Oval chainrings; hard sprinting?

Back by popular demand, the general all-things Road forum!

Moderator: robbosmans

Post Reply
TheDarkInstall
Posts: 725
Joined: Sun Jan 26, 2014 3:44 am

by TheDarkInstall

Alright

Have any of the sprinters on here (60kmph / 1200w+) done any massive leg outs on oval chain rings?

Any difference to round? Does the radial oscillation cause the chain to fling itself off at random, or does this not affect anything?

by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



User avatar
DMF
Posts: 1062
Joined: Sat Dec 06, 2008 10:14 am
Location: Sweden

by DMF

I've been on Q-Rings for years and recently switched to Osymetrics... My biggest problem when sprinting out of low speed, while ignoring all technique, is the rear wheel skipping a couple of centimeters off the ground, the moment it lands the front wheel gets a lift, at this point the handlebars are usually pointed anywhere else than forwards due to me pulling on them, so the front end will go wherever the bars are pointing when the front wheel hits the ground, causing something very close to what motorcyclists call a "high sider". From behind probably looks a little something like wrestling an angry bull.

This is what I'd call putting everything your body has got and then some into the bike.

Have NEVER had a problem due to oval rings...

Technically speaking, I don't see how the individual chain links would see/feel any oscillating effects. And as for round vs q-rings your cadence speed thru the whole stroke has way more variation with round rings. So for speed oscillation round rings will "oscillate" with a greater frequency.

Pardon any and all faulty use of technical terms here, I'm a bike mechanic not a university graduate :)

Zigmeister
Posts: 938
Joined: Mon Jan 24, 2011 8:09 pm

by Zigmeister

Consider myself a sprinter. I've been using QRings for about 4yrs now.

I would say the 2 things I notice: 1) Make sure I'm in 1 higher gear and turning lower RPM before starting a sprint. Since I'm often in 11spd already, not much I can do about that one.

And 2) when you move forward/backwards, you are in essence changing the Index of the ring. Just like you can change the ring with Rotor to different holes, it determines what point the down stroke pressure/speed happens.

Thus, is you move up forward and your knees move ahead of the spindle (assume you use KOPS setup) you are actually changing the Index and it then hits the "Bottom" earlier.

Hence, why I put it in 1 higher gear if possible, because as you get out of the saddle, your knee/body position changes causing the speed of the pedal stroke to accelerate earlier through the bottom.

If that makes sense?

So it makes a slight difference, but not really much on speed/power/top-end etc..

TheDarkInstall
Posts: 725
Joined: Sun Jan 26, 2014 3:44 am

by TheDarkInstall

Good info, thanks.

So, neither of you have had any issue with really pushing hard, and the chain coming off?

Marin
Posts: 4035
Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

The lower part of the chain is not tensioned even under hard efforts, so all it sees is the cadence.

I'm running Q-Rings and Dovals and have never had a chain come off at high cadence or otherwise.

tmr5555
Posts: 356
Joined: Tue Jan 28, 2014 12:13 am

by tmr5555

Running Doval 53-36. Pos. 3.
Previously was on 53-39.
I feel like any speed above 60 kph comes with difficulty, maybe it's just the top end gearing disadvantage coming off a 53.
Hit 62.8 kph today :-P, Might be imagining it but spinning the Doval up is much more difficult.
Example, some times you know 53x11 will be harder to turn so you sacrifice potential speed for cadence by down shifting the rear.
It feels like if I down shift the Doval which is already lacking the top end speed, I'll loose even more speed.
Other than the puzzling sprint performance, I like 'em!
Never thrown off a chain either.

Edit: To Doval users: Which position (2 or 4) would improve out of saddle sprints?
How would such a change impact the rest of the ride?

refthimos
Posts: 411
Joined: Fri May 25, 2012 6:02 pm

by refthimos

I'm a Cat 2, ride Q-rings on all my bikes (other than the track bike), hit around 1400W for 5 sec in a sprint, regularly sprint at 70kph, have at least 65,000 km on Q-rings, and have never had the chain come off.

It's a non-issue.
EVO1 | 5.37kg
EVO3 (sold) | 6.51kg
EVO4 | build thread coming soon
S5 Disc
SystemSix (sold) | 8.01kg
P5 Disc | heavy but fast

dmoneysworks
Posts: 166
Joined: Tue Aug 07, 2012 6:35 am
Location: Parakai, New Zealand

by dmoneysworks

+1 non-issue.

Osymetric user of 18mnths. Zero issues to report. I run the version with shift ramp/pins on big ring and they just work.


by Weenie


Visit starbike.com Online Retailer for HighEnd cycling components
Great Prices ✓    Broad Selection ✓    Worldwide Delivery ✓

www.starbike.com



nfecyle
Posts: 100
Joined: Sun Apr 22, 2012 6:05 am

by nfecyle

I am running new aero doval at pos 5. It feels better for sprinting and getting off saddle.

Sent from my SM-N900T using Tapatalk

Post Reply