Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2023	May 01, 2023
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2023
Document Transition Report	false
Entity File Number	001-38916
Entity Registrant Name	Bicycle Therapeutics plc
Entity Incorporation, State or Country Code	X0
Entity Tax Identification Number	00-0000000
Entity Address, Address Line One	Blocks A & B, Portway Building, Granta Park
Entity Address, City or Town	Great Abington, Cambridge,
Entity Address, Country	GB
Entity Address, Postal Zip Code	CB21 6GS
City Area Code	+44
Local Phone Number	1223 261503
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		30,043,486
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001761612
Amendment Flag	false
Ordinary Shares
Document Information [Line Items]
Title of 12(b) Security	Ordinary shares, nominal value £0.01 per share*
No Trading Symbol Flag	true
Security Exchange Name	NASDAQ
American Depositary Shares
Document Information [Line Items]
Title of 12(b) Security	American Depositary Shares, each representing one ordinary share, nominal value £0.01 per share
Trading Symbol	BCYC
Security Exchange Name	NASDAQ