Spamming isn't the issue
I'd
personally prefer the limit higher. but also see a lot of vastly less experienced/skilled/safe bicycle riders on our roads, especially in the city who I think 15mph assistance would be more than enough for.
I just don't see that you've put a very well thought out compelling case across in the petition.
ie. What has the US legislation to do with us at all? (did you even realise the US have many restrictions on where bikes and Emtbs can be ridden that we don't)
and where on earth did you get this from?
?
or
again? where is your actual evidence of this?
and
What? How on earth can you say your proposed assistance increase would
prevent "much faster bikes"?
I just think you should have spent a lot more time time actually researching the subject and a lot more time coming up with better reasoning preferably with some actual proof behind your claims and written it more betterly.

As it stands even if it ever does get to parlaiment, some old dude who knows nothing about bikes is going to read out your badly thought out proposition and the rest of the house who live in london and probably see cyclists as a red light jumping nuisance will vote to say... No.