Hybrid instability at speed- me or tyres?

[ssray]

Recently started cycling after a loooong time off(20yrs), I bought a giant something disc braked hybrid about 3 years ago, it looked lovely on the garage wall, I hit 15odd stone(5ft8) being sheilded did not help, s far iv`e been cycling for about 10 days and have lost 6ish pounds and need a belt for the larger trousers that I bought
I started on the first day only doing about a mile before i nearly passed out, spots before my eyes etc
I have been out everyday since

Understanding that I probably ride a bit too stiff currently,going downhill at speed(26.1mph on the speedo) it or me wobbles ,it may be me as it feels quite fast and i`m used to motorbikes,but this is different
would a change of tyres help? currently I have the oe 700x32 giant sx3, usually on motorbikes the oe tyres are the cheaper end of the range
would going up to say a 700x40 help?
thanks Ray

[Tabs]

As you say, riding too stiffly. Relax your grip on the bars, and if you feel a wobble coming on, stop pedaling and bring both knees together towards the top tube. And relax more.

[TheDrownedApe]

You might have a slight buckle in one wheel?

A tyre might not be seated correctly in one spot resulting in an uneven rolling surface?

[ssray]

TheDrownedApe said:

You might have a slight buckle in one wheel?

A tyre might not be seated correctly in one spot resulting in an uneven rolling surface?

I could have, it's a brand new bike that's sat on the wall since I got it, I have done about 30 miles in 10 days since restarting cycling

[Maximus_Meridius101]

It sounds like you may have the ‘death grip’ on the bars. Try relaxing a bit, and letting the bike do the work. That might help. I’m assuming you’ve checked the security and condition of the wheels and axles / skewers, and checked the headset for excessive play, and that everything is turning smoothly.

[Mars]

ssray said:

Recently started cycling after a loooong time off(20yrs), I bought a giant something disc braked hybrid about 3 years ago, it looked lovely on the garage wall, I hit 15odd stone(5ft8) being sheilded did not help, s far iv`e been cycling for about 10 days and have lost 6ish pounds and need a belt for the larger trousers that I bought
I started on the first day only doing about a mile before i nearly passed out, spots before my eyes etc
I have been out everyday since

Understanding that I probably ride a bit too stiff currently,going downhill at speed(26.1mph on the speedo) it or me wobbles ,it may be me as it feels quite fast and i`m used to motorbikes,but this is different
would a change of tyres help? currently I have the oe 700x32 giant sx3, usually on motorbikes the oe tyres are the cheaper end of the range
would going up to say a 700x40 help?
thanks Ray

I see you're only in Stourbridge. I'm in Hanbury - just the other side of Droitwich. If you want me to look over your bike, I'd be happy to do so. I build and maintain bikes for fun. I could at least leave you with confidence in your machine.

[BugLebowski]

I've noticed some hybrids have horribly narrow handlebars which are probably a bonus for commuting but can't be great for stability at speed. Might be worth measuring to see what they are.

[ssray]

Mars said:

I see you're only in Stourbridge. I'm in Hanbury - just the other side of Droitwich. If you want me to look over your bike, I'd be happy to do so. I build and maintain bikes for fun. I could at least leave you with confidence in your machine.

Thank you very much, I'm going to persevere for a bit, try and go a bit further afield and see how I get on, I will dm you if it's not better in a week or two
Thank you

[ssray]

BugLebowski said:

I've noticed some hybrids have horribly narrow handlebars which are probably a bonus for commuting but can't be great for stability at speed. Might be worth measuring to see what they are.

The bars are quite wide, wider than the top bit of a racer

[Barchettaman]

BugLebowski said:

I've noticed some hybrids have horribly narrow handlebars which are probably a bonus for commuting but can't be great for stability at speed. Might be worth measuring to see what they are.

That’s more a hipster/courier thing.

[ssray]

I think I'm the problem, as far as I can work out my core strength is pretty bad, so I'm leaning on the bars far too much
Need to work on that

[irc]

Have you checked your tyre pressures? With your weight and 700x32 tyres they should be around 60-65psi rear and 55-60psi front . Personal preference to some extent but pressures that are far too low will affect handling.

https://www.renehersecycles.com/wp-content/uploads...

The other thing you can try is turn the bike upside down, spin the wheels, the stand behind and sight aling the tyres. There should be no side to side or up and down wobbling. When wheel are built a good wheelbuulder will be aiming for less than 1mm error.

If the tyres are wobbling it can either be a faulty rim which is not true or as suggested above an unseated tyre. As you can see in this pic a tyre not properly seated can be seen from the side. The reflective strip is far closer to the rim at one point.



The other possibility is that your bike has shimmy. Where the steering wobbles at certain speeds.

https://www.sheldonbrown.com/shimmy.html

[ssray]

irc said:

Have you checked your tyre pressures? With your weight and 700x32 tyres they should be around 60-65psi rear and 55-60psi front . Personal preference to some extent but pressures that are far too low will affect handling.

https://www.renehersecycles.com/wp-content/uploads...

The other thing you can try is turn the bike upside down, spin the wheels, the stand behind and sight aling the tyres. There should be no side to side or up and down wobbling. When wheel are built a good wheelbuulder will be aiming for less than 1mm error.

If the tyres are wobbling it can either be a faulty rim which is not true or as suggested above an unseated tyre. As you can see in this pic a tyre not properly seated can be seen from the side. The reflective strip is far closer to the rim at one point.



The other possibility is that your bike has shimmy. Where the steering wobbles at certain speeds.

https://www.sheldonbrown.com/shimmy.html

Thank you, I will have a look with that check list, tyres I normally set them around 80psi,thinking of fitting slightly wider tyres, just to check

[David_M]

I think that it is unlikely to be the wheels / tyres - you can ride ones that are surprisingly far out of true and hardly notice it (if they are really out of true then putting the bike upside down and spinning each wheel once will let you know).

As above answers, likely too tense and relaxing will help. Ride gentle hills and see if you can do that, then get faster. If you can ride no-hands then you know that you steer the bike more with your weight than with your hands anyway.

[ssray]

It's me, I went out today and within about a mile I could tell that I was putting too much pressure on the bars, forced myself to sit up a bit and it was much better, only problem is with the core strength of a Lettuce leaf I'm having to do a lot of reminding
I checked the wheels and they are straight, tyres are at 80psi
Thanks for the advice and replys
Ray