Cycle Tube Network?

Could abandoned Tube stations and tunnels be solution to Cycle Safety.

They are the subject of fascination for many Londoners, but disused Tube stations are set to be sold off for more lucrative purposes.
Transport for London (TFL) is planning to invite companies to bid to convert the abandoned spaces into tourist attractions including hotels, shops and museums, the London Evening Standard reported.
There are at least 40 derelict Overground and Underground stations, as well as hundreds of old horse tunnels snaking deep below the capital.
However there may be a much better use for the disused tunnels.
TFL and The Mayor are planning to create cycle routes by closing off lanes to traffic which will significantly increase congestion.
Most  pollution is created when vehicles are stop starting in traffic so an increase in congestion will significantly increase pollution.
The many miles of disused tunnels in London include  old Underground tunnels and horse tunnels.Surely, if these were converted to cycle routes it would provide a clean, warm , dry and safe environment for cyclists as well as keeping roads clear for traffic?
The ventilated air in the tunnels could be filtered so cyclists would be breathing clean air as opposed to the toxic pollution in the streets above.
The number of cyclists killed or seriously injured would be significantly reduced.
It would surely make cycling to work or a meeting more attractive if it can be done in a dry, warm environment with clean air to breathe and no dangers from traffic?
There is also the disused Mail Rail which is currently being considered as a tourist attraction project. It begs the question why isn’t the Mail Rail used for Mail if it could take Royal Mail vehicles off London streets? If it is no being used for mail then this could also be used for cycle routes.
TFL, who owns 750 of the tunnels, is said to be in talks over whether it should invite construction firms to bid for a single site to begin the project (using the space for business ventures), or for a group of the vacant subterranean spaces.
Tube stations have been closed for a variety of reasons over the years, ranging from low passenger numbers to re-routing. One of the most famous locations is Aldwych, which was used to hide the National Gallery’s collection during the First World War and then British Museum artefacts during the Second World War.
The rejuvenation idea was first proposed in 2009 by former banker Ajit Chambers, who estimates that an untapped £3.6bn is harboured by the network.
Chambers came up with the idea after finding a map detailing the 26 “ghost stations” concealed within the Tube network. He identified several that could potentially be transformed and formed start-up The Old London Underground Company.
Surely the idea of using tunnels to create safe cycling routes would be better than trying to create yet another business opportunity?