Steel Chainrings - Rare?
 

Just wondering if steel chainrings are rare. It seems all I look for are aluminum.

The reason I ask is because I had replaced the chain on my Norco assuming the old chain was the reason for the tight spot I had in the chain adjustment. Turns out the front chain ring/crank is about 2mm laterally out of true.

While the chainring's teeth are okay, the way the chain wore the valleys between the teeth pushed metal out to one side of about half of the valleys. I cleaned it all up with a small file on the side of the valleys.

Then it got me thinking why not a more durable solution such as a steel chainring on a single chain ring bike? The single rear sprocket is steel, and of course the chain is steel. It made me think of the aluminum sprockets on motorcycles and how much I hated them on non-racing machines.

https://cimg5.ibsrv.net/gimg/bikefor...ac4b85f49d.jpg

Surly QBP, currently offers stainless steel chain rings ..

though 7075-T6 aluminum heat treated alloys are very long wearing ,
and are hard enough to require machining..

and weigh less , so that is common on higher end cranksets ...







....

If this is a single speed bike you ran your chain too tight.
7075 alloy is harder than a lot of steel. What's not to like?

You can find oodles of steel rings at X-Mart.

Another cause of your problem may have been a worn chain.
IF everything is in spec, the load is borne by a lot more teeth than if the chain is worn/elongated.

Internal gear hub, but yes a single speed chain set up.

Due to the out of true crank/chainring mount, the chain goes from loose to tight through its rotation. If I adjust the chain tension properly for the tight spot, then the loose section of sounds like the chain jumps teeth when under heavy load when starting from a stop.

Edit: Added "sounds like".

Yep, I thought the chain was worn unevenly too. The new chain I installed yesterday didn't make the tight to loose chain tension problem go away. That's when I noticed the crank/chainring being out of true laterally. :(

Excellent. Thanks! :thumb:

https://surlybikes.com/parts/stainless_steel_chainrings

Usually it's the rear hub that is out of true.

Something to check for, that's for sure. :)

I've read that alu chainrings wear not that much slower than steel.

First, if your chain is not that worn, chainrings will last a very long time, into the 10k+ mileage range. Pooched chains will rapidly wear out rings and rear cogs.

The expensive approach to bike maintenance is to let the chain wear out well past 2k miles, at which the rest of the drivetrain goes bad exponentially. The correct approach is to replace (with cheap) chains every 2k miles, and get 3-4 chains worth of wear out of the rest of the (expensive) parts of the drivetrain.

Second reason why steel rings may not last much longer, and I've not seen a scientific study on this, is silicates. Basically a major component of road grit/dirt. Hard minerals that get pressed by the chain bushings into the softer alu of the rings. So the wear surface of the rings is hardened by impacted silicates. Take this for what it's worth.

Nevertheless, I've ridden alu rings for 50 years, and I find it takes immense miles and/or abuse to wear out a ring.

Worn chains and cog skip under loads are completely different issues from the tight/loose cycles of chain tension in a non spring loaded tensioner system (single speed or fixed gears). Also ring lateral "trueness" has nearly nothing to do with chain tension. Lastly was the old ring an even tooth count one? If so then no wonder the teeth wear pattern is alternating, the chain has inner then outer plates which contact the teeth. An even toothed ring will have the inner plates only touch every other tooth. Had the ring been an odd tooth count I suspect the wear would have been more even (bad pun) Andy

42 tooth chain ring. The worn valleys are not alternating, but only on one half circle of the chain ring. Say, 22 teeth in a row all okay, 20 teeth in a row with bulged out valleys only on the right side of the chain ring as mounted on the bike.

The chain line isn't perfectly straight. The rear sprocket (20T) is offset to the right about one chain width compared to the chain ring.

Edit to add: The wear in the valleys between the chain ring teeth appears to be from the chain rollers. Sorry that I don't have a better photo.

I just wanted to thank you all for adding to the thread. :)

I went back to check the sprocket, chainring, and right crank using zip ties mounted to the bike and cut to length.

The rear sprocket appears to be good, but the offset dish of that sprocket makes the chain line a bit off. Could use a non-dished (flat) rear sprocket.

The chain ring doesn't seem to run "out of round", but it definitely has a lateral alignment problem which is caused by the right crank.

The way the crank is out of true laterally is as if some force hit the pedal on that side forcing the pedal inwards into the bike. Which made the crank follow. I don't know when this may have happened as I bought the bike used with no pedals.

While slowly cranking the pedals by hand, I can hear some of the chain's inner side links popping over the rear sprocket teeth. Not the chain rollers like I thought before, just the inner side links. To ease the chain's ability to make the imperfect chainline, I have the rear wheel aimed toward the chainring by about 1mm.

Still, the brand new chain I installed yesterday definitely has tight and loose spots, just like the old chain. I'll look into getting a flat rear sprocket to mount up to see if that helps the chain line issue.

One trick you can try to "correct" out of round rings is to install the ring but only snug the chain ring bolts a small amount. Then install the chain and set the tension (or really the lack of) and spin the system so that you find the tight chain spot. Stop the cranks at that point and grab the chain's upper and lower run in your hand and squeeze. This can sometimes shift the ring on the bolts to a more centered location. Then tighten the bolts. Also rotating the ring WRT the crank's spider arms can sometimes reduce the out of round.

Remember that zero chain tension is the correct amount. So the tightest spot should still have some slop. It sounds like your uneven tooth wear is from the tight spot being too tight. But rings do wear unevenly due to chain pulling on the rear cogs. Chain ring teeth that line up with the pedals at about 2:00 (viewed from the RH side) will see greater tension from pedaling forces. Andy

I like that chain squeeze technique of centering the chain ring. Hadn't thought of that. Thanks! :thumb:

Judicious tapping with a rubber or rawhide mallet works as well. Just make small adjustments until you get the best alignment.