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#1
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Cranks that can handle a wide range of chain rings
I have been in Colorado for much of this winter and I do not have my
own bikes with me. I have used solo Campagnolo forever (1985 anyway) on my own bikes and I was thinking of picking up 1 or 2 compact cranksets for use on these trips to the Colorado mountain road rides. I have used 39/53 doubles and a triple (that was geared too low) and I think a 34 to 36 with a 50 would be perfect for these trips. Now that I am getting serious about it, I wonder if this is the best idea (swapping cranks several times a year on a Campagnolo bottom bracket. Am I likely to run in to problems from swapping them freguently (like wearing out the crank's bottom bracket interface enough to cause creaking)? I remember that at least one French manufacturer (Mavic) had a crank that could be changed from a double to a triple. I think Stronglight might even still make a crank that can accomplish this. Would this be a better idea? I guess I could get a dedicated bike for doing "nothing but" climbing and descending. The final idea is just to go with compact and leave them there but use one that can handle a 52 big ring. I think FSA ships at least one of its compact cranks with a 36/52. As long as I keep the tooth difference at 16 ir fewer I should be ok. Does anyone have any experince with these compacts swapping rings of these sizes? |
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#2
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Chris M wrote: I remember that at least one French manufacturer (Mavic) had a crank that could be changed from a double to a triple. I think Stronglight might even still make a crank that can accomplish this. Would this be a better idea? I guess I could get a dedicated bike for doing "nothing but" climbing and descending. The final idea is just to go with compact and leave them there but use one that can handle a 52 big ring. I think FSA ships at least one of its compact cranks with a 36/52. As long as I keep the tooth difference at 16 ir fewer I should be ok. Does anyone have any experince with these compacts swapping rings of these sizes? "Compact" cranks that use a 110mm bolt circle will accept chainrings from 33 teeth on up. The largest I could find in a 10-second search is 73 teeth. A 34-52 should be fine, but the shifting may not be as good as (for instance) a 39-53. What front derailleur and shifter are you planning on using? Another equipment-specific issue occurs if you use the small chainring-smaller cog gears. You may get some rub on the larger chainring due to the extreme angle on the chain. This will be less apparent on bikes with longer chainstays. Almost any triple crank can be used as a double, just by removing the inner chainring. Jeff |
#3
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Chris M wrote:
I have been in Colorado for much of this winter and I do not have my own bikes with me. I have used solo Campagnolo forever (1985 anyway) on my own bikes and I was thinking of picking up 1 or 2 compact cranksets for use on these trips to the Colorado mountain road rides. I have used 39/53 doubles and a triple (that was geared too low) and I think a 34 to 36 with a 50 would be perfect for these trips. Now that I am getting serious about it, I wonder if this is the best idea (swapping cranks several times a year on a Campagnolo bottom bracket. Am I likely to run in to problems from swapping them freguently (like wearing out the crank's bottom bracket interface enough to cause creaking)? I remember that at least one French manufacturer (Mavic) had a crank that could be changed from a double to a triple. I think Stronglight might even still make a crank that can accomplish this. Would this be a better idea? I guess I could get a dedicated bike for doing "nothing but" climbing and descending. The final idea is just to go with compact and leave them there but use one that can handle a 52 big ring. I think FSA ships at least one of its compact cranks with a 36/52. As long as I keep the tooth difference at 16 ir fewer I should be ok. Does anyone have any experince with these compacts swapping rings of these sizes? The 'triplizer' or 'mertz conversion' type rings are available . Removing/remounting crank arms on your spindle twice a year will kill them in a few seasons. Either dedicate one bike for this or get the 'triplizer' setup or simply go triple and just don't shift to the lower range when you're on the prairie! Modern triples perform very well, not at all like the finicky stuff of the classic era! -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971 |
#4
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On Mon, 28 Feb 2005 17:07:23 -0600, A Muzi
wrote: Removing/remounting crank arms on your spindle twice a year will kill them in a few seasons. Can you say more about this? Is there a certain number of times that a square taper crank can be remounted before it is unusable? How do you tell? I swap parts around, try different setups, etc. This can include cranks. I have an old Sugino crankset that has probably been remounted 6-8 times, moving from one frame to another and back, off for a repaint then back on, etc. This seems like it might fall within your 'few seasons' limit of remounts (obviously time is not the factor but number of remounts; aluminum won't 'heal' or reform if the remount happens every six months or every six years). |
#5
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On 28 Feb 2005 11:50:42 -0800, "Chris M"
wrote: I have been in Colorado for much of this winter and I do not have my own bikes with me. I have used solo Campagnolo forever (1985 anyway) on my own bikes and I was thinking of picking up 1 or 2 compact cranksets for use on these trips to the Colorado mountain road rides. I have used 39/53 doubles and a triple (that was geared too low) and I think a 34 to 36 with a 50 would be perfect for these trips. Now that I am getting serious about it, I wonder if this is the best idea (swapping cranks several times a year on a Campagnolo bottom bracket. Am I likely to run in to problems from swapping them freguently (like wearing out the crank's bottom bracket interface enough to cause creaking)? I remember that at least one French manufacturer (Mavic) had a crank that could be changed from a double to a triple. I think Stronglight might even still make a crank that can accomplish this. Would this be a better idea? I guess I could get a dedicated bike for doing "nothing but" climbing and descending. The final idea is just to go with compact and leave them there but use one that can handle a 52 big ring. I think FSA ships at least one of its compact cranks with a 36/52. As long as I keep the tooth difference at 16 ir fewer I should be ok. Does anyone have any experince with these compacts swapping rings of these sizes? In my personal experience, once I started with compact cranks, which is before the boom after use in TdF, I had no need for 53/39 or 'standard ring' double cranks. You certainly can get 52/36 and swap in a 34t ring when you need it. Yes, 52/34 will work but you'l be using the the outer and inner cogs more. If your bottom bracket is a Centaur or other Campy 111 or 115, you can buy a Sugino XD and just mount the arms on your bb. If you have a Chorus or Record bb, you'll be looking for a bb or the Campy compact cranks. I avoid removing crankarms as much as I can. A 110 bolt pattern is much more versatile than 135 or 130. You have a wide choice of chainring sized from in the 50s down to 33. I run my tandem with a 50/34 and 12/34 XT cassette. I've given up on triples. Wanna buy a Racing-T? |
#6
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-----BEGIN PGP SIGNED MESSAGE-----
In article , Dan Daniel wrote: On Mon, 28 Feb 2005 17:07:23 -0600, A Muzi wrote: Removing/remounting crank arms on your spindle twice a year will kill them in a few seasons. _ Is there something different about modern cranks? In the era before cartridge bearing BB's it was common practice to clean and lube the BB twice a year. This required removing the cranks. _ Booker C. Bense -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBQiSVEWTWTAjn5N/lAQFVqwP/XgHDX3sbmuEmR9E+DHRoSemWsfyM9mCA aPrE20xou3UdBfUpn15AzkDMSFLybCUFDRF7Ie/qSQhUpkPxm/o6AaeSfyus+Fsa l6a5tUmwqKjEuaAVg6GpwHaMuKjjsfpfSTaCtDzo2KUvC0hDF2 8/5+G6ysNur9H/ k9rtXocRxWE= =Q5Rg -----END PGP SIGNATURE----- |
#7
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Dan Daniel wrote:
On Mon, 28 Feb 2005 17:07:23 -0600, A Muzi wrote: Removing/remounting crank arms on your spindle twice a year will kill them in a few seasons. Can you say more about this? Is there a certain number of times that a square taper crank can be remounted before it is unusable? How do you tell? I swap parts around, try different setups, etc. This can include cranks. I have a folding travel bike on which I remove the cranks (Shimano 105) every time I pack it in its suitcase. They've been removed and reinstalled dozens of times over the last 10 years with no apparent harm. |
#8
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On Mon, 28 Feb 2005 17:07:23 -0600, A Muzi
wrote: Removing/remounting crank arms on your spindle twice a year will kill them in a few seasons. Dan Daniel wrote: Can you say more about this? Is there a certain number of times that a square taper crank can be remounted before it is unusable? How do you tell? I swap parts around, try different setups, etc. This can include cranks. I have an old Sugino crankset that has probably been remounted 6-8 times, moving from one frame to another and back, off for a repaint then back on, etc. This seems like it might fall within your 'few seasons' limit of remounts (obviously time is not the factor but number of remounts; aluminum won't 'heal' or reform if the remount happens every six months or every six years). I don't know. At least as far as a hard number. And the range is wide. If the OP can reasonably structure this such that he won't have to remove/remount a crank arm every few months that would be a better choice. Various riders mount various cranks with extremely low and some with extremely high torque. With and without lube. (Shoot for something around 40-50 kcm. I lube everything.) Too many variables to say "five times" or "twenty six times" or any number as a 'rule'. Some riders continually tighten their cranks, walking them up the taper to death. Sure, you know not to do that. But changing them every once in a while is the same thing, isn't it? -- Andrew Muzi www.yellowjersey.org Open every day since 1 April, 1971 |
#9
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On Tue, 01 Mar 2005 18:00:53 -0600, A Muzi
wrote: On Mon, 28 Feb 2005 17:07:23 -0600, A Muzi wrote: Removing/remounting crank arms on your spindle twice a year will kill them in a few seasons. Dan Daniel wrote: Can you say more about this? Is there a certain number of times that a square taper crank can be remounted before it is unusable? How do you tell? I swap parts around, try different setups, etc. This can include cranks. I have an old Sugino crankset that has probably been remounted 6-8 times, moving from one frame to another and back, off for a repaint then back on, etc. This seems like it might fall within your 'few seasons' limit of remounts (obviously time is not the factor but number of remounts; aluminum won't 'heal' or reform if the remount happens every six months or every six years). I don't know. At least as far as a hard number. And the range is wide. If the OP can reasonably structure this such that he won't have to remove/remount a crank arm every few months that would be a better choice. Various riders mount various cranks with extremely low and some with extremely high torque. With and without lube. (Shoot for something around 40-50 kcm. I lube everything.) Too many variables to say "five times" or "twenty six times" or any number as a 'rule'. Understood. When you said that remounting twice a year would lead to failure in 'a few' seasons, that made me wonder if you personally *do* have some specific number or range in your own practice. Some riders continually tighten their cranks, walking them up the taper to death. Sure, you know not to do that. But changing them every once in a while is the same thing, isn't it? I am not arguing that mounting cranks is potentially destructive (although not to the point of failure every time, obviously). And whatever the 'destruction' at each remounting, it will be cumulative. The crank will not bounce back to its original shape. I don't work in a bike shop, and even though I was working on bikes before your shop opened, my total wrenching time over my life is probably less than you've done in a few weeks of your business. Is there some way to tell if a crank is in trouble? I have a very specific reason for asking- last spring I remounted some cranks after a repaint, and they would not work with the same bottom bracket as before. I needed to use a longer BB- from a 122 to a 127. With the old BB, the small chainring (Sugino triple, 10 years old or more) wouldn't clear the chainstay. At the time, I attributed this to the alignment work that had been done on the frame before the repaint. There had been some serious rear alignment problems since I bought the frame (used), and it seemed like a good time to get it looked at. The whole rear triangle had to be twisted, shifted and realigned a couple of millimeters (cold set by Bernie Mikkelsen, a very good frame builder by reputation). I have had no hints of any problems since the rebuild. But your comments here have me wondering if the crank is in trouble. |
#10
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On Tue, 01 Mar 2005 18:00:53 -0600, A Muzi
wrote: On Mon, 28 Feb 2005 17:07:23 -0600, A Muzi wrote: Removing/remounting crank arms on your spindle twice a year will kill them in a few seasons. Dan Daniel wrote: Can you say more about this? Is there a certain number of times that a square taper crank can be remounted before it is unusable? How do you tell? I swap parts around, try different setups, etc. This can include cranks. I have an old Sugino crankset that has probably been remounted 6-8 times, moving from one frame to another and back, off for a repaint then back on, etc. This seems like it might fall within your 'few seasons' limit of remounts (obviously time is not the factor but number of remounts; aluminum won't 'heal' or reform if the remount happens every six months or every six years). I don't know. At least as far as a hard number. And the range is wide. If the OP can reasonably structure this such that he won't have to remove/remount a crank arm every few months that would be a better choice. Various riders mount various cranks with extremely low and some with extremely high torque. With and without lube. (Shoot for something around 40-50 kcm. I lube everything.) Too many variables to say "five times" or "twenty six times" or any number as a 'rule'. Some riders continually tighten their cranks, walking them up the taper to death. Sure, you know not to do that. But changing them every once in a while is the same thing, isn't it? Searching rec.bicycles.tech for "Repeatedly mounting and removing cranks" yielded a post that reports measurements, as well as the following summary: "Repeatedly mounting and removing these cranks during my test caused them to fit farther onto the spindle each time." Here's the rest of the original post: http://groups-beta.google.com/group/...1e1f0b34335f72 Newsgroups: rec.bicycles.tech From: (Rinards) Date: 1997/09/15 Subject: greased cranks slip farther up the tapers There is much debate about whether one should grease the fit between the crank spindle and the square tapered hole in the crank or not. I recently found a cracked crank on my bike and became curious about the effects of greasing the tapers. So I made some measurements of how far a crank slips up the taper on a bottom bracket spindle when the tapers are greased compared to when the grease is wiped off. TEST METHOD I measured seven cranks: the left and right arms of three crank sets, and one loose right hand arm I had lying around. The cranks were a pair of old, used Nuovo Record cranks, a new pair of Dura-Ace FC-7402 cranks, a new pair of Ofmega Super Competitzione arms, and an NOS Sugino “2 GC” melt forged arm. During the course of my test I mounted all the cranks dry, then mounted them greased, then wiped them off and mounted them all dry again. I measured the cranks’ position before tightening them and after. I used the same spindle and bolt for all cranks. I mounted the cranks the same orientation on the spindle each time. I used a cheap torque wrench to determine when I got to 300 in*lb. I greased the bolt’s threads and washer. EFFECT ON HOW FAR THE CRANK SLIPS UP THE TAPER On average, cranks mounted on a dry spindle slide about 2.2 mm up the taper. That’s starting from finger tight and ending at 300 inch pounds. However, the same cranks, when mounted on greased tapers, slide 3.1 mm up the taper on average. That’s about 40% farther up the taper when greased than dry. Since the crank slips farther up the taper, it must be straining more after installation on a greased spindle. It appears greasing the tapers of your bottom bracket spindle increases the stress on your crank’s square tapered hole. EFFECT ON PREDICTING CHAINLINE Reducing the stress on the square tapered hole is one apparent benefit of mounting the cranks dry. Another benefit is more accuracy predicting chainline, too. As I said above, cranks mounted dry slip 2.2mm up the taper on average. Of the seven cranks I measured, some slipped farther and some slipped less. During the first dry mounting, the most any crank slipped up the taper was 2.7mm, and the least any crank slipped was 1.8mm. This range is only 0.9mm. During the second dry mounting, the range was even less: 0.7mm. In contrast, when mounted on a greased spindle, there was a wider range of how far the crank would slip up the taper. The farthest any crank slipped was 3.6mm, and the least a crank slipped was 2.4mm, for a range of 1.1mm. That’s 20 to 57% more spread than when the cranks were mounted dry. I admit that's a pretty small difference, but one that bothers the perfectionist in me when I am trying to choose a spindle to give a desired chainline. It is harder to predict what chainline you’ll get if you mount your cranks with grease on the tapers. EFFECT ON “STRETCHING” THE CRANK’S SQUARE HOLE Repeatedly mounting and removing these cranks during my test caused them to fit farther onto the spindle each time. They did not go back to where they were the first time, even when the grease was wiped off and the cranks were mounted dry again. I recorded the position of each crank after mounting it the first time (dry). Then I recorded the position of each crank after mounting it the second time (greased). On average, the final resting place was 1.1mm farther on the spindle when mounted the second time (with grease) compared to the first time (dry). After wiping off the grease and re-mounting the cranks a third time (dry), they still ended up 0.6mm farther up the taper than they did the first time, though they did recover somewhat from the greased position. I do not know why the cranks ended up farther on the spindle after each time. I don’t know if the cranks were stretched once by mounting them with grease, or if the fit gets looser even from mounting them dry. Someday I may get around to measuring the cranks’ position after repeated dry mountings to find out. But probably I won’t. HOW I PLAN TO MOUNT MY CRANKS IN THE FUTURE I will wipe off the spindle and the square tapered hole in the crank with a rag, and mount the cranks dry. I will carefully wipe off the threads of the bolt, grease them, the bolt’s shoulder and the washer. I will torque the bolt to 300 in*lb. I will take my cranks off as seldom as possible. Damon Rinard |
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