SRAM Flat Top chains

[Mikerb]

I have SRAM Transmission obviously including a flat top chain. So how are you guys checking chain wear??
I have read conflicting information and some that makes little sense to me!!

SRAM appear to recommend changing chain at 0.8% wear as tested with either a stupidly expensive SRAM chain checker or a Pedro chain checker, yet both appear no different from any other chain checker.
I have also read that mechs at SRAM training workshops have been told to just run both chain and cassette until gear change is no longer working well and then change both together.

The only difference between the flat tops and any other 12 speed chain as far as I can see is that whilst the pitch remains at 1/2 inch/12.5 mm, the rollers have a larger OD. The difference being 7.72mm as opposed to 7.65.........meaning the gap between rollers is 0.14mm smaller.

Currently I am using the same checker I have always used so I am assuming when it gets to 0.5% wear on the flat top chain using it, the wear is actually more than that.......but still well within 0.8%. ?

 

[RickBullotta]

The Pedro's branded tool is half the price but authorized by SRAM.

 

[steve_sordy]

@Mikerb Remove the chain, stretch out on a flat surface and with a metal tape, measure pin to pin over 100 links. A new chain will measure 50" exactly, one at 0.8% will measure 50.4". Because most metal tapes in the UK have 1/16" increments, the nearest fractional measure will be 13/32" (0.406"). That is easy to estimate. To get that level of accuracy, it will be easier if you have another person at the idiot end to help keep the chain taut and also to get one of the bold inch markers exactly over the centre of one of the pins. The usual reject wear level is at 0.75% which is exactly 50-3/8".

The benefit of measuring this way is that it evens out the unequal wear that seems to happen across the chain's length. I know how to use a vernier calliper gauge and I can measure over 5"-6" with mine. I have learned to measure in various places across the chain because I could not believe how much variation I was getting. I repeated the measurement and I was consistent each time. The chain wear was indeed a variable! (Others have reported this). Why this should be I have no idea, the various components are randomly mixed components each of which has been mass produced in the millions. That should result in zero variation.

Removing the chain and measuring with a tape is faster and more accurate than repeated measurements with a chain gauge or even a vernier calliper gauge. Especially if the chain is coming off anyway!

 

[RustyIron]

I have SRAM Transmission obviously including a flat top chain. So how are you guys checking chain wear??
I have read conflicting information and some that makes little sense to me!!

I went out and got the Pedro's chain checker when I got my tranny drivetrain. At 1,077 miles, my chain was barely showing 0.5%, but I slapped on a new chain anyway. My thoughts are that when the new chain gets to be around 0.75%, I'll put the first one back on and then just run everything into the ground.

 

[Mikerb]

I agree measuring the chain is the best guide but it means removing it and using another set of powerlinks to put it back..assuming it is going back on. A checker is so much quicker but I agree it needs to be done in several locations because chain wear is not even.
My issue...even with the Pedros checker is that if flat top chain rollers have a greater diameter, the same checker cannot be a ccurate on all 11/12 speed chains or even just all 12 speed chains. The Pedro claims it can be used for all 12 speed chains.

Seems to me trying to claim any checker is specific to SRAM Flat top chains is just a con to get you to buy another. By my reckoning using any checker for 0.5% wear on a flat top chain means the wear is actually 0.07mm greater........and I doubt most checkers are 100% accurate in the first place.
In conclusion i will continue using my original park tool checker and change chain at 0.5% "indicated" or maybe do a couple more rides once it gets to that point. @RustyIron has it right reckon.........keep the original chain as an emergency trailside spare and put it back on when the replacement is toast...then put it back on and run both chain and cassette into the ground.

 

[RustyIron]

even with the Pedros checker is that if flat top chain rollers have a greater diameter, the same checker cannot be accurate on all 11/12 speed chains or even just all 12 speed chains. The Pedro claims it can be used for all 12 speed chains.

Therein lies the cleverness of their checker. It might be difficult to explain and will require a little visualization, but I'll try.

Old-school chain checkers measure the distance in between two rollers--the left of one roller to the right side of another. If we were to calculate the numeric value for that distance, it's going to be some multiple of 1/2" (the pitch of the chain), minus the diameter of a roller (2x the radius). If someone can't visualize that, go ahead and stick your checker onto the chain. You'll see what I'm talking about.

The problem arises with the larger diameter of the rollers on a flattop chain. The checker will be thrown off by the different dimensions. The measurement IN BETWEEN two rollers will be less, and the checker will always show less than the actual wear.

Now let's talk about measuring the pitch of a new chain. It doesn't really matter where we measure from, as long as we choose the same spot on the links. We can choose the centerline of the leading pins, the centerline of the trailing pins, the leading edge of the outer plate, the trailing edge of the outer plate, or even the middle of the plate, if we could figure out an easy way to mark the exact center. As long as we choose the same spot on the links, our measurement will always be a multiple of 1/2".

Pedro's came up with a weird little contraption that measures the RIGHT SIDE of pins that are ten links apart. What's important is they're measuring on the SAME SIDE of the pins--not the distance in between the pins. On a new chain, the Pedro's measurement is going to be an exact multiple of 1/2". Compare this with the second paragraph of my post. The diameter of the rollers is not relevant. Because the Pedro's tool is measuring the same spot on the links and the diameter of the rollers is not relevant, it can be used on different style chains.

Check out the attached picture of Pedro's tool. When in use, the hook labeled "1" grabs the RIGHT SIDE of a roller. The hook labeled "3" jams in on the RIGHT SIDE of another roller. The hooks are ten links apart. On a new chain, the distance between ten links is 5". You might not be able to see it in the picture, but Hook 3 is stepped. The distance between Hook 1 and the first step is 0.5% (0.025") greater than 5", and the distance between Hook 1 and the second step is 0.75% (0.0375") greater than 5".

 

[Mikerb]

just bought a Park tool CC 4...does the same method as the Pedros...Pedros not readilly avaialble in the UK.