAAQAAAA-
EAAAAAAAAAHgA6gAggBgAAAAAAwAAAAAAAAEYAAAAAN4UAAAEAAAAB AAAAAAAAAB4AO4AII-
AYAAAAAAMAAAAAAAABGAAAAADiFAAABAAAAAQAAAAAAAAACAQkQAQAAAP0B AAD5AQAAxgIA-
AExaRnXMAVgOAwAKAHJjcGcxMjXiMgNDdGV4BUEBAwH3/wqAAqQD5AcTAoAP8wBQ BFY/CFU-
HshElDlEDAQIAY2jhCsBzZXQyBgAGwxEl9jMERhO3MBIsETMI7wn3tjsYHw4wNREiDGBj AF-
AzCwkBZDM2FlALpiA+gCBPSywgbm8H4MEEACB0aGUgBQAAcKRrIAbgZHkdgHQUEBBsZiBtGt-
Bo IHMydANgbmcSgQdAc2/QIC0gSR8QZQORHZT3CqIKgBzwcwtQC4AJgB/w+wJAANBoB4ACM-
CFGB3AK sORjdAuAZyACIB2zH3H3B5AEICHgbR6wI/AfAB3JDwEQBbAd4CURc25hcKcEIAWx-
JhBuZAQgPyFE /yFEIHAdwAuAHkAHQAMgJDMXIdUeBArAbQQgSSd2+yRRCeEgE+AqwSYQKxE-
lQQ5oBvAXsAfgdHVi df8LYAXABaAAgB+AGtAjsAIgeC4gVCigBCAgkh2jeeonJlFhJNBvJp-
Efhh3A8wORLxBjYR9wJwIm
MR/A9SIgcAiQYx3gJUEgICHglyIgB4ABkGwtwEJ1BUC/LpIwYQOgH3ADEAMgYhgg5mEo0TLjI-
Hce 4CdwHTDbMIASIGgFEAQgUgngBIH/H/AnYCPwHcEUACs0AQAEYJctIiJACYAuJ7pKRi-
FEAn05UAAA AB4AcAABAAAAKAAAAHNwbGluZWQgY3JhbmsgYXJtcyBbd2FzIFJFOiBjcmF-
uayBhcm1zXQACAXEA AQAAABYAAAABwQVwOB/JLUbTeIZHvaqwg4q3OY+JAAADACYAAAAA-
AAMALgAAAAAACwACAAEAAAAD AAlZAQAAAB4AQhABAAAAMAAAADw1MkNEMDJDM0RBRDJEN-
DExQTMxNzAwMDJBNTI4NTE0MjM0MzZC NkBTRVJWRVI+AAMA3j+vbwAAQAA5AIDAzDJwBc-
EBAwDxPwkEAAAeADFAAQAAAAUAAABKT0hOAAAA AAMAGkAAAAAAHgAwQAEAAAAFAAAASk9-
ITgAAAAADABlAAAAAAAMA/T/kBAAAAwCAEP////8CAUcA AQAAADcAAABjPVVTO2E9IDtw-
PUFuZGVyc29uU29sb25lSW47bD1TRVJWRVItMDEwNzA1MTYzMzE4 Wi03ODEAAAIB+T8BA-
AAATwAAAAAAAADcp0DIwEIQGrS5CAArL+GCAQAAAAAAAAAvTz1BTkRFUlNP TlNPTE9ORU-
lOQy9PVT1TQUMwL0NOPVJFQ0lQSUVOVFMvQ049Sk9ITgAAHgD4PwEAAAAKAAAASm9o biB-
Gb3NzAAAAHgA4QAEAAAAFAAAASk9ITgAAAAACAfs/AQAAAE8AAAAAAAAA3KdAyMBCEBq0u-
QgA Ky/hggEAAAAAAAAAL089QU5ERVJTT05TT0xPTkVJTkMvT1U9U0FDMC9DTj1SRUNJUE-
lFTlRTL0NO PUpPSE4AAB4A+j8BAAAACgAAAEpvaG4gRm9zcwAAAB4AOUABAAAABQAAAEp-
PSE4AAAAAQAAHMBio xTJwBcEBQAAIMLS5nTRwBcEBHgA9AAEAAAAFAAAAUkU6IAAAAAAe-
AB0OAQAAACgAAABzcGxpbmVk IGNyYW5rIGFybXMgW3dhcyBSRTogY3JhbmsgYXJtc10AH-
gA1EAEAAAAwAAAAPDUyQ0QwMkMzREFE MkQ0MTFBMzE3MDAwMkE1Mjg1MTQyMDZCNzJDQF-
NFUlZFUj4ACwApAAAAAAALACMAAAAAAAMABhDa faMlAwAHEEgBAAADABAQAQAAAAMAERA-
AAAAAHgAIEAEAAABlAAAAT0ssTk9XSVNUSEVDUkFOS0JP RFlJVFNFTEZNVUNIU1RST05H-
RVJBTFNPLUlNRUFOSVNUSEVTUExJTkVEQVRUQUNITUVOVElNUEFD VElOR09OVEhFU1RSR-
VNTTElNSVRPRlRIRQAAAAACAX8AAQAAADAAAAA8NTJDRDAyQzNEQUQyRDQx
MUEzMTcwMDAyQTUyODUxNDIwNkI3MkNAU0VSVkVSPgCYjA==

------_=_NextPart_000_01C10570.32CCC080--

I've broken 2 pairs this way- one pair of Bulletproof cranks (fit on the
DM ATU axle), and one pair of Fishbone cranks (fit on my old custom uni).
Both these cranks have a weld right where I broke them, and it looked like
there had been some fracturing and rusting from the inside-out, where I
broke them.

The Profile cranks are one-piece through this area (no welds). I think
this makes them stronger although they still seem to brake occasionally in
this high stress area. I've never had a problem though, and in any case
this would be a warranty issue.

-Kris --- Olivier Paugam <opaugam@aptilon.com> wrote:
[color=blue]> Kris, on Universe one of your crank (I assume it's splined since[/color]
[color=blue]> your uni seems to be a DM-ATU), just snaps on a landing. Did that[/color]
[color=blue]> happen often ?[/color]
[color=blue]>[/color]
[color=blue]> Oli-[/color]
[color=blue]>[/color]
[color=blue]> -----Original Message----- From: Kris Holm [mailto:danger_uni@yahoo.com][/color]
[color=blue]> Sent: Thursday, July 05, 2001 12:24 PM To: unicycling@winternet.com[/color]
[color=blue]> Subject: Re: splined crank arms [was RE: crank arms][/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]> --- Olivier Paugam <opaugam@aptilon.com> wrote:[/color]
[color={usenetquotecolor2}]> > BTW, speaking of expensive cranks :[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> > With splined crank arms, from what I understood, the attachment to[/color]
[color=blue]> the[/color]
[color={usenetquotecolor2}]> > axle is much stronger because of the splined grooves. OK, now is the[/color]
[color={usenetquotecolor2}]> > crank body itself much stronger also...[/color]
[color=blue]>[/color]
[color=blue]> The crank body is definately stronger. They feel quite different than[/color]
[color=blue]> cheap cranks, because they are totally stiff- no flex at all when[/color]
[color=blue]> landing off any drop.[/color]
[color=blue]>[/color]
[color=blue]> I've never bent the regular Profile cranks although some people[/color]
[color=blue]> certainly have; Profile also makes dirt jumping cranks that are even[/color]
[color=blue]> stronger.[/color]
[color=blue]>[/color]
[color=blue]> -Kris.[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color={usenetquotecolor2}]> > impacting on the stress limit of the crank before it snaps or bends ?[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> > Oli-[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> > -----Original Message----- From: Jeff Lutkus[/color]
[color={usenetquotecolor2}]> > [mailto:lutkus@unicyclist.com] Sent: Thursday, July 05, 2001 10:12 AM[/color]
[color={usenetquotecolor2}]> > To: Olivier Paugam; Jeff Lutkus[/color]
[color={usenetquotecolor2}]> > Cc: unicycling@winternet.com Subject: RE: crank arms[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> > My limited knowledge physics tells me that yes, the crank arms will be[/color]
[color={usenetquotecolor2}]> > deformed to a certain degree, before returning back to their original[/color]
[color={usenetquotecolor2}]> > shape. If, however, the force you land with excedes the elastic limit[/color]
[color={usenetquotecolor2}]> > of the crank arms, they will not spring back.[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> > My impression is that as you get into the "better" materials, the[/color]
[color={usenetquotecolor2}]> > elastic limit is not increased, but the amount that the pedals tend to[/color]
[color={usenetquotecolor2}]> > flex with the same force is decreased. By this logic, cheaper cranks[/color]
[color={usenetquotecolor2}]> > would tend to bend out of shape, whereas the more expensive ones would[/color]
[color={usenetquotecolor2}]> > more likley snap (though a lot more force would be required).[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> > My uneducated guess would be that that this bending feeling is more[/color]
[color=blue]> due[/color]
[color={usenetquotecolor2}]> > to a flex in the spokes then anything with the cranks. It makes me[/color]
[color={usenetquotecolor2}]> > wonder, though, just how much flex the average set of crank arms have[/color]
[color={usenetquotecolor2}]> > before they break or become permanently misshapen. I would suspect if[/color]
[color={usenetquotecolor2}]> > the cranks are long enough, and have a good amount of flex, you very[/color]
[color={usenetquotecolor2}]> > well could feel it.[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> > Jeff Lutkus[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> > --- "Olivier Paugam" <opaugam@aptilon.com>[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > > wrote:[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >That's funny, this strange feeling happened to me yesterday actually[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >with[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >my monty uni.[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >I was doing a 2' drop on a steep slope, landed quite brutally and[/color]
[color={usenetquotecolor2}]> > really[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >felt the right crank bending. When I reached flat ground I checked[/color]
[color=blue]> the[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >crank[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >and mysteriously it was intact.[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >I'm wondering if a crank can really deform slightly and get back to[/color]
[color=blue]> its[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >primary shape or it's just an illusion maybe due to the shock on the[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >lower[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >leg / unprepared / over-contracted muscles ?[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >As a matter of fact I never bent my bicycle euro 140mm on trials.[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >Oli-[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >-----Original Message-----[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >From: Jeff Lutkus [mailto:lutkus@unicyclist.com][/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >Sent: Thursday, July 05, 2001 8:42 AM[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >To: unicycling@winternet.com[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >Subject: crank arms[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >I discovered today that inexpensive crank arms may be fine for street[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >riding, but not for muni. So, does anyone have any recommendations[/color]
[color=blue]> on[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >who makes a good (yet still, hopefully, inexpensive) crank arm? As[/color]
[color=blue]> the[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >terrain is quite flat around here, I'm probably looking at a 6" size.[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >I borrowed the crank arms from my Coker because they were the right[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >length. I really should have thought that through before I took them[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >into the woods. I had to make a 6" jump up to a bridge, and I landed[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >just hard enough to bend one crank to the point where I could feel,[/color]
[color=blue]> but[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >not see the bend. Well, after that, I figured it wouldn't make much[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >difference if I went for a 3' drop.=20[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >http://www.rit.edu/~jvl2957/bent_crank.jpg[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >That drop had the oddest feel -- I felt the shock of the landing as[/color]
[color=blue]> it[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >was absorbed by the pedal... which, unlike other drops I've made on[/color]
[color=blue]> my[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >20" uni, did not apply any of that force back to my foot.[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >Also learned that day, riding a mile on a dirt trail with two bent[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >cranks can be interesting.[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >Jeff Lutkus[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >_____________________________________________________________[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor3}]> > >Free e-Mail and Webspace - http://Unicyclist.com[/color]
[color={usenetquotecolor2}]> >[/color]
[color={usenetquotecolor2}]> > _____________________________________________________________[/color]
[color={usenetquotecolor2}]> > Free e-Mail and Webspace - http://Unicyclist.com[/color]
[color=blue]>[/color]
[color=blue]>[/color]
[color=blue]> __________________________________________________[/color]
[color=blue]> Do You Yahoo!? Get personalized email addresses from Yahoo! Mail[/color]
[color=blue]> http://personal.mail.yahoo.com/[/color]

__________________________________________________
Do You Yahoo!? Get personalized email addresses from Yahoo! Mail
http://personal.mail.yahoo.com/

[color=blue]> The Profile cranks are one-piece through this area (no welds). I think[/color]
[color=blue]> this makes them stronger although they still seem to brake occasionally[/color]
[color=blue]> in this high stress area. I've never had a problem though, and in any[/color]
[color=blue]> case this would be a warranty issue.[/color]

The Profiles that I broke underwent considerable plastic deformation (5
degrees, maybe?) before breaking. Examining the break area, it broke on a
45, like a vee shape, which I believe indicates it did not fail due to
fatigue. Anyway, I don't blame it on being a defect or anything, I just
gave them too much.

Chris