BSA Owners' Club Forum

General => The Star and Garter => Topic started by: MICKREEVES on 25 February, 2017, 08:14:24

Title: Balancing on a bike
Post by: MICKREEVES on 25 February, 2017, 08:14:24
My C15 ss balances well. I can turn round in my narrow yard, without putting a foot down. (old trials rider).
On my 250 Virago, (My first ride after have a new knee fitted) I was turning round in a side road when forks
reached full lock, and over I went. I was trapped under the bike with the engine revving in gear for a few seconds.
Question - when you reach full lock on a bike, is it still possible to retain your balance?? (remaining seated)
Mick
Title: Re: Balancing on a bike
Post by: Arthur on 25 February, 2017, 10:13:26
Mick.

As mentioned in a previous post, all motorcycles suffer from the phenomenon of 'wheel drop'. At slow speed, as you turn the steering to one side, the height of the front suspension will drop because of the steering geometry which will create a force tending to make it turn even further. The greater the bike's trail, the greater is the force. Above a few mph, this force is countered by the gyroscopic forces from the faster rotating front wheel, which tends to keep the bike moving in a straight line.
Your Virago has a relatively large trail and hence wheel drop is very pronounced - hence, it's not an easy bike to manoeuvre at slow speed.

In answer to your question, I think it should be possible to maintain your balance on a bike at full lock providing the front brake is applied to stop it moving. I'll try it on my trail bike later!
Title: Re: Balancing on a bike
Post by: Arthur on 25 February, 2017, 11:46:38
If you were referring to balancing on the bike when it was moving slowly then this probably relies more on the movement of the handlebar to counter any tendency of the bike to fall to one side. However, once you reach full lock, you would then have reached the limit to which you can counter a falling motion to that side and it would then be time to put your foot on the ground to steady the bike.
Title: Re: Balancing on a bike
Post by: MICKREEVES on 07 March, 2017, 18:55:00
I guess upper body sideways movement would help.
Title: Re: Balancing on a bike
Post by: EDDIE SIMPSON on 07 March, 2017, 23:28:07
i was taught to figure of eight on full lock with knees out 90 degrees from body , like scrambling. it does work providing your not awaiting hip ops etc. and your knees are good.
Title: Re: Balancing on a bike
Post by: MICKREEVES on 10 March, 2017, 18:51:46
On the question of front wheel trail, I wondered if cutting a V slot in the frame underside, then closing and welding up, to give a steeper fork angle and less trail, would  cure the problem?
The other characteristic of my Virago, is the way its track moves about on the road. It takes concentration to hold a line. My C15 holds well without effort.
Title: Re: Balancing on a bike
Post by: STAR TWIN on 11 March, 2017, 06:40:32
It might cure one problem but is might well pose others - beware the law of unintended consequences. Would your insurers be happy with an unauthorised alteration to your frame geometry?
Title: Re: Balancing on a bike
Post by: JulianS on 11 March, 2017, 09:35:45
Tampering with a bikes geometry is potentially dangerous to all road users.

Suggest sell it and buy a bike more suitable for your intended use - maybe a trail type?
Title: Re: Balancing on a bike
Post by: Arthur on 11 March, 2017, 12:08:05
The other characteristic of my Virago, is the way its track moves about on the road. It takes concentration to hold a line. My C15 holds well without effort.
I think there's something wrong with the suspension or wheel alignment on your Virago - a larger trail should make it want to go in a straight line and not want to go left or right.
Title: Re: Balancing on a bike
Post by: MICKREEVES on 13 March, 2017, 07:03:30
I rode the virago yesterday, first for four months. (Knee replacement)
It was not as bad as I thought. Actually quite ok on the straight. I was worried that my destination had a pebbled car park.
CouldIi balance, and keep my bad leg up on the high set rear brake? Front brake no good on loose pebbles.
Actually, I managed ok, with a squerilly path out afterwards.
I want to move the foot rest back to a normal position, but it wont be easy.
I have looked for alternative bikes, which must be about 300 lbs weight, with good performance and lowish price. Fourstroke preferred.
The C15 would be ideal, if I could get it to perform as it should!
Mick