Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Fifty Plus (50+) Share the victories, challenges, successes and special concerns of bicyclists 50 and older. Especially useful for those entering or reentering bicycling.

Reply
 
Thread Tools Search this Thread
Old 06-28-07, 08:58 PM   #1
tlc20010
The Grampster
Thread Starter
 
tlc20010's Avatar
 
Join Date: Sep 2005
Location: Washington, DC
Bikes: Eddy Merckx SXM, LeMond Buenos Aires, Cannondale Road Warrior 1000 plus a couple of comforts (Specialized Crossroads and Giant Cyprus) and a beater mtb for around town.
Posts: 657
Sort of technical question

Okay, an actual bike question. One of my bikes has a Shimano FC-R700 compact crank with 172.5 mm crank arms and I might be interested in trying a shorter crank. Do I have to buy a whole new crank set or can I get just the sorter arms--and from where and is it easier (and/or cheaper) than getting a new crank set??
__________________
The definition of insanity is doing the same thing over and over and expecting different results.
--Ben Franklin
tlc20010 is offline   Reply With Quote
Old 06-28-07, 09:01 PM   #2
Jet Travis
Ride Daddy Ride
 
Jet Travis's Avatar
 
Join Date: Feb 2007
Location: Villa Incognito
Bikes: 1983 Trek 720; 1983 Trek 620; 1989 Gi Cannondale Bad Boy Ultra; LeMond Victoire; Bike Friday Pocket Rocket Pro
Posts: 2,648
I fear you must get a new crankset.
__________________
"Light it up, Popo." --Levi Leipheimer
Jet Travis is offline   Reply With Quote
Old 06-28-07, 09:03 PM   #3
BSLeVan
Senior Member
 
Join Date: Feb 2007
Location: S.E. Pennsylvania, USA
Bikes:
Posts: 1,737
You'll need the whole crankset. The drive side arm is attached to the spider arms to which the chainrings are connected.
BSLeVan is offline   Reply With Quote
Old 06-28-07, 09:53 PM   #4
Tom Bombadil
His Brain is Gone!
 
Tom Bombadil's Avatar
 
Join Date: Sep 2006
Location: Paoli, Wisconsin
Bikes: RANS Stratus, Bridgestone CB-1, Trek 7600, Sun EZ-Rider AX, Fuji Absolute 1.0, Cayne Rambler 3
Posts: 9,980
I sure wish it was easier. I'd love to try 165mm crank arms. All of my bikes presently have 170mm.

Technically a 172.5mm arm should suffice unless your inseam is less than around 31".
Tom Bombadil is offline   Reply With Quote
Old 06-28-07, 09:55 PM   #5
John E
feros ferio
 
John E's Avatar
 
Join Date: Jul 2000
Location: www.ci.encinitas.ca.us
Bikes: 1959 Capo; 1980 Peugeot PKN-10; 1981 Bianchi; 1988 Schwinn KOM-10;
Posts: 16,814
Just swap the cranks themselves. You can reuse your bottom bracket, pedals, and chainrings. With luck, you might even find someone with whom to trade cranks.
__________________
"Early to bed, early to rise. Work like hell, and advertise." -- George Stahlman
Capo [dschaw'-poe]: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger, S/N 42624
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1981 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069
John E is offline   Reply With Quote
Old 06-28-07, 10:15 PM   #6
BluesDawg
just keep riding
 
BluesDawg's Avatar
 
Join Date: Feb 2005
Location: Milledgeville, Georgia
Bikes: 2015 Specialized AWOL Comp frameset (custom build), 2015 Zukas custom road, 2014 Specialized Crave Pro 29, 2003 KHS Milano Tandem, 1986 Nishiki Cadence rigid MTB, 1980ish Fuji S-12S
Posts: 13,190
Theoretically you could take the spider and rigs off of your current arm and replace just the arms. But in reality you will not likely be able to find the arms for lass than a whole crankset. Replacing a crankset is a 5 to 10 minute job. You won't even need a crank puller for the FC-R700.
http://www.parktool.com/repair/readh...id=122#shimano
BluesDawg is offline   Reply With Quote
Old 06-29-07, 12:09 PM   #7
stapfam
Time for a change.
 
stapfam's Avatar
 
Join Date: Jan 2004
Location: 6 miles inland from the coast of Sussex, in the South East of England
Bikes: Dale MT2000. Bianchi FS920 Kona Explosif. Giant TCR C. Boreas Ignis. Pinarello Fp Uno.
Posts: 19,915
Now just a change of crankset and you may be lucky---BUT-- In my experience- even if you have the same type of bottom bracket (Splined or square Etc. ) You may need a different length bottom bracket. Found this a lot on the MTB's where you do an upgrade that is many grades of up. Shimano LX up to XT was fine as there was only 2mm difference but Once had to change a Cheap OE fitment to Deore and the Deore required a BB of 115 mm and the OE had a BB of 127mm. Didn't matter that much as The BB was shot- but just a warning that you may have to change the BB aswell.
__________________
How long was I in the army? Five foot seven.


Spike Milligan
stapfam is offline   Reply With Quote
Old 06-29-07, 01:16 PM   #8
BluesDawg
just keep riding
 
BluesDawg's Avatar
 
Join Date: Feb 2005
Location: Milledgeville, Georgia
Bikes: 2015 Specialized AWOL Comp frameset (custom build), 2015 Zukas custom road, 2014 Specialized Crave Pro 29, 2003 KHS Milano Tandem, 1986 Nishiki Cadence rigid MTB, 1980ish Fuji S-12S
Posts: 13,190
Quote:
Originally Posted by stapfam
Now just a change of crankset and you may be lucky---BUT-- In my experience- even if you have the same type of bottom bracket (Splined or square Etc. ) You may need a different length bottom bracket. Found this a lot on the MTB's where you do an upgrade that is many grades of up. Shimano LX up to XT was fine as there was only 2mm difference but Once had to change a Cheap OE fitment to Deore and the Deore required a BB of 115 mm and the OE had a BB of 127mm. Didn't matter that much as The BB was shot- but just a warning that you may have to change the BB aswell.
I think most of us are assuming he would be changing to a longer arm crank of the same model as the original, not an upgrade. At least that is what I took him to mean.
BluesDawg is offline   Reply With Quote
Old 06-29-07, 01:17 PM   #9
ThinLine
Senior Member
 
Join Date: May 2007
Location: Pennsylvania
Bikes: Basso, Tommaso, Ibex, Schwinn, SWOBO, Trek
Posts: 1,942
Bummer!
ThinLine is offline   Reply With Quote
Old 06-29-07, 01:25 PM   #10
Tom Bombadil
His Brain is Gone!
 
Tom Bombadil's Avatar
 
Join Date: Sep 2006
Location: Paoli, Wisconsin
Bikes: RANS Stratus, Bridgestone CB-1, Trek 7600, Sun EZ-Rider AX, Fuji Absolute 1.0, Cayne Rambler 3
Posts: 9,980
Quote:
Originally Posted by tlc20010
Okay, an actual bike question. One of my bikes has a Shimano FC-R700 compact crank with 172.5 mm crank arms and I might be interested in trying a shorter crank.
Pricey crankset.

W/170mm crank arms:
http://www.niagaracycle.com/product_...oducts_id=6755

w/165mm crank arms:
http://www.niagaracycle.com/product_...oducts_id=6754
__________________
"Too often I would hear men boast of the miles covered that day, rarely of what they had seen." Louis L'Amour

There are two types of road bikers: bikers who are faster than me, and me. Bruce Cameron - Denver Post
Tom Bombadil is offline   Reply With Quote
Old 06-29-07, 01:45 PM   #11
RockyMtnMerlin
Senior Member
 
RockyMtnMerlin's Avatar
 
Join Date: Sep 2005
Location: Laramie Wyoming
Bikes: Merlin Extralight Topolino Wheels Campy Record
Posts: 2,970
Quote:
Originally Posted by Tom Bombadil
No. THIS http://fairwheelbikes.com/index.php?...products_id=64 is a pricey crankset. Only about $1,000 additional dollars!
RockyMtnMerlin is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 12:11 AM.