Some spokes in the bike hire wheel

Many people absolutely love Boris Johnson's bike hire scheme and it's really popular with around 22,000 trips taken a day.

It also has a loyal following with many web forums like borisbikes.co.uk.

However, there have been problems bubbling along for some time including:

• Faulty bikes

• Call centre queries

• Overcharging on accounts

There's also been some concern that the experience for casual users isn't ideal, especially when using a credit card.

In fact, I have found out the contractor Serco has been penalised £5m for not meeting targets set in its contract and has had payments withheld.

Insiders have also told me that the current model doesn't work, especially around mainline train stations where docking stations empty straight away.

They said that the only way for the system to work and for docking stations to be refilled by users is to charge more at rush hour to limit demand.

I can't see that happening in the run-up to the mayoral election, but it is quite an admission.

Another interesting point is that there's been an big increase in casual users.

Every weekday 20% of trips are now casual users with that rising to 50% at the weekend. Transport for London (TfL) expect that to rise even more in the summer.

By serving a critical improvement plan and a sending a team into Serco to try and help - TfL hope they can sort out these problems soon.

How have you been finding the hire scheme? Has it got worse recently?