Video of my chain slipping off while sprinting today

[trpnhntr]

I’d also point towards the front chain ring - on some of the…more flexible front chain rings it is fairly easy to throw the chain in the 52 or 53/11 combo. Start at a slow speed and low cadence in that gear and put out maybe 450-500 watts and you can throw the chain. Obviously you can also do this at speed in a high cadence, but it’s a safer way to test if the front chain ring is the culprit

That save though…

[Nate_Pearson]

@djwalker1260

What was your rpm? My experience is that small cogs and high force make it more likely for the chain to skip. Back in the old days (late '70s and early '80s) when 6 and 7 speed were brand new you could make a chain skip by putting huge pressure on the smallest (13T and 14T) cogs. Often that would rip teeth off of the cogs. This is the reason that I never use the smallest cogs at very low rpm if I can avoid it.

It was low. We were doing low cadence/high force spin ups. Next time I will do those from a smaller gear and lower speed!!

[Nate_Pearson]

I’m using Praxis rings with a YBN chain. I’m going to switch to a Dura-ace chain.

Praxis is known for being really stiff, so that’s a bummer if it’s the chain ring.

[Nate_Pearson]

@djwalker1260

I would also check for burrs or bent teeth on the chainring. I had a couple of burrs on my large chainring that would partially lift up the links. I could hear and see the chain jumping a little every revolution of the cranks. I filed off the burr and everything was fine. BTW- I think that the burrs arrived when I dropped the crank during servicing.

Great tip, I will check it out.

[Nate_Pearson]

@trpnhntr

I’d also point towards the front chain ring - on some of the…more flexible front chain rings it is fairly easy to throw the chain in the 52 or 53/11 combo. Start at a slow speed and low cadence in that gear and put out maybe 450-500 watts and you can throw the chain. Obviously you can also do this at speed in a high cadence, but it’s a safer way to test if the front chain ring is the culprit

I should try this on the trainer to see if I can get it to happen again (after I make a change, like new chainring or different chain). Worse case is a banged up knee.

[Nate_Pearson]

Mystery solved. I definitely have a slight 1mm bend in my front chain ring.

I have Praxis chain rings on Specialized cranks. I haven’t crashed or anything and the chain ring is pretty new. The question is did I bend it during the ride or was it bent before?

[Nate_Pearson]

Here it is at full speed

Chain Slipping During a Sprint

[trpnhntr]

@Nate_Pearson

I should try this on the trainer to see if I can get it to happen again (after I make a change, like new chainring or different chain)

Not a bad idea, but you do have some variable there with how the backend of the bike is secured. It’s probably a good first test, but it doesn’t prove it won’t be a problem outside. Doing it at a low cadence, high force combo outside is relatively safe and a way to test that flex

[WTriathlete]

Well held @Nate_Pearson

I’m sure @Jonathan’s tip to “stay up” helped a lot

[Nate_Pearson]

I didn’t think of it until he said it .

[justin]

How many watts?
Nate: all of the watts

[Alen]

That is a lot scarier in full speed than in slow motion. I think my heart sank twice watching those two videos.

[cam]

Saw this on Jonathan’s Instagram… glad you kept it upright Nate!!

Something I’ve been doing in training that’s helped me identify drivetrain related issues and feel more confident in my equipment sprinting is standing starts. Big ring in the front, pop it in the 13 in the back and sprint full gas from a complete stop. You should hear or notice anything that’s not right before you really get on top of the gear. I would start with a controlled effort first to be sure

[Nate_Pearson]

That’s a great idea. If it does pop you’re not going fast so it won’t hurt as much.

[lorenzBrandl]

Respect for catching that…
How fast where you going?
A reason for that kind of chain slip could also be a loose derailleur hanger.
My chain also slipped in the end of April. Cost me the joints of two fingers…

[Nate_Pearson]

Ouch!!!

I think I started at 20 mph

[larskoelle]

Glad you saved that!
Seems like we have similar handling skills I slipped out of my pedal this week, destroyed my leg with the big ring but didn’t crashed into the car coming along on the other side of the road;-)

[Nate_Pearson]

Omg! What pedal? Why did it come out?

Glad to hear you’re okay!

[larskoelle]

Thanks a lot. P1 pedals, I honestly don’t know why I slipped out of them. I am going to double check shoes and pedals tomorrow, but I guess it was just because I was putting out 1000 w while sprinting up a bridge. Probably bad cycling technic as well

[Dave]

Well held!