Everyone on the trip was supplied with the same bike a Raleigh Global 2000 (designed especially for this trip). They feature the Shimano STI shifters and 105 gear set with 27 speeds (gear numbers 32..107). We are contemplating modifying our cassette and crank set to get a couple of lower gears. We have 700C x 28 tires with presta valved tubes. I think the tire size will be just about ideal for most of this trip.

We went ahead and changed our rear cassette the the Ultegra 6500 and change the small front sprocket down to 28 teeth. This gives a range of 28 ..116, which I know we will appreciate when we get to the Andes. Here's our current gear chart:

Ours	Front Sprocket
Rear Cog	52	42	28
12	116	94	63
13	107	87	58
14	100	80	54
15	93	75	50
17	82	66	44
19	73	59	39
21	66	54	36
24	58	47	31
27	52	42	28

Original	Front Sprocket
Rear Cog	52	42	30
13	107	87	62
14	100	80	57
15	93	75	54
16	87	70	50
17	82	66	47
19	73	59	42
21	66	54	38
23	61	49	35
25	56	45	32