Do I really need to change my front crank?
I have an '05 Trek 520 with the standard Shimano 105 crankset (52/42/30). I have loaded up my rear panniers with bricks to 50lbs (23kg) and road a bunch of hills on a 20 mile ride. I didn't seem to have an problem on the hills, and when I did, I stood up to pump.
I guess I am wondering, how do I know if I should swap out to a lower gearing? Should I do a fully loaded extra long ride (60mi?) and see how exhausted I am? Since I have no touring experience (at all), isn't it a bit premature to make changes to the mechanics of the bike that might actually be just right as it is [for me]?
Any one have advice on how to know when to change your crank?
The fact you had to stand up and pump indicates you need lower gearing. That is exactly what the granny gears are for. Look I could use the 52 part on my touring bike, assuming a sufficient downhill, the real issue is whether you have a low enough range, and I suppose, have the graduations in the real range you will use.
Of course how hard you work is ultimately up to you, and also involves your sprocket.
You don't have to change your whole crank, just the chainrings to a lower set, if that is what you want. Train with what you have (Loaded) and decide for yourself. In my opinion you should have low enough gears to easily spin your way over the steepest hill you expect to encounter. Also remember while on tour you might meet that hill with a headwind or when you are really tired from many days in a row of cycling. That is just my side, I know that I'm a slow tourist and there are plenty of folks out there that want more speed in the upper end and don't mind pushing a bike on the rare occation.
You won't be able to cyle fully loaded day after day if you are needing to stand up and pump on every significant hill. Either change the rings or change the cassette to one with a 32 or 34 bigget sprocket.
Thanks for the advice,
I was wondering, do you really need an mountain-bike like spread of gearing (e.g. 42/32/22), or is there a benefit to having a 'road' gears for the large and medium, and a really small 'mountain' gear for the tough hills? Something like 52/40/20 on the front, with a normal range in the back (11-34).
What do you think? I was thinking you would use the '20' on the hills, but as soon as you hit something that is manageble make the leap to the '40'.
I'd like peoples opinion if this sort of jump in gearing would be detrimental for people on fully-loaded tourers through some hill-country?
I ride my bike
a 20 seems like overkill to me.. youd be going so slowly that balance might be an issue : ) and a 20-40 leap seems a bit drastic as well. I rolled with 28/38/48. it kept my shifting pretty smooth and I only wished for more (less?) ratio once or twice..
24 up fro with a 34 in the rear should be plenty.
This question is very similar to a thread from a few days ago. I have attached my reply to that post below and will repeat my recommendation, especially if you think you will be encountering significant mountain passes. Even with the 20 chainring, I struggled on some inclines (I was 46 years old at the time and in excellent shape). Contrary to another response, a 20 chainring does not mean you will have balance problems but you will be able to go up almost any hill, (I say almost but in my case I was never beaten) and I tackled significant inclines both loaded (25-35Kg) and unloaded.
As I have previously stated on these forums, I don't really tour at this time but hope to get back onto the long distance roads in the next year or two. However, when I was touring in the mid 90's for about six years of rather intense (my friends would say obsessed!) riding, a 1994 Cannondale T700 was essentailly the only bike I rode. The gearing that I had on this bike, after some tweaking) was:
44/34/20 chainrings and a 11-28 cassette.
It was great for touring in the mountains of BC, Alberta, Montana, Idaho and Washington. I'm sure the low gearing (.71 ratio) helped keep me injury free during that time period. And on the other end, I did a lot of no-load training on that bicycle including a few 200 and 300km brevets. The high end was fine for my style of riding which is by no means timid.
My recommendation - use the lowest, low gearing possible for touring.
A low granny isn't overkill IMO. I like a nice low on my tourer, and do without the high end.
For my next tour I'll also be dropping the small sprockets from my cassette, in favor of a Harris Cyclery custom cassette. This will give me a better range of usefull gears for my style of riding.
52/40/20 might be possible, but doubtfull. If it is possible, there would be problems to be warry of. Front shifting will be sloppy overall, and moreso going granny to middle and back. New deraileurs may be required, surely a long cage rear. Crosschaining when in the granny could possibly destroy the front deraileur-as opposed to just the normal shortened drivetrain wear.
I've 52/42/26 on my brevet bike, and have the noted above problems, which I'm warry of.
Not knowing the OP's skill, riding style or experience. I wouldn't recommend it for loaded riding, just on the basis that the question was asked (not intending to offend).
"Grinding" up the occassional hill while unloaded might be fine on occasion. However this can lead to injury (achilles/knee) a lot faster with a load than without.