It is really strange. Surlys come is lots of different sizes, but they are all the same size... I don´t actually ride a Surly, but min CX bike is inbetween the 46 cm and the 50 cm.
In the sizes that you probably are looking at, the main difference will be how many spacers you leave under the stem. If you pick a smal size and want a high stack, you will have lots of spacers under the stem (unless you by a compleate bike with the sterer cut to low...). If you by a larger bike and want a really low stack, then you need a strange stem.
It is really strange. Surlys come is lots of different sizes, but they are all the same size... I don´t actually ride a Surly, but min CX bike is inbetween the 46 cm and the 50 cm.
In the sizes that you probably are looking at, the main difference will be how many spacers you leave under the stem. If you pick a smal size and want a high stack, you will have lots of spacers under the stem (unless you by a compleate bike with the sterer cut to low...). If you by a larger bike and want a really low stack, then you need a strange stem.