I've messaged about 20 bike sellers and only about 5 have gotten back to me.

I usually make my message extremely short, consisting of one small sentence with a simple question such as:

What is the standover height of the bike (measured from the ground to the top of the top bar)? Thanx.

Almost always there is no reply.

I'm just wondering if it is just me this happens to? I'm starting to doubt myself here. To be sure, a 1/4 response ratio is quite low, considering that there is money in it for the seller.