The London Cycling Campaign has an online facility for people to write to the London Mayoral candidates about the importance of cycling. You can use the boilerplate text as is, or amend/add to it.
I added "4. More 20mph limits" as I know some candidates have vowed to reduce/abolish them (probably while also calling for safer streets).
londonlovescycling.org
Kind regards
Colin Newman ¦ +44 7761 577255
Barking & Dagenham Independent Cycling Campaign
stibasa.org.uk ¦ facebook.com/barkinganddagenhamindependentcyclingcampaign
In LB Barking & Dagenham:
Former local branch Leader for London Cycling Campaign lcc.org.uk
Cycling UK Campaigner cyclinguk.org
Campaign Leader for 20splentyforus.org.uk and
Active Travel Champion for sustrans.org.uk
Cycling events in NE Greater London meetup.com/hubbub