Osymetric chain rings

S

Sonnybea

Active Member
Has anybody out there used Osymetric chain rings
I installed a set but they are having issues. My pedal stroke bounces at 90+ rpm and I can't hold a straight line
Any thoughts
 
Don1

Don1

Guru
I suspect that it isn't aligned correctly for recumbent use. I have some and are about to get the welder out to make new mount tabs.....
 
S

Sonnybea

Active Member
When you align the rings are you going by chain line or power stroke with legs
I tried the chain line and they bounced way to much
So I set them up like I did my c.a. 2.0 much better
Getting ready to try them out this morning
 
chicorider

chicorider

Zen MBB Master
I have a set of these one the way. I'll be interested to hear how they are working for you, and will chime in when I have some mileage on mine.
 
billyk

billyk

Guru
There's been much discussion of oval rings on this forum. Right, per @Don1 above, the positioning is different than it would be on an upright.

Try searching for posts some years back by John Tolhurst (legendary inventor of the cruzbike) on how to find the correct position.
 
S

Sonnybea

Active Member
I tried the bike yesterday, on my senior citizen ride we maintain 20mph for 30 miles.
Well I stayed in my 34 ring the whole ride with no problems, and one short sprint I hit 26mph in my 34/11
Osymetric rings are a love/hate relationship plus they really don't support recumbents .
 
B

Bill Barrere

New Member
This is a Twin Cam ring we designed to be adjustable for the proper chainline orientation on all bents and trikes.
1673969027971.png
A cam lobe on a turning shaft increases the diameter, as in an engine. A Twin Cam chainring increases the size of the gear when you push the hardest (outward strokes) and pull through the inward strokes, then it decreases the size of the gear to get through the dead zones quickly with power. This places the force on the pedals to be constantly proportional to the muscular force of the rider. The varying diameter alters the effective gear ratio throughout the pedal stroke by 4 teeth, creating less time in the dead zone. One would think this variation would make the stroke erratic, but just the opposite is true, as one has almost continuous power on the pedal stroke. The pedal stroke is perfectly smooth.

When a round ring is placed next to a T/C ring and shifted back and forth, when in the round ring one's legs will speed up and slow down due to the dead zone.
Steve J posted this reply about 5 years ago. "Bill wasn't done with me yet, He talked to me about Twin Cam Rings. I told him they sounded great but I was already in love with my Q-Rings. He wouldn't hear that and sent me a ring to try side by side with my Q-Ring. I put both rings on so I could shift from one to the other. I had no intentions of taking off my perfectly good Q-Rings and buying different ones! But again to me, there was a big difference and I was sold and switched to the Twin Cam's. Personally, everything has worked out wonderfully.

From comments and replies on this FB post, https://www.facebook.com/groups/226407825133603/posts/834727880968258/ The T/C ring orientation to the chainline is simple. The red dots need to face outward on each ring. The right side pedal should be at full length of the rider's pedal stroke. The chain needs to be in a straight line from the flat on the top of the rings to the idler, or cassette on some LWB bents.

A power meter won't show an increase in the pedal stroke. The T/C ring performance increase comes from maintaining power in the 4 dead zones, each about 30 degrees on each pedal stroke.

We now have finished the CAD files for the 4 most used cranksets, 130 BCD mm 5 bolt, 110 mm 5 & 4 bolt, 74 mm 5 bolt and 104 4 bolt. The sizes range from 60 tooth to 26 tooth along with bashguards. Bill, RECUMBENT ONE
This is a Twin Cam ring we designed to be adjustable for the proper chainline orientation on all bents and trikes.

A cam lobe on a turning shaft increases the diameter, as in an engine. A Twin Cam chainring increases the size of the gear when you push the hardest (outward strokes) and pull through the inward strokes, then it decreases the size of the gear to get through the dead zones quickly with power. This places the force on the pedals to be constantly proportional to the muscular force of the rider. The varying diameter alters the effective gear ratio throughout the pedal stroke by 4 teeth, creating less time in the dead zone. One would think this variation would make the stroke erratic, but just the opposite is true, as one has almost continuous power on the pedal stroke. The pedal stroke is perfectly smooth.

When a round ring is placed next to a T/C ring and shifted back and forth, when in the round ring one's legs will speed up and slow down due to the dead zone.
Steve J posted this reply about 5 years ago. "Bill wasn't done with me yet, He talked to me about Twin Cam Rings. I told him they sounded great but I was already in love with my Q-Rings. He wouldn't hear that and sent me a ring to try side by side with my Q-Ring. I put both rings on so I could shift from one to the other. I had no intentions of taking off my perfectly good Q-Rings and buying different ones! But again to me, there was a big difference and I was sold and switched to the Twin Cam's. Personally, everything has worked out wonderfully.

From comments and replies on this FB post, https://www.facebook.com/groups/226407825133603/posts/834727880968258/ The T/C ring orientation to the chainline is simple. The red dots need to face outward on each ring. The right side pedal should be at full length of the rider's pedal stroke. The chain needs to be in a straight line from the flat on the top of the rings to the idler, or cassette on some LWB bents.

A power meter won't show an increase in the pedal stroke. The T/C ring performance increase comes from maintaining power in the 4 dead zones, each about 30 degrees on each pedal stroke.

We now have finished the CAD files for the 4 most used cranksets, 130 BCD mm 5 bolt, 110 mm 5 & 4 bolt, 74 mm 5 bolt and 104 4 bolt. The sizes range from 60 tooth to 26 tooth along with bashguards. Bill, RECUMBENT ONE
 
V

vosadrian

Guru
Bill Barrere said:
When a round ring is placed next to a T/C ring and shifted back and forth, when in the round ring one's legs will speed up and slow down due to the dead zone.
Click to expand...

Is that really true? With a round ring the gear ratio is constant at all times. If you are going fast enough that your bikes speed is constant (say a bent travelling on flat roads at 20mph), and you are keeping some pressure on the pedals at all times to prevent the ratchet from disengaging, then that would imply that if the wheels travel at constant speed, then with constant gear ratio, the pedals will also travel at constant speed. In contrast, the varying ratio of the non-circular ring will cause the pedal speed to change if the wheels stay at the same speed.

Of course if you are going very slowly up a hill, then the bike can accelerate/decelerate every pedals stroke, so this may not apply. But for most bent riding at speed, the bike does not change speed much (if at all) with every pedal stroke.

My point is that the dead zones will not effect leg speed.... the speed is set by the bike speed once you have momentum.
 
David Lalejini

David Lalejini

Member
vosadrian said:
Is that really true? With a round ring the gear ratio is constant at all times. If you are going fast enough that your bikes speed is constant (say a bent travelling on flat roads at 20mph), and you are keeping some pressure on the pedals at all times to prevent the ratchet from disengaging, then that would imply that if the wheels travel at constant speed, then with constant gear ratio, the pedals will also travel at constant speed. In contrast, the varying ratio of the non-circular ring will cause the pedal speed to change if the wheels stay at the same speed.

Of course if you are going very slowly up a hill, then the bike can accelerate/decelerate every pedals stroke, so this may not apply. But for most bent riding at speed, the bike does not change speed much (if at all) with every pedal stroke.

My point is that the dead zones will not effect leg speed.... the speed is set by the bike speed once you have momentum.
Click to expand...
Certainly the bike speed won’t fluctuate, but the mechanical advantage of your legs through the pedal stroke must mean something? The twin cam design changes the mechanical advantage, so when you are pedaling through the dead zone (your weakest point of your pedal stroke), it is easier to pedal (but your feet will have to go faster). Maybe for some they don’t like it, but I have gotten used to them and it feels awkward to go back to round rings. Timing is critical, and Bill’s rings have a lot more adjustment than any other oval ring, great for recumbents. I have Bill’s twin cam on a trike, and Osymetric on my Vendetta. I can get the Osymetrics close but not like Bill’s.
 
V

vosadrian

Guru
I'm not saying they are not of benefit, I was just saying the quote above saying with round rings your legs speed up and slow down is not true. I think it is the other way around. With oval rings your legs speed up and slow down. I guess the idea is that you slow them down in high efficiency parts of the pedal stroke and speed it up in lower efficiency parts, so that you spend more times with your legs in the area they work well. I can't comment on whether it is beneficial of not. I'm happy with round rings and can't be bothered with another variable that I would not know if I had setup correctly. But I think some people swear by them.
 
B

Bill Barrere

New Member
vosadrian said:
I'm not saying they are not of benefit, I was just saying the quote above saying with round rings your legs speed up and slow down is not true. I think it is the other way around. With oval rings your legs speed up and slow down. I guess the idea is that you slow them down in high efficiency parts of the pedal stroke and speed it up in lower efficiency parts, so that you spend more times with your legs in the area they work well. I can't comment on whether it is beneficial of not. I'm happy with round rings and can't be bothered with another variable that I would not know if I had setup correctly. But I think some people swear by them.
Click to expand...
Hi V, I posted a reply to your comments. It seems to have gotten lost. I'd appreciate it if you could post it, had a couple of riders interested. Thanks
 
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