miRNA. Reads to long or to short

Question

[ju_ra]

Hi guys. At the moment I am analysing a miRNA Dataset (QIAseq ® miRNA UDI Library Kit) of EVs. After trimming of the Adaptor and UMI etc. I end up with one sample group with a clear peak of average reads at approx 30 bp and another sample group with a buch of reads at 12-16 bp. Is this to be expected? I was assuming at should peak at 20? Any advice?

[biofalconch]

I think more info is needed for anyone to provide help: What software did you use to remove the adapters for example. I think 12-16 are way too short and you might have had over trimmed your sequences.