Well, you've brought up the subject of many a recent angry conversation. 

On the dirt side it's even worse as the BRP bisects thousands of miles of trail and creates  a "green wall" preventing bicycle access on trails on gravel roads that are on FS land but the NPS owns the 200-400' as the routes cross the Parkway.  Any hope we had of negotiating crossings at key locations are up in smoke for the next decade or longer.  

After meeting the Park Superintendent as a previous meeting about similarly anti-bike trail plan near Roanoke and skimming the reviews of the management plan I've avoided involvement as it looks so bad from the dirt perspective.  The Superintendent is  no fan of bikes and seems to feel that bike traffic both on pavement or dirt is detrimental to the NPS mission on the BRP.   Our southern regional director and legal pitbull are preparing comments, but IMBA is unlikely to put much effort into this beyond strongly worded comments  as this is not stacked in our favor.  First rule of success with NPS is having superintendent support.  With it you can walk though walls of paper and anything is possible, without those paper walls are impenetrable unless you wield a legal bludgeon and then you'll be sabotaged with unwilling compliance.    

However, that doesn't mean the road cycling community won't make a huge push and they should be supported.   This version of the management plan will likely outlive the current pigheaded superintendent and it would be nice to have a better plan for his successor to adopt. 

Please submit comments that illustrate the value of bicycling and push the local economies alternative (C).   With NPS plan comments it important to remember that you aren't voting, but rather providing thoughtful criticism and suggestions for improvement.  One well written letter with strong arguments and supporting documents can outweigh hundreds of " your stupid, don't do this" letters or form letters.   Remember your letters will be documents of public record and thus usable in appeals or as documented support for pro-bicycle actions(legislation) in the future.  With the new USFS planning websites it's possible to review everyones comments online shortly after they are submitted.  Not sure if the NPS is at that level of digital transparency in the their planning process.  

You can also recommend they scrap all three alternatives and come up with a fourth that encourages bike use.   This is a longshot, but a entirely new alternative is not uncommon when the public overwhelmingly rejects the "preferred alternative"