Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars.

Mar 13, 21 18:53

Post #1 of 71 (2120 views)

Yes, clickbait title. Now help me! Thanks in advance.

TLDR: I sprint, chain pops off sometimes, this time I went over handlebars. I don't want to again.

Click here for me all scraped up:
https://www.strava.com/activities/4931974697

Is the frame flexibility the issue or is it the chainrings? Something else?

My bike:
Cannondale SuperSix Evo HiMod, Hollowtech cranks, Vision chainrings (unsure on model... but they look thin). I think this is the ring

I am hopeful someone can say with some confidence that it's the chainrings or some other component and not the bike because I don't want to buy a new bike!

Relevant info:

Chain is nearly new.
Cassette is nearly new.
Chainrings are 2 yrs old.
Chain pop-off happens to either side. Inside of small or outside of big.
Chain pop-off happens under high force situations (>1500 & <100rpm)
No other shifting issues, ever.

Any thoughts appreciated!

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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Last edited by: DrAlexHarrison: Mar 13, 21 18:53

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [DrAlexHarrison] [ In reply to ]

Mar 13, 21 18:56

Post #2 of 71 (2109 views)

Classic sign of worn out chainrings.

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [jaretj] [ In reply to ]

Mar 13, 21 18:58

Post #3 of 71 (2105 views)

jaretj wrote:

Classic sign of worn out chainrings.

Agree. Or an improperly installed quick link.

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Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [DrAlexHarrison] [ In reply to ]

Mar 13, 21 21:07

Post #4 of 71 (2014 views)

Gonna go with a worn out chainring here. I believe the carbon rings only last 5000 miles or so. Beingbthat youre a powerful dude, prob just wore it out. If the chain is new then it mustve slipped off the ring, i doubt the bike is the problem

If you want to do 2000w use a metal bike, carbon isnt great for shear torquing efforts... for drivetrain stuff that is

Last edited by: RossJ: Mar 13, 21 21:41

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [RossJ] [ In reply to ]

Mar 13, 21 21:12

Post #5 of 71 (2004 views)

Doubt it was the frame. Sean Kelly, one of the best road sprinters of his era, raced on a Vitus 979 for years, and that thing was an absolute noodle compared to anything that cannondale has ever produced.

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Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [RossJ] [ In reply to ]

Mar 13, 21 21:48

Post #6 of 71 (1975 views)

RossJ wrote:

Gonna go with a worn out chainring here. I believe the carbon rings only last 5000 miles or so. Beingbthat youre a powerful dude, prob just wore it out. If the chain is new then it mustve slipped off the ring, i doubt the bike is the problem

If you want to do 2000w use a metal bike, carbon isnt great for shear torquing efforts... for drivetrain stuff that is

Oh man - I'm SURE my 10-year old chainring on my Cervelo P2c is probably toast - I've never even thought about changing it! I've been going about everything else - new chains, new cassettes, new shifters and derailleurs, but I'm still using the original crank+chainrings from when I bought my bike.

I'm almost certainly going to have to chain mine - is this something that you just swap out the chainring and leave the crank, or do you have to buy the whole new front crankset?

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [JasoninHalifax] [ In reply to ]

Mar 13, 21 21:48

Post #7 of 71 (1975 views)

JasoninHalifax wrote:

Doubt it was the frame. Sean Kelly, one of the best road sprinters of his era, raced on a Vitus 979 for years, and that thing was an absolute noodle compared to anything that cannondale has ever produced.

I have a caad5 I have as my primary trainer bike and was my old road bike. I topped out about 1450w for sprints (nowhere near that now) and that did flex all over the place. The front mech used to catch the rings on occasion. The stronger I got the slower I became as the rear rim spent more time pushed against the brake pad. ;-)

Local bike shop owner gave it a test ride after it had been in for some work and after that spent ages checking the frame to find which weld had snapped as he couldn't believe everything was connected given the movement going on.

However, back to the OP. My non hi-mod Synapse is the most solid bike I've ridden, and so I cannot imagine the issue is with your frame, or even cranks/chainset.

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [RossJ] [ In reply to ]

Mar 13, 21 22:09

Post #8 of 71 (1959 views)

RossJ wrote:

I believe the carbon rings only last 5000 miles or so...

If you want to do 2000w use a metal bike, carbon isnt great for shear torquing efforts... for drivetrain stuff that is

They are alu chainrings, FWIW.

lightheir wrote:

I'm almost certainly going to have to chain mine - is this something that you just swap out the chainring and leave the crank, or do you have to buy the whole new front crankset?

I think there are a few one-offs with rings that are basically onepiece, but yeah, vast majority you can just buy the rings and replace. 15 minute job with the right tools. For bonus points, check your BB bearings while you're at it. I did my roadie's rings last weekend; super easy.

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Last edited by: justinhorne: Mar 13, 21 22:12

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [DrAlexHarrison] [ In reply to ]

Mar 13, 21 23:04

Post #9 of 71 (1925 views)

That almost happened to me. Terrifying. Turned out it was a worn out chain even though it was only 6 months old. Anyway, you should try different chainrings. Flat plate will never be as stiff as the wider Dura-Ace chainrings.

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [DrAlexHarrison] [ In reply to ]

Mar 14, 21 5:18

Post #10 of 71 (1842 views)

Talk to Nacer Bouhanni 2016 about apparently crappy (FSA) chainrings...
https://www.cyclingnews.com/news/bouhanni-i-felt-i-was-going-to-win-milan-san-remo/

Louis :-)

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [jaretj] [ In reply to ]

Mar 14, 21 9:21

Post #11 of 71 (1744 views)

jaretj wrote:

Classic sign of worn out chainrings.

Is there a way to visually inspect to confirm this? Telltale visual signs? Seems plausible, but I'm a little skittish to just throw on some stiffer/newer chainrings and go test sprints.

If it popped off at 1000W I'd more prone to try, but putting out 1500-2000W and having the chain come off is a pretty non-negligible chance of injury.

Thanks for your time!

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [Renault78law] [ In reply to ]

Mar 14, 21 9:22

Post #12 of 71 (1740 views)

Strongly considering. Just a little skittish to play test-dummy since it's only happening at near all-out exertion!

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [DrAlexHarrison] [ In reply to ]

Mar 14, 21 9:59

Post #13 of 71 (1698 views)

On a side note, we very rarely see pro roadies, or trackies falling when fails happen. The chain breaks, or drops, that's about it.
Good technique and balance is the key here.
If you go over the bars from a chain drop, something's done wrong IMO. Might put lots of watts on the little gadget on the crank (even more if you're a heavy rider), but not very efficient, might want to correct this also.

Louis :-)

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [louisn] [ In reply to ]

Mar 14, 21 10:04

Post #14 of 71 (1690 views)

louisn wrote:

On a side note, we very rarely see pro roadies, or trackies falling when fails happen. The chain breaks, or drops, that's about it.
Good technique and balance is the key here.
If you go over the bars from a chain drop, something's done wrong IMO. Might put lots of watts on the little gadget on the crank (even more if you're a heavy rider), but not very efficient, might want to correct this also.

Louis :-)

Yes, that has been my experience 9 times out of 10 too. Thankfully. It happened so fast this time that I'm unsure what exactly happened. I THINK that when the chain jumped off this time, because I was using the little ring (for fear of chain jumping off the big ring), I got chain suck which immediately froze my cranks in place and I think launched me up over the bars.

When the chain drops off the big ring during a sprint or snaps, the pedals continue to freely spin. I think that's probably the difference this time.

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [DrAlexHarrison] [ In reply to ]

Mar 14, 21 10:13

Post #15 of 71 (1678 views)

Oh! small ring ?
Happened on a good incline I suspect ? That's another story !
The small ring is usually straighforward in terms of machining, without any ramps or pins.
So yes, ring wear doubled with chain angle ( you must have been on little cogs at the back) might end up with a chain drop for sure when force is applied, add to that the chain tension must have been pretty low on "small-small", maybe just a bump on the road...

Louis :-)

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [louisn] [ In reply to ]

Mar 14, 21 10:18

Post #16 of 71 (1674 views)

Yeah 6% grade. Mt. Lemmon. Just finishing a fun ride with some sprints on tired legs. But the chain pops off on this bike at high watts whether using small or large ring. I just have never used the small ring or gone over the bars until a few days ago. I think I was in small ring and maybe 6-7th cog.

Chose the small ring because I was leery of chain popping off if using the big ring which happened earlier in the day at closer 35mph going downhill. No crash then, obviously. Figured surely the chain wouldn't jump off the small ring. Wrong!

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [DrAlexHarrison] [ In reply to ]

Mar 14, 21 11:17

Post #17 of 71 (1640 views)

You are probably just putting out too many watts. This rarely happens to professional cyclists, so you should probably dial it back to their sprints to the 1200 to 1800 watts range. Easier than replacing parts on your bike or, y'know, checking your chain length.

***

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [JasoninHalifax] [ In reply to ]

Mar 14, 21 11:31

Post #18 of 71 (1620 views)

JasoninHalifax wrote:

Doubt it was the frame. Sean Kelly, one of the best road sprinters of his era, raced on a Vitus 979 for years, and that thing was an absolute noodle compared to anything that cannondale has ever produced.

Those Vitus frames were really something. I swear you could get a good 2" of bottom bracket deflection under a reasonable load. We are soooo spoiled these days with stiff, light and reasonable comfortable bikes

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [grumpier.mike] [ In reply to ]

Mar 14, 21 11:48

Post #19 of 71 (1600 views)

grumpier.mike wrote:

Those Vitus frames were really something. I swear you could get a good 2" of bottom bracket deflection under a reasonable load. We are soooo spoiled these days with stiff, light and reasonable comfortable bikes

My first real race bike was a Japanese Vitus clone. It didn't take too long for the seat tube to debond from the bottom bracket. I didn't even notice for awhile; every thing was still in place but the bike was more "springy" than before. I actually liked it in sprints. Sucked on mountain descents though. Got an SL steel Olmo after that which wasn't much stiffer. Then got a Klein which was a whole 'nother world of stiffness and control.

My cheap Chinese carbon frame just keeps going. ~70k miles now and rides great.

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [DrAlexHarrison] [ In reply to ]

Mar 14, 21 12:08

Post #20 of 71 (1582 views)

DrAlexHarrison wrote:

jaretj wrote:

Classic sign of worn out chainrings.

Is there a way to visually inspect to confirm this? Telltale visual signs? Seems plausible, but I'm a little skittish to just throw on some stiffer/newer chainrings and go test sprints.

If it popped off at 1000W I'd more prone to try, but putting out 1500-2000W and having the chain come off is a pretty non-negligible chance of injury.

Thanks for your time!

A picture of them could help.

I went up Mt Lemmon twice this week :)

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [DrAlexHarrison] [ In reply to ]

Mar 14, 21 12:22

Post #21 of 71 (1562 views)

DrAlexHarrison wrote:

Chose the small ring because I was leery of chain popping off if using the big ring which happened earlier in the day at closer 35mph going downhill. No crash then, obviously. Figured surely the chain wouldn't jump off the small ring. Wrong!

Hmm, now that's interesting. I've had a mare with the chainline on my new 'dale' and it wanting to drop inside the inner ring. What chainset are you using? You say hollowtech cranks, but is this on a powermeter chainset, etc?

The other thing is that if you were cross chained, and you way rather than lube that can stiffen the chain and make it more likely to pop off on the inside of the inner (and outside of outer if cross chained). Note that the way you are doing has the mech needing to take up the most slack, and so the riskiest too.

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [M----n] [ In reply to ]

Mar 14, 21 14:21

Post #22 of 71 (1504 views)

Serious question... is chain length a possible cause of this? Off top of head, I can't figure out why this would cause issues. But I'm a very entry-level mechanic so please enlighten if this might genuinely be contributing to my problems! I had just assumed that if chain length was an issue I'd have had shifting issues much earlier on or some other symptom.

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
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Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [DrAlexHarrison] [ In reply to ]

Mar 14, 21 14:27

Post #23 of 71 (1493 views)

What does your rear derailleur look like when you are in small chainring and the smallest cog?

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [jaretj] [ In reply to ]

Mar 14, 21 14:33

Post #24 of 71 (1486 views)

jaretj wrote:

DrAlexHarrison wrote:

jaretj wrote:

Classic sign of worn out chainrings.

Is there a way to visually inspect to confirm this? Telltale visual signs? Seems plausible, but I'm a little skittish to just throw on some stiffer/newer chainrings and go test sprints.

If it popped off at 1000W I'd more prone to try, but putting out 1500-2000W and having the chain come off is a pretty non-negligible chance of injury.

Thanks for your time!

A picture of them could help.

I went up Mt Lemmon twice this week :)

Perhaps we should ride! My wife and I have been riding it every day the last couple weeks (except the snow day).

Dr. Alex Harrison | Founder & CEO | Sport Physiology & Performance PhD
-------------------------------------------------------------------------------------------------------------------------------------------------
📱 Check out our app → Saturday: Pro Fuel & Hydration, a performance nutrition coach in your pocket.
Join us on YouTube → Saturday Morning | Ride & Run Faster and our growing Saturday User Hub

Re: Is the frame too flexible? Or is it the chainrings? Something else? I went over the bars. [DrAlexHarrison] [ In reply to ]

Mar 14, 21 14:45

Post #25 of 71 (1472 views)

DrAlexHarrison wrote:

Perhaps we should ride! My wife and I have been riding it every day the last couple weeks (except the snow day).

Da-Dum. Da-Dum. Da-Dum. Da-Dum. Da-da-da -da-da -da-da -da-da -da-da -da-da-dum.

Those chainring teeth are worn to shark fins. Time to replace.

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