TheCharm 

Good day wrenches:

I have a 2015 Disc Trucker with the factory crankset. The big ring is starting to look worn. I don't a picture to attach, as I'm certain it's pretty close to needing replacement. And even if I can make it last the rest of this summer, I'd like to have something on hand, although I plan on swapping as soon as I can get a replacement. I've been taking some time during these covid restrictions to become more self-sufficient with my bike and I think I can handle this.

The bike shipped with an Andel RSC6 26/36/48 crankset. I don't think this is the exact model, as the model# doesn't match exactly, but this is a pretty good representation that Andel sells today, for a pictorial reference: ANDEL ENTERPRISE CO.,LTD.

I do not believe I will need a whole new crankset as the other chain rings are OK. I believe the spider setup on this crankset gives me the option to swap the big ring. I plan on keeping the same number of teeth, as I don't need to change any gear ratios. Looking around Andel's website, I can't seem to find an SKU I could procure and swap. So my first question is what do I need to know to find a suitable replacement? Obviously the number of teeth which I know, but are there differing spider bolt patterns if that question makes any sense? What facts/specs do I need to know to find a replacement?

Secondly, what tools and knowledge do I need to complete this job? It looks like an allen wrench will remove the fasteners but when I remove those, does the crank arm come off? How tight are those fasteners likely to be? I've never removed them, and I hope they aren't seized. Is there a recommended torque setting when I re-install? If anyone has any words of advice and wisdom (or links to YouTubes or other write-ups) to pass on I would certainly appreciate it. Also, if any other information is required to help you help me, please let me know.

Thanks much!

Andrew R Stewart 

No image was able to be seen via link so this is all blind thoughts- Are the rings able to be removed independent of the RH arm? (Or are there rivets that only look like bolts? What is the number of and center to center s[acing of the bolts? Does the large ring have shifting aids like lift pins or ramps? How many rear cogs does the bike have?

All the above is needed to be known before one can confirm or eliminate the possible replacements WRT fit and same spec.

For the outer/large ring (assuming it is bolted in place and not rivetted) one can generally just loosen the bolts and pull off that ring, leaving the nuts and middle ring in place. If the new ring is the same spec then no other work is needed after reinstall. If the ring has some different spec then possible ft der adjusting and/or indexing coordination adjustment (cable) can be needed too. The arm should not come off if just the ring bolts are played with although this is the right time to check the BB and arm retention bolts (usually either an 8mm hex socket or a 14mm bolt) conditions and secureness. Andy

cyccommute 

Let’s start with why you think the chainrings need replacing. Yours are relatively new. I’ve got chainrings with about 25,000 miles on them with loads more miles before they need replacement. Chain rings wear but they wear slowly.

If you are looking at your chainring and seeing teeth that don’t look like others, that is by design. Modern chainrings are asymmetric with different teeth profiles in different locations that aid in shifting. Often people see a flatter tooth and freak out. But that is a feature, not a flaw. A picture would be helpful in assessing whether they need replacement or not.

Your crank likely has a 110mm bolt circle diameter (BCD). Measuring it would be better than guessing but I can’t reach through the screen. Here’s a link to what ring to use based on the measurement. There is a link in that article on how to measure the BCD.

It’s relatively simple to replace the chainring (if you really need to replace it). Just unscrew the bolts and swap the ring. You may not even need to take the crankset off to do so. You can usually work the old ring off over the pedals or just remove the pedal before hand. If you are lucky, the chainring bolts will use 5mm Allen wrenches on the front and rear. If not you’ll need one of these. The chainring nut wrench is in hot contention for being the worst bicycle tool ever!

Don’t worry too much about torque, just get them tight. You might also take this opportunity to replace the chainring bolts with ones that use 5mm Allen wrenches on both sides. There are lots of aftermarket chainring bolts out there. You can even have fun with colors if you like.

Iride01 

I'd never expect a 6 year old bike to have worn rings unless I knew that you rode 5000 to 8,000 miles a year.

For certain if your rings are worn out then you also need to replace the chain. When is the last time you changed it? Not replacing chains does wear out rings and cassettes quickly.

I think the original crankset will be hard to source here in the USA even without COVID. You might be better off just replacing the entire crankset and BB. Especially if the rings for that are some oddball BCD.

TheCharm 

Sorry about that - I pasted in a link to the manufacture's site, not an image.

But to your other points, these are definitely bolts, not rivets that look like bolts. It appears to my inexperienced eyes that if I remove them, the big ring will come off. I will certainly take measurements, but based on some other comments, I *may* be a bit premature in my conclusion that it needs replacing. I will get some photos - I really should have done that in the first place.

Thank you very much for your input - this is a great place to learn.

TheCharm 

Thank you so much!! Excellent information. It does appear I should have taken some pictures which I will do and post back so everyone has some visual reference. Point taken about some teeth not looking like the others. The teeth on the big ring do look different than the other two and that was the basis for my conclusion, but again, pics will be added shortly. I do log between 5,000 and 6,000 miles a year on my bike, so likely at least 25,000 on the factory chainrings. I swap chains almost obsessively, as I learned fairly early on in my bike ownership that using chains for too many miles can cause premature wear on chainrings and cassette cogs. I install a new chain at the first sign of wear on my wear gauge.

TheCharm 

I do log between 5,000 and 6,000 per year. I will add some pictures very shortly - thanks much for your input.

TheCharm 

Please see the photos I've posted up. Thanks again for the help!

Iride01 

I'm impressed then. Sadly I just barely make 5,000 per year and the last couple years were embarrassingly less.

I'll assume that you have been replacing chains regularly then.

TheCharm 

I replace chains almost obsessively - I did learn fairly early on that trying to get too many miles out of a chain can cause premature wear on both chainrings and cassette cogs. I swap just as soon as I see the smallest bit of wear on my wear gauge.

HillRider

Everything you need to know is engraved on the chainring and fairly obvious from the photos:

1. This large chainring is a 48T, 110mm bolt circle diameter (BCD), 5-bolt chainring and replacements should be trivially easy to find. Shimano and others sell them.
2. The middle chainring is also a 110mm BCD 5-bolt chainring and uses the same bolts as the outer chainring.
3. The granny chainring has a separate 74mm BCD 5-bolt pattern which is also a common configuration.
4. Your chainring is by no means worn out. Those shaped teeth are done intentionally and, along with the pins, are there to improve shifting accuracy.

As mentioned by cyccomutte above, I also have a several cranks with well over 25,000 miles each and they are in fine condition, shifting well and running quietly.

TheCharm 

I really appreciate all the good feedback here - saved me a few bucks and now I'm all set for the summer riding season!

cpach

That looks fine. Chainrings are worn when:
-The chain skips or
-They shift poorly.

If neither is true, leave well enough alone.