Bike handles poorly over about 23mph

[fossyant]

The RT58 v2 isn't a new fangled dutch bike is it - they are horrid ?

Something must be wrong as I've never had any bike that felt wobbly (other then test riding a friends dutch bike)

 

[Alan O]

rear wheel slightly out of true, had this on my Defy, was terrifying above 28 mph, replaced the wheels for better quality/lighter ones had 41 mph downhill out of it this morning, not a whiff of instability.

I was just thinking something along those lines - a wheel being a little out of true can certainly do that, while feeling fine at low speeds. And if, for some reason, the two wheels aren't perfectly in line you can get something similar (I had that happen once after an accident slightly misaligned my fork in a way that I hadn't otherwise noticed).

 

[gbb]

I assume this isn't a speed shimmy tincaman?

 

[Tin Pot]

Maybe above 23mph the sphincter tightens too much.

 

[Smokin Joe]

Headsets can be too loose even though you can't feel any slack. Release the pinch bolts and tighten the top cap down by half a turn.

I can't see how a loose headset can lead to any sort of wobble, unless it is so slack the front end is flopping about like a feather in the breeze. Half a turn out certainly won't cause that sort of issue.

 

[Ming the Merciless]

Was there a gusty cross wind blowing at the time?

 

[Ian H]

It might merely be a case of getting used to a new, twitchier bike.

 

[Globalti]

Conversely the other possibility is an over-tight or partially seized headset, which would make the bike feel as if it was rolling from side to side at higher speeds when steering is much finer than at low speeds.

 

[tincaman]

Thanks for the replies.

Medium sized frame, stem is 100mm, tyres are perfectly seated and wheels are true, handlebars are straight, wheels are Fulcrum 5's.

Wasn't a shimmy, no cross winds, conditions were good.
So I will be checking or resetting:

Headset
Wheels in the dropouts
Possible a spare wheelset

 

[Globalti]

Even a brindled headset bearing can cause the symptoms you described as the balls settle in the cavities they have worn in the races.

 

[tincaman]

Even a brindled headset bearing can cause the symptoms you described as the balls settle in the cavities they have worn in the races.

Brand new headset, angled cartridge bearings

 

[tincaman]

Update on this.
Got fed up with this and put the bike to one side to think about whether I was going to keep it.
In the meantime I bought a Diverge Comp frame and wheels from ebay to build up, after I finished I fitted 35mm Voyager Hyper tyres, went for shakedown ride and all was well.
I then decided to fit the 28mm Clement LCV tan wall tyres from the PX because they complimented the colour scheme, straight away the handling changed and was more twitchy, not as bad as the PX but noticeable. So I then fitted 28mm Ultremo ZX tyres back on the PX and immediately I could tell that things were back as they should be regarding the handling, which was much improved.
I still don't know how this is happening as the ZX tyres are just as light as the LCV's. I also tried different pressures over time to rule that out as well so I am a bit puzzled

 

[Deleted member 26715]

Twisted tyre

 

[steveindenmark]

Ride slower. Whats the rush?

 

[HLaB]

Or handlebars not straight, pointing slightly to one side.

Crash into the rider ahead a few times that'll sort it or maybe not