Rotor crank and Q-ring

[Bo6]

I am having some minor knee pain on longer (60 km) rides and plan to change my stock Q45 crank set to a Rotor to get shorter cranks and try a Q ring. Hope this helps the Knee problem and helps me smoothly spin at a higher rpm. I plan to try a 40 tooth chainring vs the 42 standard one as I anticipate the 150 cranks will make it a bit harder to climb hills.
Will a 40 tooth Q ring be similar gearing to a 40 tooth round ring? Is the 2 teeth drop enough to compensate for the shorter cranks (I do not want to lose too much top end)? Are 150 cranks too short?
I welcome thoughts and comments from those who have made this kind of change.

 

[sixty-six]

firstly I would try to determine exactly where your knee pain is coming from. It is possible to have issues if your feet are not positioned correctly on the pedals, if you use cleats this is far easier to adjust. I personally would not change more than one thing at a time to redress your knee pain. Going for shorter cranks and oval chainrings at the same time will take a lot of bio mechanical adjustments, yes short cranks on recumbents are they way to go, maybe if you believe the continued hype about oval rings, try them later, I have always been somewhat skeptical on their claims, as versions of similar oval/elliptical tech has be resurrected regularly since the late 1880's !

 

[Bo6]

firstly I would try to determine exactly where your knee pain is coming from. It is possible to have issues if your feet are not positioned correctly on the pedals, if you use cleats this is far easier to adjust. I personally would not change more than one thing at a time to redress your knee pain. Going for shorter cranks and oval chainrings at the same time will take a lot of bio mechanical adjustments, yes short cranks on recumbents are they way to go, maybe if you believe the continued hype about oval rings, try them later, I have always been somewhat skeptical on their claims, as versions of similar oval/elliptical tech has be resurrected regularly since the late 1880's !

Thanks, you are probably correct too many changes to access the results. May order Q and round rings. I do have SPD peddles and have worked with set up and boom length to get rid of most of the pain this is the next/last step.

 

[sixty-six]

Thanks, you are probably correct too many changes to access the results. May order Q and round rings. I do have SPD peddles and have worked with set up and boom length to get rid of most of the pain this is the next/last step.

I would go for short cranks but not bother with the q rings, also look at your cleat position, it is better to have them further back on shorter cranks, also having them too far in or out will aggravate knee problems. 155/160 cranks will greatly reduce the amount your knee raises which in turn could be aggravating you knee issues.
If there is a persistent pain or the discomfort comes on sooner into your rides, it is a very good idea to get an mri just to ensure there is nothing too serious...we expect some wear and tear after years of cycling, but constant discomfort is never a good sign.

 

[Bo6]

Mounted the155 Rotor cranks with a 42 tooth chain ring as per stock and put on a few hundred km. The knee pain did not go away totally but did decrease significantly. The shorter cranks did make the hills seem a bit steeper and I did end up gearing down and increasing the cadence on uphill sections.

Put on a 42 tooth direct mount Rotor Q ring and went out for a 35 km test ride to compare with the round ring. The instructions were a bit hard to understand so I mount the ring at the 2 position on the axle. The felt very natural and smooth, kind of felt like I was peddling in circles vs my usual "squares". I was able to get an even power with very little wobble upto ~100 RPM. I did have to use a one gear lower on the steeper hills. If anyone has more information on tuning the ring position, I would appreciate a link to more information or some advice on set up for recumbents.