true its not a true timing chain. the bike has a performance motor with the 2.5 to 1 gear so it has I think a 18t chain ring the back I think is 48 can't remember for sure since it was rebuilt. if we get the new motor it has a standard size chain ring and it wont freewheel so the cranks are locked together like they should be. the bike does have a normal tandem bottom bracket that I had no clue about the first time I had to deal with the timing chain. the bosch cx motor is the cargo/mountain bike motor so it will come with several different sizes of chain ring. we cost when the bike goes faster then 23mph. but we climb a lot of hills. Saturday we did 2500 feet in 15 or so miles with most of it at 10% or more grade. so climbing is the most important we cruise at 18.5 right at the motor cutoff. I think right now its 46 and 11-34