So … the Doval odd shaped chainring.  How does it compare to the Osymetric one which comes in at 3 or 4 times the price?


                                                                             To be quite honest with you, the testing protocol wasn’t very scientific … in fact it wasn’t scientific at all … period!


                                                                              I do lots of miles in training. Most of them are done on measured 10, 25 and 50 mile routes and I ride them VERY

                                                                              frequently.  Other than my work commuting miles, that’s been the basis of my training since I started racing over

                                                                              40 years ago.


                                                                              Having recently packed in work, I’m doing more of that sort of riding than ever before and because I’ve done the

                                                                              routes so often I have a pretty good idea if anything is going to make any difference to how fast I go.


                                                                              When I first tried the Osymetrics (see
Nob’s test results too) I did feel a difference, but it wasn’t a very pleasant

                                                                              one!  I left home on the small ring to ride up to the A428 to ride a ‘25’ and was immediately struck by how jerky

                                                                              the pedalling action was (that’s jerky as in twitchy and not smooth … not jerky as in ‘Spiedi from Celebrity Big

                                                                              Brother’ or Beef jerky as in ‘lean meat that has been trimmed of fat, cut into strips, and then dried to prevent

                                                                              spoilage’).  ;-)


                                                                              The Osymetrics suddenly didn’t seem to be such a good idea!


                                                                              I pressed on though and once I got in to the actual ride (using the 56 ring) it did feel a lot better and, overall, I was

                                                                              impressed with the results.


However, there’s no disputing the fact that they are expensive and I’ve got a habit of wearing out kit (I don’t like spending money … I’m tight … well aren’t all testers?) so I couldn’t resist the 56 teeth Doval that came up on eBay for a little under £40.  It arrived within 10 days or so and was fitted to an old time trial bike of mine ready to be tested on the next dry day (not only am I tight … I don’t like cleaning bikes either). 


A couple of weeks later it eventually dried up … just in time to snow … but there was a window of opportunity I wasn’t going to miss so I was up and out on the A428 again.  Although there was a similar ‘jerkiness’ to the low gear pedalling it wasn’t quite as noticeable as with the Osymetrics. I suspect this was mainly due to the ‘squarer’ shape of them (as opposed to the extreme ovalisation of the Osymetrics).  I also noticed that the positioning of the ring on the cranks was slightly different too! 


Rotor have patented a feature which is apparently the secret to success  … the Holly Grail being the OCP (Optimum Chainring Position)!  A number of different fitting holes on their chainring allows you to ‘choose the angle where you can obtain the maximum gear ratio, customizing pedalling to each and every cyclist’ … the blurb goes on (just Google Rotor Q ring for more)!   Nob did make reference to all that in his report but it was far too technical for me to fully understand. 


To cut a long story short, the Rotor OCP allows you to fit the chainring at a number of different angles to the crank.  You can’t do that with the Osymetrics although you could, of course, rotate the ring by 1/5, 2/5 etc and see what sort of difference that makes but I suspect that’s not really a very good idea and certainly isn’t recommended by the manufacturers (so I’m naturally going to give it a try as soon as the snow’s cleared up).  


So … when the widest point of the Osymetric is in the vertical plain, you’ll find that the cranks will be horizontal.  With the Dovals, I found the cranks to be in a more of a 4 o'clock position which tied in pretty well with the argument Rotor are putting forward with their Q rings. Co-incidentally, Doval also utilise an Optimum Chainring Position facility although the range is minimal compared to the Rotor's and they don't appear to have 'patented' either the design or the use of the acronym OCP presumably not considering the patent to be worth the paper it's printed on! 


Who’s right and who's wrong ... and are they any faster than round rings?  God only knows (so much for the tests eh?) but I'm pretty sure the shape of the rings will have some effect on how you ride … you only have to lift the back end of the bike off the ground and spin the cranks to see (and feel) that ‘something’ is definitely going on. 

P bus

I DID go faster than I've ever gone before (at this time of year) during my test ride so I suppose I'm a convert as far as the shape of the rings are concerned but it would take someone more gifted in the IQ department than I am to say whether or not there’s anything in the OCP business.


Doval gets my vote … definitely worth a punt at £40 or so.