Wobble on zipp 404 when breaking

Amulya Parthasarathy

Team,
I'm experiencing wobble on my TT bike with Zipp 404 clinchers while breaking on high speed descends (30+ mph). I don't experience any wobble on flats on high speeds (close to 30mph) but only happens on descends which I just realized that it happens only while breaking. I just got a new Cervelo P5 six and the issue happens with the same set of wheels. 

Anyone experience such issues with carbon wheels? Any thoughts on what could be the issue here?

Al Truscott

If your 404s were purchased between May 2010 and Jan 2015, they may be subject to a recall regarding the hub. Not saying this is related to your issue, but it's worth checking out:

http://www.zipp.com/_media/pdfs/support/SRAM_ZIPP_V6.V7.V8_Customer_Notice%203_16_2016.pdf

Amulya Parthasarathy

Thanks Al. I did have my front hub replaced through the recall last year. I was hoping that would have fixed the issue but it didn't. Then I was under the impression that it could have been my old Specialized Transition TT frame that was the cause of the issue and I didn't ride my TT bike after that. Last week I got a new P5 six and the wobble is happening on my new bike as well with the same set of Zipp 404.

I was curious to hear if there were others that have seen similar issue with carbon wheels and if this was a common problem. Also anyone know what is the life expectancy is a wheel such as zipp 404's?

I will have my wheels taken to my local bike shop and checked if they are true.

DAVID RICHMOND

check your headset, same thing happened to me: only with front 404, only on descents, when braking, but it was due to a small play in the headset. I've had 404 for more than 12 years, pretty much bomb proof IMO (but i'm only 60kg)

Amulya Parthasarathy

Thanks for the tip David. I will have that checked. Sounds very similar to the issue I'm experiencing 

DAVID RICHMOND

keep us posted

Brian Smith

@Amulya Parthasarathy
Just a quick note if you have not figured it all out yet, I had a similar issue recently on a newer 404 front and it turned out that I needed the wheel to be trued up, as it was slightly off and was more noticeable at higher speeds/breaking.  When I spoke to the company they said yes, the wheels are durable and strong, but road surfaces that are rougher tend to make them a little untrue, especially due to the reduced spoke count.  

Amulya Parthasarathy

Thanks for the note Brian. There were a few things off on my bike.
1. The wheels were slightly off and had to be trued off. The bike shop thinks that it was very marginally off and that shouldn't have caused a wobble, but never the less I have it trued up now.
2. The handle bar was slightly off and wasn't at 90 degrees with respect to the front wheel. They suspect that I may have been over correcting due to that and causing wobbles.

I haven't got to ride outside on routes that have long fast descends yet that would typically cause the wobble, so I would hold off and confirming that the issue is fixed as of yet. Short descends seem to be fine and I don't think I had a problem with them before.

Another theory that my bike shop had was incorrect weight distribution. My seat clamp is sitting at the very end of the Cervelo P5-sex seat post towards the end of the bike. My saddle however is however somewhat centered so I'm not sure why they had the clamp sitting at the very end. They didn't want to change that yet and wanted me to give the wheel trueup and handle bar adjustment a try.

I will keep you guys posted on the outcome.

DAVID RICHMOND

Is that a new cervelo model? Sounds kinky

Amulya Parthasarathy

It's a 2014 Cervelo P5 Six model but I just got the bike brand new 6 weeks ago.

Brian Smith

I got the same back stock model about 8 weeks back....but only the frame, fork, cockpit and breaks...Cervelo was offering the back stock to shops to sell from what I was told, that is how I was able to get the 2014 model fairly inexpensive, well for our sport that is...ha.

DAVID RICHMOND

Was referring to this "Cervelo P5-sex" in your comment

Amulya Parthasarathy

LOL I didn't even realize there was a typo.

Dino Sarti

Sometimes it is the brake track.  There is special little "sander" the shop can use to buff out any little rise in the braking surface.  I had a riding friend experience the same thing.  The shop sanded out a little high spot on the braking surface and it totally went away.

Amulya Parthasarathy

Thanks for the tip Dino. I willl get that checked out.