-
• #27
I used Biopace on my geared bike for years and always seemed to get on with it. When my commute distance went up and was pan flat I switched to doing most of my miles with fixed gear. At that point, the Biopace started to feel a bit strange, sort of inefficient feeling in getting the power through to the wheels. I think it's because the gearing gets taller in the dead spots, which means the feet slow down somewhat. I wonder, in hindsight, if this sudden change in velocity at the top and bottom of the stroke was a contributing factor in my knee injury. I've currently got round rings on the geared bike and I have to say they go round more smoothly than the Biopace did.
Tldr; I haven't made my mind up yet about Biopace :D
-
• #28
My uncle's brother was a pro-cyclist in his day, and that was what he said "I tried those biopace, hurt like hell, you shouldn't use shit like that".
But Biopace got the chainrings in the opposite position, compared to today's non circular chainrings (Doval, Rotor, Osymetrics). They got it totally wrong, and that's why many people that tried them or heard about them don't even want to get near todays other options.
This is a biopace description image:
You can see how the radius was higher in the deadspot, and smaller in the point where you could deliver the most amount of power. The opposite to what Doval, Rotor, Osymetrics try to do...
About the knee problems, I'm my experience (road, mtb, fixie, etc...) People tend to use their bikes without a good initial position adjustment, or at least without re-adjusting when something starts hurting, and then blames the saddle, or whatever else... but I just did 1000km straight and nothing hurt, so it must have something to do with a good biomechanical study. But its also true that there is people that a small amount of change in the position creates a lot of problems for them, whereas others tend to just adapt and don't get hurt...
-
• #29
@bertocq Thank you for your input - I have been reading through the thread but it is still too technical for me! Not just the dual-ovality but also the "5 positions".
I ride 50/34 with an 11-28 cassette and spend most of my time in the UK on the 'big' ring and mid-cassette.
I had a look online and I found another (french) company selling dual-oval chainrings:
http://dual-oval.com/Prices are half way between Doval and Osymetric at £80 for a set.
Their tech info is limited and looks like a copy/paste mash of other brands:
~Dual-Oval trays are made of Aluminum CNC T6 treatment.
The concept and design are 100% French, they are formed at an oval twice as Osymétric (less pronounced anyway) and not as a simple oval rotor.
The roundness of the Dual-Oval trays is similar to Osymetric trays or new Rotor QXL. However, Dual Oval trays are different from their twin oval design which creates a longer support (77 °), each pedal stroke is more efficient.
The oval dual eliminates dead spots, compared to a simple oval is more progressive.
When the dead come, the plate diameter gradually reduced and after gradually increasing.
Dual-Oval trays allow to gain power, endurance and reduce joint stress on your joints.
-Pédalage Rounder.
-consumption Of lower O2.
Reduces joint stress the knee.
Reduces the production of lactic acid.
Reduces heart rate.
External shelves are adjustable in 3 positions micro OCP.
It is recommended to try all positions and make your own judgment about which way you want. However, generally the riders who tend to have a high rate use more position 3 while the runners who have lower rates tend to use the position 1.
~ -
• #30
What is the question? Can't understand if you are advertising the dual-oval or asking for a comparison
-
• #31
I ordered me a pair of dovals in 50 x 36 (both 13,5%). Will report how they feel in a few weeks :-)
-
• #32
Reydels were pretty wild. Equivalent gearing change is from 48 teeth at the low spot to 60 teeth at the top. I can't wait to destroy my new knee on them!
1 Attachment
-
• #33
I would like to know if there is a difference between Doval & Dual Oval.
I copied / pasted the Dual-Oval information for you to add to your initial post.
If I normally ride 50x34, should I also buy 50x34 in non circular?
-
• #34
I've added them! It's true they weren't on the list, but I knew about them from @CarlosBI. Seems like a complicated copy of Doval, with two separate optional adjusters... need to get a decent internet connection to see their french videos to understand how they work.
No clue about the circular to non-circular relation, just wrote about my experience some post earlier... went from 50x34 circular to 52x36 Doval and everything was still the same in terms of climbing and fast flats, but it just could be me getting stronger.
-
• #35
I have just bought some Doval to try out.
Less than £36 posted for the set, which almost sounds too cheap...Went for 50T(13.5%)/34T(12.1%) and will report back.
They are working on a carbon version which will be released later on this year.
-
• #36
just noticed that there is significant difference between 11 + 16 vs 13.5 chainrings regarding the dead spot location. How do expert feel on this? I ordered the 13 just to be on the "safe side" of being in the middle of the curve, and now I fear I chose the wrong type :D
-
• #37
I have an Absolute black chainring for my AM bike. Which I'll be finishing soon (promise).
I have worn out my Doval rings. They didnt last long. But if you take into account cost they were still amazing value. I actually quite like them.
Going to replace them With Absolute Black road rings I think.
-
• #38
First ride on Doval chainrings this morning. I rather like them. Initially found it to be a strange sensation, but once I got going it felt pretty natural. Out of the saddle feels a bit like riding fixed and I noticed that I was pushing a bigger gear without really feeling too knackered. This is on a rebuilt bike with brand new frame and I think the saddle was a little high so I'll tinker about with that and report back.
-
• #39
ye ive done couple of rides on mine now
while cruising with low effort they feel weird, once you get some speed they feel weirdly natural
climbing out of saddle feels a lot softer
somehow my calves are doing more work which is good
-
• #40
but overall the experience was so positive I already ordered Rotor qcx1 oval nw ring for my cross bike
-
• #41
Had a few commutes on these now. No problems on the long ride home last night and my housemate joined me for a long (and fast) commute this morning, again fine.
This afternoon I got on the bike and immediately felt slow. My legs felt knackered. No joint pain or anything, but my legs just felt dead and I stopped at one point to drop my saddle a touch, as it felt like my legs were over-extending (hard to explain). Tried to keep my cadence relatively high and kinda bimbled home.
Anyway, that's my latest update, is this something anyone else has experienced?
-
• #42
Doval update. Two 8th places on two strava segments in SE London in two days. Not super-busy segments, not a scientific test, but I like these rings. Those are my first top tens in ages :)
-
• #43
Doval have released a new Doval Clipless model. Looks to be a different shape, 10.8% ovality. Guess I'll try them when these ones wear out.
-
• #44
Having said I wouldn't order another set, I've ordered another set. Big ring is just too good, will put up with the weird low cadence feeling of the small ring. They've unfortunately gone from all black to ugly white lines and writing all over. Including this top tip:
1 Attachment
-
• #45
Is that the new shape doval for clipless ones? Looks like the ovality is less pronounced than the ones I bought. Interested to hear how you get on with them.
-
• #46
Don't know if it's new shape. It's this http://www.ebay.co.uk/itm/2016-New-DOVAL-Chainring-set-BCD110-MGLR-ALL-in-one-11-7-13-5-16-Black-/121858153716?roken=cUgayN
Laid it over my old one (2 years old) and pretty much identical shape.
-
• #47
Got a new set of Doval chainrings - "ultra low ovality for clipless", so 4% 52t and 6% 36t.
Obviously less egg-shaped than the previous 16% set, but also a different shape. They reckon they've finally taken into account how clipless pedals affect the pedal stroke.
Messaged them on eBay (doval_su) and got this reply:
"Ultra low Ovality(5% below) chainring have just been developed.
It took us a long time to make ultra low ovality chainrings.
I am sorry to have made the chainring late."They feel good, done about 60 miles on them thus far.
-
• #48
But you had experienced the 16% ones right? Do you feel much difference?
-
• #49
Yeah, I did about 2500ish miles with the 16% rings. I've mostly been riding the Brompton lately, with round ring. Going from that to 16% oval there's a really noticeable feeling of the foot 'sliding' over the top of the pedal stroke. Also this effect is noticeable when climbing seated.
Going from Brompton to 4% oval the difference is much less apparent. I'll need to do more miles on them I think (but thus far I've been very lazy over xmas). There's still a hint of that sliding sensation and generally I think the 4% made the same gearing feel higher/harder than previously with the 16%.
-
• #50
I thought about using Doval as well on my Brompton, but I've stopped riding for some months, maybe on spring I'll retake interest. Are you planning to do so on your Brompton?
Anyway why I can't understand is why going for just 4%? Benefit in my opinion is just getting your legs a little less tired by avoiding that effort when pedals are at 12:30 position, I tried max % to see how it felt and was only thinking about decreasing it in case it was so radical I would get uncomfortable/injured.
I recall pedalling smoother while climbing out of the saddle with Doval compared to circular rings from my last rides, but can't truly compare if it was just my legs getting fitter.
Well the screw has a flat head (the part in contact with the ring) so any screw with the correct length and size will do.
I played a bit with it, to change from positions 1 to 5, but ended in the middle position from about km 600 and never looked back. Maybe I'll try to play again with it this autumn