|   What's the best chain? | DSC
Dec 15, 2002 10:14 AM | | Hey everyone. I've been having a blast up here in Pisgah this fall, it makes the old home trails seem piddlely in comparison. Anyway, I'm in the market for a new chain (mine broak twice in a ride at Dupont, probably becuase I put the originol pin back in when I was took it off last time), but there are a lot of choices. I deffinitely want somehting with a powerlink, so was thinking of just going for SRAM, but are there better options? As far as SRAM chains go, is the PC-99 really much better than the PC-69? Corrosion resistance is pretty important in a chain for me: it's really wet and muddy here most of the time. Strength is probably not as big an issue, as I weigh about 160 and take care not to shift while crankin hard on climbs.
Any chain opinions or advice is welcome!
Thanks,
D |
| Definately the SRAM.... | Cook
Dec 15, 2002 11:46 AM | | I always buy the 69....cause it's cheaper and I try to change my chains about twice a year regardless, so I don't want to be coughing up large sums.
It gets pretty wet and sloppy here in SW Ontario also (spring & fall)....I've never had a problem. Never had a chain (or powerlink) fail.
Cheers |
| 2nd, 3rd and 4th the SRAM ... | Philber
Dec 15, 2002 12:05 PM | | ... and I think the 99 has more plating on the outside, so it would probably be less corrosive. But like Cook says, you should be replacing your chain before it corrodes anyways. I use the 69's to save $$, and they work just fine. The powerlink is nothing short of essential, and it is an absolute wonder to me that people still buy Shimano chains. Why?
BTW, if your chain has broken twice on you and it's old, prepare yourself to be buying new cogs and maybe chain rings too. Basically, if the chain's a couple of seasons old and it's on a bike that's used regularly in adverse conditions, chances are good the cogs are shot and maybe the rings (or the most popular one) is shot. If the teeth on your gears are hook-shaped, or shark fin-shaped, they're done. In muddy or otherwise crappy conditions, change your chain every 500 miles or so - it's great preventive medicine. |
| Another vote for SRAM. nm | Rozonic Man
Dec 15, 2002 1:11 PM | | nm |
| PC-59 | seeker333
Dec 15, 2002 3:34 PM | | SRAM PC-59, $14 at jenson. i've been using these for a couple years with no problems. I've wondered if those fancier SRAM models were really worth the extra expense, in terms of performance or longetivity. Any comments? |
| I don't hold any mistaken impressions... | næstep
Dec 15, 2002 4:32 PM | | ...that the PC-59 is somehow stronger than the PC-99, or that it measures up to the legendary strength of the Rohloff SLT chains, but I, too, have been running PC-59s for years now without a single breakage or any corrosion problems to speak of. So from that standpoint, the -59 has simply proven "good enough" for my use.
næstep |
| thanks i feel more justified in my frugality now, ..... | seeker333
Dec 15, 2002 8:14 PM | | and that $10 i saved on the chain goes straight into my Rohloff speedhub savings account - so at this rate i may be able to afford one in say, 25-50 years |
| What you need is deficit spending... | næstep
Dec 16, 2002 8:25 AM | | Ongoing derailleur drivetrain maintenance is going to eat up all your Speedhub savings a cassette here, a new derailleur there, the occasional chainring and, of course, at least 4x the chain wear rate versus the non-shifting, perfect chainline of the Speedhub.
This makes a justifiable case for deficit spending to pull you out of the neverending downward sprial of drivetrain maintenance. Long live micro-Reaganomics!
næstep |
| PC-99 has PUSH POWER of 2000N (450in/lbs), PC-59 1500N (340in/lbs)... | clary.
Dec 15, 2002 8:58 PM | | while both chains have a tensile strength of 9800N (2200in/lbs) and both weigh the same at 300grams.
I use PC-58 (8 speed) and PC-59 (9 speed) because I am a spinner and wear out chains rather than break them, so a stronger chain (and more expensive chain) is of no advantage to me.
PC-58 (8 speed) has PUSH POWER of 1500N (340in/lbs), a tensile strength of 9800N (2200in/lbs), and a weight of 315 grams.
PC-68 (8 speed) has PUSH POWER of 2000N (450in/lbs), a tensile strength of 9800N (2200in/lbs), and a weight of 315 grams. |
| What's "PUSH POWER"? | tl1
Dec 16, 2002 4:09 AM | | Doesn't a chain pull to move you? |
| Sram's expression for Torque (expressed in Newtons or in/lbs) nm | clary.
Dec 16, 2002 8:09 AM | | |
| what are you talking about? | third day
Dec 16, 2002 10:13 AM | | Newtons and "Inches per pound" (in/lbs) are not equivalent, not are they units of torque. Do you mean N*m and in*lb ?
And what type of torque does a chain experience anyway? Please enlighten me. |
| in*lbs, ft*lbs (spoken and mathematical) same as in/lbs, ft/lbs(written)... | clary.
Dec 16, 2002 1:15 PM | | Torque
Torque is defined as the force at any one point on the edge of a circle in the exact direction of the rotation multiplied by the radius (distance from the center). This comes from the calculus/geometry concept of a "tangent", a line which touches exactly one point of the edge of a circle.
In the metric system, force is calculated in newtons, and distance is in meters, so the standard torque unit is Newton-Meters or N-M. In the Standard/English system, force is calculated in pounds and distance in feet. So the torque unit is lb-ft, usually pronounced as "Foot-pounds" and sometimes written as "ft/lb".
Unfortunately, in this case, SRAM gives a value for Force and not Torque. (the error is in the data where SRAM mixes force and torque values of N and in*lbs. You are right that it should be either N and lbs or N*M and ft*lbs. When SRAM called it PUSH POWER, I assumed they were testing something to do with torque (HorsePower=torque * rpm) and ignored the N for force and assumed they meant the ft*lbs for torque. 2000N of force converts to 449.617886 lbs(as PDF value of 450) but 450in*lbs converts to 50.84N*M (which is not the PDF value). So SRAM meant Force and not torque.
Force, torque (force * distance), power (torque * time) are all related and can be measured in their relevancy.
Rear hub clutches are tested for torque (Chris King's patented Ring Drive system boasts a torque tolerance of over 800 ft/lb). So if you put a chain in a rear cog, and torqued the cog until the chain broke, you would be able to obtain a torque tolerance for the chain being tested.
Here is a screen print of a PDF with the SRAM data: |
| that's ridiculous | third day
Dec 16, 2002 2:26 PM | | "So if you put a chain in a rear cog, and torqued the cog until the chain broke, you would be able to obtain a torque tolerance for the chain being tested. "
That doesn't make sense at all. There would be no logical reason to measure chain strength in this way. You could certainly create some torque this way, but how that torque relates to the chain is irrelevant. The amount of torque could be anything you wanted it to be, depending on the length of the "lever arm". What if you wrapped one chain around a pencil and another chain around a tractor tire. The much larger radius of the tractor tire would enable you to generate much more torque, but the force required to break chain would be the same in both cases. There is no logical reason to refer to chain strength in units of torque. |
| No. The 800ft/lbs of torque tolerance the CK hub measures... | clary.
Dec 16, 2002 3:40 PM | | is equal to 800lbs of force applied at 1 ft. The same test can be done for the chain. Fix the chain on the ground, extend it around the cog and test the torque required to break the chain. You will get a force value at 1 ft. for the chain which will be the torque tolerance for the chain.
If the chains were tested in this manner, you would know their relative strength compared to hubs.
What is the point in knowing that the CK hub has a torque tolerance of 800ft/lbs and that the chain has a force tolerance of 450lbs. If you are comparing apples and oranges, which one will fail first? |
| Are you serious or are you just having fun. | third day
Dec 16, 2002 7:08 PM | | What is the point in knowing that the CK hub has a torque tolerance of 800ft/lbs and that the chain has a force tolerance of 450lbs. If you are comparing apples and oranges, which one will fail first?
Simple. Just measure the radius of the gear that the chain is engaged to, and multiply by the force on the chain. Torque = Force*distance. If this number exceeds the allowable torque of the hub, the hub will break, and vice versa.
Surely you know that, based on your thorough description of torque in your post above. Or are you just screwing with me? |
| I still can't figure out what "push power" is | third day
Dec 16, 2002 7:15 PM | | I have never heard of "push power" before. Does anyone know what the heck SRAM is talking about? Maybe it's the force required to push out one of the pins. 340 lbs seems kind of high, but it could be... |
| PUSH POWER is their catch phrase for Force measured in Newtons or lbs, | clary.
Dec 16, 2002 9:16 PM | | so PC-99 is capable of a Force of 2000N(450lbs) upon it.
You have to delete all reference to "in/" in that chart since after doing conversions, the numbers make sense only when they represent Force and not Torque.
It's probably the Force required to destroy the chain. So hang up to 450lbs on the end of a chain hanging from the rafters before it will damage. |
| I think you're thinking of Tensile Strength | third day
Dec 17, 2002 6:04 AM | | In your rafter-hanging example, I am absolutely sure the chain wouldn't break under only 450 lbs. I weigh about 200 lbs and therefore I could quite easily put 450 lb of tensile force on a chain using my 175mm cranks with the chain on the small chainring.
Tensile strength is given as 2200lb, which seems reasonable for your rafter-hanging example.
I think Push Power must be referring to something else.
Where did you find that chart, by the way? I couldn't find it on SRAM's website. |
| The differences in the chains are in the way the pins are riveted... | clary.
Dec 17, 2002 7:19 AM | | with the PC-99 being Cross-Step Riveted and the other chains being Step Riveted only. I imagine that the PUSH POWER is related to that difference and other mechanical construction differences and that the Tensile Strength, which is the same for all chains, is related to the metal being used. Could also be that those numbers are not for breakage but for effectiveness. So after 450lbs, the chain looses it's mechanical effectiveness to function as specified.
Here is where I found the PDF:
http://www.zem.ch/en/hub_gears_en.pdf
The chain data is on page 54. |
| That's weird.. I find that I do all the pushing, not my PC-99 | Locoman
Dec 16, 2002 6:04 AM | | Maybe I bought a lazy chain? |
| If you can push PC-99 to the max, you're still worth less than a horse... | clary.
Dec 16, 2002 8:40 AM | | torque * rpm
------------------- = horsepower
5252
450in/lbs /12 = 37.5ft/lbs
37.5ft/lbs * 100rpm
----------------------------- = .71HP
5252
(that's if you could maintain 100 rpm and equal the chain torque) |
| Sram PC89 road chain works great | Duckman
Dec 15, 2002 7:09 PM | | and have never broken one...yet. |
| PC89 has a PUSH POWER of 1500N (340 in/lbs) at 295 grams. nm | clary.
Dec 15, 2002 9:01 PM | | |
| re: What's the best chain? | FireHawk
Dec 15, 2002 8:02 PM | | Sram 69 is great. Have a 2002 Giant NRS-2 that was notorious for ghost shifting. Tried everything recommended but nothing worked. Finally, was told to change the chain. That was the answer. Went from a Shimano HG to a Sram 69. The bike no longer ghost shifts. The chain is such an unbelieveable and effective link to the transmission of power. You do not want a chain that ghost shifts. Sram is the answer. |
| There was a Giant advisory on NRS shifting | tl1
Dec 16, 2002 4:12 AM | | From Angry Asian's site:
http://www.angryasian.com/main.cfm
Attn: all Giant NRS owners!!! Posted By: AngryAsian
There seems to be a fair number of people out there who are having skipping problems on the rear end of their Giant NRS. Chances are, I'm assuming you likely have a '02 frame and are running 9 speed with a Shimano rear derailleur, no? Anyway, here's the explanation and the fix:
Under hard pedaling torque, the seatstay is actually bowing just a bit. When that happens, the cable stops that are on the seatstay are moving slightly closer together. The effect of this is that the cable tension drops just a hair, but enough to move the derailleur a bit, causing the skipping. Note that this is also why SRAM ESP users and those running 8spd are not affected (the ESP system requires significantly more cable movement to actuate the derailleur, and 8spd cogs are spaced further apart). Also, the dropout design of the '01 frame didn't allow for quite as much frame deflection in that plane. Anyway, the fix is amazingly simple: just run a single piece of derailleur housing from the rearmost cable stop on the top tube down to the derailleur. Essentially, you are just bypassing the cable stops on the seatstay and taking the flex out of the equation. You'll have to zip-tie the housing to the stay so it may not be as pretty, but at least your drivetrain won't skip anymore! Anyway, hope that removes some frustration from your ride, and please pass the word to other NRS owners!
Oh, and thanks to Steve at Giant for providing me with some key bits so that I could figure this out, once and for all! |
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