Is it a bad idea to agitate beer a few days after bottling?

Question

I just bottled a porter which had been in the fermenter for almost a month. I allowed myself a taste un-carbonated, and while I don't want to count my chickens before they've hatched, I'm very excited for this one.

On Tuesday, I'm going to be taking a 2-3 hour motorcycle ride to meet up with my sisters for Thanksgiving. I would love to bring a couple of bottles with me. I anticipate they should be ready for a first taste around the end of my stay, and if I think they need more time to improve I would leave them behind to be enjoyed in a few weeks.

The question is, do I risk doing any harm by carrying them for a couple of hours in my saddlebags? The suspension on my bike is not fantastic, so I am sure that they will be thoroughly shaken throughout the ride. By this point, the beer will have been bottled for about 2.5 days.

The only discussion I have seen of agitating beer during bottle conditioning is this question. There, everyone seems to suggest that the OP doesn't need to shake their bottles, but it's not clear whether its just unnecessary or actually harmful.

Edit in response to Henry Talyor's answer below: The beer is in big glass bottles with ample head space. Yeast is white labs liquid Australian Ale, harvested from a previous batch. Estimated ABV is just over 5%. So, pretty much average all around.

I'll note also that I've travelled on my motorcycle with (finished) beer before and never had an issue beyond bottles foaming over if not left to sit. So, my concern is not so much that I'll break the bottles as that I'll disrupt the yeast's work by shaking too much.

Answer 1

A little shaking is no problem at all, as others have mentioned it might even help the process along. At 2.5 days after bottling the yeast should be active, cloudy, and maybe even making a bit of foam on their own. There probably won't even be yeast on the bottom of the bottle yet, so you can handle them quite casually. The thing to watch out for are big temperature changes - either up or down. The yeast are working on a small amount of sugar (at the same time removing a bit of oxygen) and will likely take a couple weeks to complete anyway. Any quick cooling is likely to send them back to sleep which will delay carbonation and maybe allow oxygen to damage the beer. Warming is risky too - even if the yeast like the temperature, you'll have to cool slowly later to prevent the same problem above.

Answer 2

I'm assuming glass bottles with appropriate head-room and that your porter has an average alcohol pretty near the maximum tolerance of the yeast you used. If those assumptions are reasonable and if you've used an appropriate amount of priming sugar, then you are probably okay at 2.5 days.

The risks are two-fold, vibration and heat. I would suggest that you minimize both by packing your bottles in crushed ice. The loose packing with absorb some of the vibration and the cold may reduce internal pressure withing the bottles (I am not sure about this because both the glass and the beer will condense in the cold).
The negative side to my crushed ice idea is that it will probably slow down the carbonation process, so you may be drinking flat beer with your sisters. Given that down side, I would suggest bringing twice as many bottles as you need, chill half and pad the others. If you are lucky, none will explode and you will have extra beer for the end of your holiday. ...and worst case, you can leave the cold ones with them for later sampling.