Yeah I thought as much. The 4600 does have a longer cage derailleur, but seeing as there was nothing bigger than a 30T, I don’t know for sure if the 4600 long cage derailleur would fit up to a 34T. the 4600 cannot use the 4700 rear derailleur unless you change the shifter as well, so that’s not an option.
By all means go ask the shop for the 34, but you will definitely need new chains and rear derailleur, and probably new shifters as well.
Looks like a 32 can be done ok.
But he already has a 32 and wants a 34… right?
He has a 30. Liub is probably right though, 30 should be enough.
Oh, OK.
Thanks everyone for the input. The thing I really like about my present gearing is that it really is an all-around, good gearing for various circumstances. For example, on the flats, I almost never have to use the highest gear, and when I do (slight downhill or wind at my back or perfectly flat conditions with no wind), I don’t feel like I get to a high enough speed to where I’m just spinning (40kph and higher easily with no spinning feel). And the 30-34 is decent for the mountains.
But, on the other hand, I can definitely imagine how on Wuling, after 2500m of climbing with much more to go, I’ll be regretting the decision not to go for a 32 and I’ll be cursing all those in this thread that told me I didn’t need to make the switch. F*&^%$ bast&*$$ on forumosa, I can imagine myself saying.
Edit: But I wonder…if I were to change to a 32, would this necessarily change things for the highest two or three gears with the large cog at the front? Does changing to a 32 change everything around?
Highest gear nope, highest three gears will have a bigger jump in between. It’s still a 11T cassette.
Only advice is to change it ASAP to make sure everything runs fine 
and you’re used to the new gearing.
Okay, thanks. I’ll definitely look into this then. I’m thinking early summer of next year for Wuling so there’s not a huge hurry. I think more important now is to work on my endurance and hill climbing. Maybe two mountains instead of one more often now.
Try and do a double FGZ without blowing up, that’s a good target.
Double FGZ is too much downhill time.
Old three peaks is a pretty good gauge of endurance, lots of people use it for gauging their Puli to Wuling time.
Of course, I know you don’t plan in going full pace, but being able to finish training routes, no matter the speed is helpful for prepping.
marasan, dude, go for a 34.
I used a 34x34 climbing to Dayuling and still sucked wind the last 29k above Lishan.
When I got through the tunnel and looked at the clouds below on the East side. I felt weak in the knees and very pale (see pic below) LOL!
and, oh yeah, I descended the gorge in about 4 hrs and my brakes never overheated. I nearly froze! I got to the hostel about 1 k past the Arch of Taroko just after dark. I soaked in a hot bath for half an hour just to recover. That was Feb 16, 2015. Winter, I guess. Great trip!
There is some info here about my Hehuanshan trip in March 2017;
https://tw.forumosa.com/t/hehuanshan-trip-report/158999
A lot of good info here and in the post after yours. For all practical purposes, I’m new to cycling in the mountains, even though I’ve had my bike for almost four years.
I got it initially to compete in triathlons. After some practice, I wanted only to come in the top three or four or so for the bike leg, and I did end up doing just that with my crappy bike and some aero bars.
I now feel I need a new goal. I’m going about things by slowly increasing the distances and elevation. I think by the end of the year I’ll change my gearing around. You’re the second person recommending 34.
Edit: top three or four for my (old man’s) age group.
Sounds good, so don’t be shy, show us your bike. I showed you mine!
I would love to return and do this route without the pack I lugged up there last time. It would be wonderful to climb unencumbered.
A few days ago.
Our plan is to go with a van. The van will bring us to the starting point, meet us at certain points along the way, and then drive us back down. Reading about your experience, I’m convinced that being driven back down is the way to go.
Descending on the Taroko side would be great, but you would either;
A. Need to be fit enough to do the climb sufficiently fast enough to have time to descend in daylight
Or
B. Need to stay at the top and descend in the morning.
Also you need to be VERY wary of the steel drainage grates that punctuate the road.
I found that the road between Lishan and Dayuling had many small villages and places to seek refuge. The Taroko side has nothing, other than at a few key points.
I think you are wise to do it with a support vehicle, if for no other reason than not having to schlep a whole wardrobe up there with you. And you could stash a thermos of coffee or soup in the vehicle.
…and also be super careful of the many cracks that occur in the road surface, especially on corners. Blind hairpins with cracks just wider than your bicycle tires are a recipe for disaster, and made life very interesting when i came down that way (admittedly in summer, so not so cold).