Planet X pro carbon speed wobble, questions
zefs
Posts: 484
Hello, I just received my new bike setup today from the LBS who transfered the components from my Scott Speedster 20.
I got the Planet X Pro Carbon (the classic, not newer version) frameset and I noticed a wobble effect on the front end. I only did a few km's to test the new setup and when I moved the handlebars from one side to the other quickly/repeatedly (similar effect to what happens when going over cobblestones I'd imagine) the whole bike wobbles.
Is this a normal behaviour, are there any ways to eliminate it or is it the fork itself?
When the handlebar is straight there is no wobble at all, so I did this test while not riding:
* Keeping the handlebar/bike straight I tried to shake the top tube with my hand - no issues.
* Steering the handlebar to either side and applying the same force the whole frame vibrates.
Also, while I was doing the test ride there was 16-17km/h headwind and didn't notice any issues meaning it shouldn't be an issue, but I imagine in a high speed corner if a bump or wind is encountered while the handlebar is turned it could be a problem. Actually I felt less confident on this setup in comparison to the Scott and I was wondering if it's possible to fix this issue?
Here's some comment on this matter from the bikeradar review in 2010 (it's a different model but I thought of posting the info incase it helps):
http://www.bikeradar.com/gear/category/bikes/road/product/review-planet-x-sl-pro-carbon-10-36958/
I got the Planet X Pro Carbon (the classic, not newer version) frameset and I noticed a wobble effect on the front end. I only did a few km's to test the new setup and when I moved the handlebars from one side to the other quickly/repeatedly (similar effect to what happens when going over cobblestones I'd imagine) the whole bike wobbles.
Is this a normal behaviour, are there any ways to eliminate it or is it the fork itself?
When the handlebar is straight there is no wobble at all, so I did this test while not riding:
* Keeping the handlebar/bike straight I tried to shake the top tube with my hand - no issues.
* Steering the handlebar to either side and applying the same force the whole frame vibrates.
Also, while I was doing the test ride there was 16-17km/h headwind and didn't notice any issues meaning it shouldn't be an issue, but I imagine in a high speed corner if a bump or wind is encountered while the handlebar is turned it could be a problem. Actually I felt less confident on this setup in comparison to the Scott and I was wondering if it's possible to fix this issue?
Here's some comment on this matter from the bikeradar review in 2010 (it's a different model but I thought of posting the info incase it helps):
http://www.bikeradar.com/gear/category/bikes/road/product/review-planet-x-sl-pro-carbon-10-36958/
But when it came to cranking up the gears, getting out of the saddle and sprinting, some of the riders were really able to feel the front end flexing. The fork is remarkably light for the price, but also the steerer tube came fitted with a couple of spacers and it’s possible that cutting down the steerer and whipping out those spacers might have tightened the front end and reduced some of the flex.
0
Comments
-
I only ever felt that the fork could have done with being a bit stiffer going downhill, to help the bike track quicker. Just riding along I never experienced anything like you have.
It's hard to know from your description what is causing the behaviour you describe but perhaps something else might be to blame, like a loose headset.0 -
Thanks for the reply, today I will try it on downhill and see how it goes.
Riding along it doesn't happen by itself, you have to "wobble" handlebar from side to side, ofcourse you never do that when riding a bike, but I thought when taking a corner if a bump or wind appears it may cause same effect. Will also take it to the LBS for further inspection.0 -
Headset?0
-
I raced a season on my PX pro, it was a flexy old hector - so this may be it. I'd cerainly check its setup OK.Insert bike here:0
-
You mean size or brand, does the image help?Headset?
I went to the LBS today and he mentioned that it happens because of how the frame/fork combo is built and there isn't anyway to set it up so it stops wobbling (the headset wasn't loose or anything). I did a 54km/h downhill afterwards and didn't notice any issues and the whole ride was 55km so I guess I will just get used to it.I raced a season on my PX pro, it was a flexy old hector - so this may be it. I'd cerainly check its setup OK.
Other than that I am happy with the transfer from the alu to carbon as it seemed to dampen the road surface more giving a smoother ride, accelerate faster and it's easier to pedal (also changed the chainset to ultegra).0 -
" when I moved the handlebars from one side to the other quickly/repeatedly (similar effect to what happens when going over cobblestones I'd imagine) the whole bike wobbles.
Is this a normal behaviour, are there any ways to eliminate it or is it the fork itself?
When the handlebar is straight there is no wobble at all,"
I've never thought to do that on a bike - and I don't see that its what happens when going over cobbles - you keep the bars straight.
As you say - it rides fine unless you dick around turning the bars like that and I can't think of an occasion when you would - so I'd be happy to go with it as is ?0 -
" when I moved the handlebars from one side to the other quickly/repeatedly (similar effect to what happens when going over cobblestones I'd imagine) the whole bike wobbles.
Is this a normal behaviour, are there any ways to eliminate it or is it the fork itself?
When the handlebar is straight there is no wobble at all,"
I've never thought to do that on a bike - and I don't see that its what happens when going over cobbles - you keep the bars straight.
As you say - it rides fine unless you dick around turning the bars like that and I can't think of an occasion when you would - so I'd be happy to go with it as is ?
Well as I said an occasion would be on a sharp turn if you meet with a road object or wind. Since the front end is not stable when steering it's more likely to have a fall. On the Scott I could take turns with more confidence and it had a carbon fork as well.0 -
So it wobbles when you turn the bars, or turn the bars repeatedly - which is what you said - and wouldn't happen in real life ?0
-
So it wobbles when you turn the bars, or turn the bars repeatedly - which is what you said - and wouldn't happen in real life ?
Again, yes it does and the reason is that it's not stiff on the front end when the handlebars are turned (for some reason) but if you hit an object like a rock for example that instability could cause trouble.
Right now I have the Fulcrum Quattro wheels on it which are stiff, not sure how it would work with other wheels but will test with the Scott's as well.0 -
When cornering at speed you barely turn the bars anyway.
I've never experienced any sketchiness or speed wobble in thousands of miles on my PX Pro Carbon0 -
When cornering at speed you barely turn the bars anyway.
I am not sure what's so hard to understand as I explained few times already that there are other parameters that could turn the bars as I said.
What's interesting is that it behaves like that only when the handlebar is turned to one side or the other (even with the bike static), maybe someone could give an explanation to this matter and if it's possible to improve it.
Maybe it has to do with the headset being too "heavy" for the fork/front part of the frame?
Another reason could be the frame size? I got the Large one, which has the 57cm top tube. Maybe the smaller sizes behave differently.0 -
Is the front wheel secured properly ? It might not vibrate if straight ahead - but if its sideways and not tight it might rattle a bit. What degree of turn on the bars are we talking ?0
-
I'm not sure I understand what you're actually doing to the bike and what is happening as a result. Perhaps a video or photos would help illustrate your issue?0
-
Is the front wheel secured properly ? It might not vibrate if straight ahead - but if its sideways and not tight it might rattle a bit. What degree of turn on the bars are we talking ?
Yeah the wheel is secured properly and it's centered correctly (checked by the mechanic and myself).
About the bars when turned all the way to one side, yes I know...you never do that while riding but that doesn't mean that it doesn't happen on the road, it just feels quite loose. Someone on this forum described it as "spaghetti" which I'd say is accurate. I think it has to do with the weight in the front end and being a large frame there is something wrong in the weight distribution. When I put pressure on the drops it stabilizes a bit, but none rides like that (as it would hurt the hands if you always apply pressure).I'm not sure I understand what you're actually doing to the bike and what is happening as a result. Perhaps a video or photos would help illustrate your issue?
A video wouldn't help but you can test it on your PX (what size do you own?) as I describe on first post.
Turn the bars all the way to one side with the bike static then grip the top tube and shake it with one hand, on mine the whole frame is vibrating for a few seconds when I do that.0 -
I've just tried it with one of my bikes and I couldnt detect any difference.
Maybe its a cable thing ? Cables slack and able to vibrate ?
But as we've all said - that's never going to happen in real life so don't worry.
If your wheel is at 90degrees then any wobble is the least of your worries. You're going down....
And its clearly NOT a speed wobble - so your title is probably confusing people too.0 -
It's a large. When I get home this evening I shall turn the bars to 90 degrees, give the top tube a shake and see what happens. As others have said, I'm not sure it matters what happens given this is never going to happen when riding it.I'm not sure I understand what you're actually doing to the bike and what is happening as a result. Perhaps a video or photos would help illustrate your issue?
A video wouldn't help but you can test it on your PX (what size do you own?) as I describe on first post.
Turn the bars all the way to one side with the bike static then grip the top tube and shake it with one hand, on mine the whole frame is vibrating for a few seconds when I do that.0 -
zefs - received you're pm regarding this. I don't really have anything to add I'm afraid. As mentioned in the other thread mine is a pretty normal setup, 110mm stem and 25mm of spacers and I've never had any issues with it whatsoever. Its been a great bike for the 5 years that I've had it and I'm only changing to another PX frame for this summer because I got it cheap in the xmas sale. While they might not be the most modern of designs they are cracking bikes for the price that PX churns them out for... Full ultegra for £1100 takes some beating. Hope you solve you're issues, but as others have said, in normal everyday riding I haven't noticed this.0
-
^^This, it is as enjoyable to ride as the far more expensive Canyon I ride.When cornering at speed you barely turn the bars anyway.
I've never experienced any sketchiness or speed wobble in thousands of miles on my PX Pro Carbon0 -
zefs - received you're pm regarding this. I don't really have anything to add I'm afraid. As mentioned in the other thread mine is a pretty normal setup, 110mm stem and 25mm of spacers and I've never had any issues with it whatsoever. Its been a great bike for the 5 years that I've had it and I'm only changing to another PX frame for this summer because I got it cheap in the xmas sale. While they might not be the most modern of designs they are cracking bikes for the price that PX churns them out for... Full ultegra for £1100 takes some beating. Hope you solve you're issues, but as others have said, in normal everyday riding I haven't noticed this.
Thanks for the reply, I guess your's is a different model then since you've had it for 5 years?
Is there any way to tell? on mine the fork says 2014 if I am not mistaken.0 -
Yours will be the same frame and fork as ravey1981's bike and mine, the only real change has been the colours available.0
-
Yours will be the same frame and fork as ravey1981's bike and mine, the only real change has been the colours available.
Then I am not sure why they react differently since it's the same frame. Could it be that mine is defective, does carbon get flexier after time passes?0 -
The Pro Carbon can feel very light on the front end when you first ride it but after a few rides it's not even noticable. Shorter stems can sometimes make the steering feel more jittery IME.
Carbon AFAIK does not get flexier with age otherwise mine would feel flexier as it is a few years old, this bike has been available in this guise for a good few years.0 -
Removing the front wheel and the wobble doesn't happen when the handlebars are turned, not sure if that says anything.0
-
Make sure the QR is tightened appropriately and that there is no play in the wheel bearings?
Also I'm not sure if its been mentioned yet, but make sure the headset is properly tightened.0 -
Nope, same exact frame and fork, different paint job. Planet X is being a bit cheeky in marketing these as the "new" pro carbon if you ask me....0
-
Removing the front wheel and the wobble doesn't happen when the handlebars are turned, not sure if that says anything.
Possibly indicates that the front wheel isn't tight in the forks or there's some play in the hub ? So either way its not the frame.0 -
Removing the front wheel and the wobble doesn't happen when the handlebars are turned, not sure if that says anything.
Possibly indicates that the front wheel isn't tight in the forks or there's some play in the hub ? So either way its not the frame.
I tightened it as much as possible (without closing the QR) just to see what happens but the behaviour is the same. I also tried my older wheel but same thing so I guess that it's not a wheel issue, there is no play in the hub either :?0 -
And no play in the headset ? Lock the front brake and rock the bike back and forth ? There shouldnt be any play...0
-
@ OP try taking the front wheel out and rotating the end caps clock-wise. Some are threaded on, if yours are this will eliminate any play in the axle between them. If they are backed off, the Qr's clamp up against them leaving the free play the other side of them untouched.0
-
And no play in the headset ? Lock the front brake and rock the bike back and forth ? There shouldnt be any play...
There is no play when doing that.@ OP try taking the front wheel out and rotating the end caps clock-wise. Some are threaded on, if yours are this will eliminate any play in the axle between them. If they are backed off, the Qr's clamp up against them leaving the free play the other side of them untouched.
As I said the wheel is secured correctly.
I guess I'll have to test another fork and see how it behaves.0
