I don't believe there's a specific 'number of pics' limit per se, but there is a size limit for individual pics and so for individual posts in a thread, so if you have too much text or too many pics/pics that are too large, you'll possibly have problems posting it up..... and on top of that, for a variety of reasons your connection might be dropping out before the whole lot is loaded, so you get nothing; or it could be timing out because it's taking too long to transfer all the pics over, so you'll get nothing; and there's other device, software, or connection issues that can do the same sorta thing at the loading end.... :gaah:
However, that said about there being no specific listed restriction on the number of pics loaded per post, please remember than not all users will be reading your post on a desktop or pc with an unlimited capacity or bandwidth connection, so as Isopedella suggested,
please try to limit the number of pics for each individual post to around Five (5) or Six (6) max for each individual post in a thread - if you have more pics than that to show,
simply add another post or 6 or even 60 to the thread! 
hyea:
By doing this, you'll be breaking what would otherwise might be a potentially problematic
massive post up into smaller chapters & making it less likely that you'll lose or be unable to post the whole lot as you mentioned above; besides giving you an opportunity to look at & check each post with maybe 5/6 posts as you post them up! It'll also mean that anyone who's on the other end of those problems mentioned above can read your posts & ride reports, instead of maybe locking some potential readers from the thread entirely, and
EVERYONE who tries to open your Ride Report will be able to do that, even those reading on small capacity &/or small screen devices as well as those who have restrictions or limitations on the capacity or download speed of their connection. :thumbup:
You'll still be able to tell the same story, only you'll do it by effectively taking a breath or two between each post containing 5 or 6 pics in it before moving on to the next post in the thread; making it safer/easier to post, check,
AND ALSO to read, by giving your potential readers the opportunity for a breath or two between each post in the thread as they work their way along as well.

Thanks :cheers: