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wobbles - me or the bike?

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joolsss
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PostPosted: 19:54 - 30 Nov 2018    Post subject: wobbles - me or the bike? Reply with quote

Hi

Just getting back into riding after about 25 years! Got myself a '95 CB500, sounds lovely, looks lovely, local mechanic says its better than most of the new bikes he comes across.
So why when I am riding does it have a wobble quite a lot? Is it me? is it the bike? I have 2 new tyres (worn in now) mechanic can find no probs. It just feels every now and the like it is about to go from under me, I am losing confidence daily. Are all bikes a bit wobbly sometimes? Im no speed demon, maybe over cautious, I just dont know Sad
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Pigeon
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PostPosted: 21:38 - 30 Nov 2018    Post subject: Reply with quote

Small, light bikes with narrow tyres can more easily be moved by wind. But they don't wobble.

If you grip the bars too tight, any movement of you (wind or just road bumps) can translate to the bike moving. But I wouldn't call it a wobble. Try actively relaxing body and barely gripping the bars, does it still shake about.

A wobble might be:
Wheel bearings (wheels off ground)
Is there any movement of the wheel in its axle. Hold the top and bottom of wheel and push the side of the wheel at the top, pull side of the wheel at the bottom.

Headstock bearings (front wheel off ground)
Can you push/pull the front wheel forwards / backwards at all

Unbalanced wheel. Tyre fitters sometimes don't bother re-balancing wheel. But I've not actually met anyone who had it so bad the bike wobbled. But its a possibility.

Wheel alignment
Use a bit of thin string, wrapped round front tyre and pulled tight to the back wheel. As the string kisses the edge of the front, where does it end up at the back. It should be equal distances away from either side of rear wheel.

With the wheels aligned. Do the bars + yokes look straight.

Is the bike on its nose for some reason. A bike thats weighted over the front will be more twitchy. Check SAG. Possibly knackered shock + forks need an oil change.
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Riejufixing
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PostPosted: 21:53 - 30 Nov 2018    Post subject: Reply with quote

+ tyre fitment? Circles on rubber of sidewall above bead follow rim circumference in concentric circe?
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Teflon-Mike
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PostPosted: 21:56 - 30 Nov 2018    Post subject: Reply with quote

That's an old bike (Still younger than any of mine, but still!) Its also a [popular learner/commuter. Lots were bought originally as either cheap high mile hacks, for commuting/despatch, or by schools. They oft suffered not-such wonderful early lives, and sold on as 'cheap' early-milers or cheap hacks, suffered even more. On the other hand, dumbelling the spread, as trhe bike many more mature learners did thier DAS on, they were the bike they were familiar with when left to thier own devices, and oft bought new, used little, and sold on for very little money... SO, they can either be sore abused hacks, or they can be almost unused pampered garage trophies, and what's in the middle is not a lot.

If it looks great, likely to be at the unuised DAS newbie end of the spectrum, and things like wheel bearings and suspension and other 'dereliction decay' are more likely than it simply being worn out and bodged to oblivion.

But as 'cheap' bike... that top book, is likely only worth perhaps £1000, when even a set of 'budget' tyres are the around £200..... few are going to stick a brand new set of rubber costing 20 of the bikes resale, to sell on....

So what's this 'new' rubber?

Cheap crappy tyres would be a strong bet; wrong tyre pressures another, wheel bearing, shocks (another £200 for 'decent' plungers), fork oil and headraces bearings all make the lost of mechanical maledies that are fairly likely....

Holding on too tight, though IS pretty common.

One thing with the old CB500, though, it is a bit of a tank, it weighs in at around 200Kg if memory serves, and aught be pretty planted and stable.... why the schools loved them, so much....

Begs suggestion, if it wobbles, there is likely to be something wrong with it, even if you are death-gripping it...

Start with the tyre pressures, and have a look at the side-markings; doint just check make and model, check the date code too.. may have been newly fitted, that dont mean the tyres are so young....
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kgm
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PostPosted: 22:01 - 30 Nov 2018    Post subject: Reply with quote

Do you have an experienced friend who could ride it?
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Sister Sledge
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PostPosted: 22:22 - 30 Nov 2018    Post subject: Reply with quote

kgm wrote:
Do you have an experienced friend who could ride it?


This ^^
Try to get someone else to have a go and who is experienced. Their riding style or even their weight should answer some questions or eliminate others.

I'm also wondering if it's particular surfaces where the wobble coming? What about certain speeds??
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M.C
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PostPosted: 22:34 - 30 Nov 2018    Post subject: Reply with quote

Assuming the local mechanic's correct and the bike's fine, grip the tank with your knees. If you have a death grip on the bars and if you're nervous the bike will behave nervously.
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colink98
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PostPosted: 09:33 - 01 Dec 2018    Post subject: Reply with quote

the road surface can also have a big effect.
on my journey there are several roads where i filter and as well as the dividing white lines there are also joins in the tarmac.

even now it can feel like the bike is searching for a bit of grip.
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Ian193
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PostPosted: 11:12 - 02 Dec 2018    Post subject: Reply with quote

Are the tyres inflated to the correct pressure my scooter feels skittish if the tyres are a little bit softer than they should be (I do check them and the oil once a week)
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recman
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PostPosted: 12:43 - 02 Dec 2018    Post subject: Reply with quote

Whereabouts are you? I'm fairly sure someone on here will pop along and have a go.
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stinkwheel
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PostPosted: 13:08 - 02 Dec 2018    Post subject: Reply with quote

Tyre pressures may be relevant. They changed their mind on standard tyre pressures a bit back. Must have been a reason for it.

33psi rear, 29psi front.

The sprocket carrier bearing can also collapse with very little sign that anything is amiss.

As above, I would get an experienced rider to have a go on it. Pay particular attention to where you are when this wobble appears, what speed you're doing, wether you are braking or accelerating.
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talkToTheHat
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PostPosted: 17:49 - 02 Dec 2018    Post subject: Reply with quote

Failing swingarm bearings might also cause kind of a wobble. More of a weave over bumps. Loose headstock bearings will cause a rocking and perhaps a clunking over braking.
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Kawasaki Jimbo
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PostPosted: 18:38 - 02 Dec 2018    Post subject: Reply with quote

stinkwheel wrote:
Tyre pressures may be relevant. They changed their mind on standard tyre pressures a bit back. Must have been a reason for it.

33psi rear, 29psi front.

Haven't most modern tyres standardised at 36F/42R? I'd ignore what the bike manual suggests because it will be based on specific tyres which are no longer available.

I think we need to know what the OP means by "wobble." High speed weave, slow speed straying from a straight line, 50p-ing on roundabouts?
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trevor saxe-coburg-gotha
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PostPosted: 20:18 - 02 Dec 2018    Post subject: Reply with quote

Another vote for PSI from me as well.

I've done best part of 50k miles on CB500s over the last few years and I only ever ran two kinds of tyres. EITHER Avon Road Riders OR Michelin Pilot Activ.

The former need to be run at book pressure of 29 front and 33 rear. However, the latter can feel quite sketchy at that PSI though, and need to be 34 front and back.

I appreciate that tyre pressure is a really obvious possibly insulting variable to point to. But it does sometimes get overlooked when switching from one make to another, and owners assume that book pressure will remain constant. It may. It may not.

BTW if you have a choice between the Avons and the Michelins, get the Michelins. They're so much better it's scarcely believable.
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recman
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PostPosted: 22:23 - 02 Dec 2018    Post subject: Reply with quote

Op has wobbled into a ditch.
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Sister Sledge
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PostPosted: 09:19 - 03 Dec 2018    Post subject: Reply with quote

I tried to be funny and looked for an image of a man made of jelly - don't look. Seems it's also a type of silicone penis extension Sad
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joolsss
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PostPosted: 12:35 - 03 Dec 2018    Post subject: Reply with quote

Hi,

Thank you for all of your replies, I have been looking into some of these.

What I have noticed upon doing some of the checks suggested, is that there when I spun my rear wheel, it struggles to do one revolution.
Then I noticed that there is some noise like brake squealing when I am pushing my bike out of the garage. then today, whilst waiting at lights, I could smell a burnt rubber/possibly oil smell, not massively strong, and cannot smell it while riding.

Could these all be connected and could they cause instability?
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joolsss
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PostPosted: 12:41 - 03 Dec 2018    Post subject: Reply with quote

Also, I am in Coventry if anyone fancies having a go on it for me? Thumbs Up Very Happy
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stinkwheel
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PostPosted: 14:19 - 03 Dec 2018    Post subject: Reply with quote

joolsss wrote:
Hi,

Thank you for all of your replies, I have been looking into some of these.

What I have noticed upon doing some of the checks suggested, is that there when I spun my rear wheel, it struggles to do one revolution.
Then I noticed that there is some noise like brake squealing when I am pushing my bike out of the garage. then today, whilst waiting at lights, I could smell a burnt rubber/possibly oil smell, not massively strong, and cannot smell it while riding.

Could these all be connected and could they cause instability?


Possibly. If the brakes are binding, it would definately cause problems. Front brake in particular. That said, they will often flash-rust overnight and bind slightly when first taken out causing squealing and some resistance to turning that goes away after a few metres. Does it coast easily once it's rolling?

I usually check for lightly binding brakes by riding for a bit without using the brakes then stopping without using the brake I want to check and seeing if the disc is hot. Do this by flicking spit/water onto it, not by touching it, even with gloves on. If they are binding, the disc will be hot (and I mean HOT, will burn you through motorbike gloves).

@Jimbo, most bikes have reasonably standard tyres, CB500 have oddball tyre sizes and most of the available ones are bias belted. The roadriders we just fitted to Mrs stinkwheels one inspire confidence.

It occurrs to me that I've previously had Bridgestone BT45 tyres go a bit funny when the front gets worn (but not yet worn out) with a tendancy to track along linear markings on the road and feel a bit vague.
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Kal
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PostPosted: 05:18 - 04 Dec 2018    Post subject: Reply with quote

M.C wrote:
Assuming the local mechanic's correct and the bike's fine, grip the tank with your knees. If you have a death grip on the bars and if you're nervous the bike will behave nervously.


This, there is so much to a bikes control input than the peddles and handlebar controls. Your whole body controls the bike.
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barrkel
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PostPosted: 13:35 - 04 Dec 2018    Post subject: Reply with quote

Kawasaki Jimbo wrote:
Haven't most modern tyres standardised at 36F/42R? I'd ignore what the bike manual suggests because it will be based on specific tyres which are no longer available.

Different bikes can have different geometries and put different ratios of weight on front vs rear.

My Brutale specs 2.3 bar front and rear (about 33 psi).
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Kawasaki Jimbo
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PostPosted: 13:49 - 04 Dec 2018    Post subject: Reply with quote

barrkel wrote:
Kawasaki Jimbo wrote:
Haven't most modern tyres standardised at 36F/42R? I'd ignore what the bike manual suggests because it will be based on specific tyres which are no longer available.

Different bikes can have different geometries and put different ratios of weight on front vs rear.

My Brutale specs 2.3 bar front and rear (about 33 psi).


If that works for you then OK. Here's my point though: https://www.bridgestone.co.uk/motorcycle-tyres/battlax/tyres/
A search for your bike fitment shows 2.5F/2.9R on modern tyres.
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M.C
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PostPosted: 16:42 - 04 Dec 2018    Post subject: Reply with quote

Kawasaki Jimbo wrote:
barrkel wrote:

Different bikes can have different geometries and put different ratios of weight on front vs rear.

My Brutale specs 2.3 bar front and rear (about 33 psi).


If that works for you then OK. Here's my point though: https://www.bridgestone.co.uk/motorcycle-tyres/battlax/tyres/
A search for your bike fitment shows 2.5F/2.9R on modern tyres.

I kinda agree with barrkel, most bikes I've seen run the same front and rear or close pressures. The Street Striple seems to be the exception*, where you run 34/42 psi, when with the Daytona (I believe) it's 34/36. FWIW not many owners seem to run 42 psi in the rear.

*obviously there may be others but I've better things to do than research tyre pressures Smile
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trevor saxe-coburg-gotha
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PostPosted: 08:24 - 05 Dec 2018    Post subject: Reply with quote

I honestly thought 36 42 was pretty standard for sports bikes.
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M.C
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PostPosted: 12:05 - 05 Dec 2018    Post subject: Reply with quote

trevor saxe-coburg-gotha wrote:
I honestly thought 36 42 was pretty standard for sports bikes.

I don't do sports bikes Folded arms I was surprised the Street Triple ran massively higher rear pressures than the Daytona; that's the stock ST, I'm not sure what the R model runs I imagine it would be the same as the Daytona (same rear shock AFAIK).

Stupid question time (for a change) Smile Is that what gives them the sporty turn in? Why don't you just run higher pressures in the rear on any bike? Any bike that runs the same pressures F&R I always go a couple PSI higher in the rear.
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