late

These are oval chain rings that are supposed to be easy on knees. Look expensive.

I'm retired, so the idea of making life a little easier on my antique knees sounds great.

https://rotorbike.com/catalog/default/#

Bill Kapaun

Just a take on Shimano Bio Pace.
People tend to love or hate elliptical rings.

late

I put those on a bike, at some point. I honestly don't remember anything about them.

Bill Kapaun

I've had them years ago. I'm basically neutral about them.
My knees (and age) are a lot worse, so I use 165mm cranks and low gears.
My bikes would normally be of the 28-38-48 ilk and I've gone to 22-32-44.

Marcus_Ti

Non-round chainrings have been around for the safety bicycles since the safety-bicycle was patented. They've never really caught on in all that time in spite of a dozen major iterations at least each claiming to have "solved" the one thing stopping them from working.

Then again, like chiropractic, and acupuncture, and alkalinized water, and kinesio-tape .....there are believers out there who swear up and down.

dsaul

Shimano Bio Pace rings had the clocking of the oval wrong and were not effective. I'm not sure what clocking Rotor uses, but Absolute Black seem to have it right. I have one of their oval rings on my 1x mountain bike. For a cheaper option, USA Made https://usamadeco.com/collections has some oval rings that are relatively inexpensive. I have one of their 34t ovals as the small ring on my gravel bike. I don't like their clocking, but it was relatively easy to rotate the ring to clock it like the Absolute Black rings. They make a very noticeable difference in being able to maintain a higher cadence while climbing. The effect is less noticeable on the large chainring of my road bike and is probably not worth the expense.

AnkleWork

No bike designed for the tour de France (or anything like it) will be easy on the knees.

Jon T

After 20 years of riding eliptical rings the best thing I did was to go back to round rings. Just for the record I'm 64 yo so I know about bad knees. The round rings are easier on MY knees and better shifting. My rear cluster is 13-28 (6-speed) and the front is 26-42-50.
Jon

Crankycrank

Oval rings are one of those things you just have to try for yourself. A few people love them (I know a guy named Chris Froome who likes them) but most don't from what I've seen. I feel your pain trying to keep the old body turning so if it were me I would try them and if they don't work try selling them on EBAY or ?? to recoup your costs or better yet, try looking for some used ones and you may get lucky. As mentioned other than ROTOR, ABSOLUTE BLACK & USA MADE makes them and maybe some others.

djb

back in the Biopace days, in 1990 or 91, I bought a touring bike that came with them, and swore I would never ride them again after taking them off to replace with round rings after a season (that had some knee issues)

I'll never know if the knee problem was associated to the Biopace or simply overworking the knee riding too heavily loaded with inadequate gearing for the bike weight and hills....BUT I do know for certain that my knees immediately liked going back to round rings that didnt bounce my legs and knees around at higher cadences.
I guess it would be interesting to try some newer rings, and being a stronger cyclist now than back then, not riding a 7 speed dt shifting bike with regular pedals and straps that I used to tighten very tight so little "float".
I suspect I would keep tabs on cadences better--but who knows, I have no urge to spend the money to find out, but mostly due to my 28 year memories of having a buggered up knee during a cycle tour, having to take a few days off and cycling one legged to a doctors office to get some anti inflammatory pills.

as mentioned, clearly they work for people (Froome) and Im sure the technology and understanding of how they work are much better than before.

ps, its too bad that its not easier to be able to try some back to back vs round, as it really would need some proper riding to get used to them and adjusting your cadence a bit, to really know how you find them.

I guess all you can do is read up on reviews and accounts of riders who use them and their recommendations of possible pedalling stroke technique changes vs round.

WizardOfBoz

BTW, if you get the Rotor 1x13 groupset, its' only about $5000.

djb

or as we say up here in The Great White North, $6549.05
I betcha I could fly to and tour South America for 3 months on that stack of nickels, using my 44/32/22 equipped 9 speed donkey, and my getting up there knees would be happy.

yannisg

I have been using Rotor oval chainrings for many years on my training bike.
When I race (2 or 3 races) per year or on Brevets (200k to 1000k) I use round rings.
After all these years I still cannot pin point any advantages of the oval rings versus the round ones.
When I'll replace the oval rings, I most likely, will install round ones.

davidad

Biopace (Jobst Brandt) (yarchive.net)