corynardin

I have a full Shimano Deore drive train that I would like to use for a cyclocross bike with a pair of Tiagra STIs. I am pretty sure that they are both 9 speed. Will there be any compatibility issues that I need to deal with. I seem to remember reading something on Sheldon Browns website about Shimano using different spacing (and thus different cable pull) for there mountain and road components.

I am still new to working on bikes so I don't know all of the ins and outs but hope to learn as I go. Also, is there one book that is worth investing in or is YouTube really the way to go?

Cynikal 

If they are both for 9 speed then you should be fine.

telebianchi

I use a Deore LX rear with 105 9-speed brifter. Works fine. One thing to check is which way the derailer moves when the cable is pulled. My rear derailer works opposite of a standard road derailer. Therefore, to shift to the bigger cogs I now have to click the inside lever and to shift to the smaller cogs I use the full brake lever. I didn't plan for this, but for a CX race or when using the bike on mountain bike trails I actually prefer this shift pattern since I tend to want a quicker shift to the lower gearing. Only issue is switching back and forth between the CX bike and road bike; I'll sometimes shift the wrong way if I haven't been riding one of them in a while.

corynardin

It appears that the derailleur does pull the opposite way. Is it possible to run a rear long cage road derailleur with my MTB cassette and double chain ring?

Andy_K 

The incompatibility is with the front derailleur. If you're running a double, that's not an issue. The rapid demise derailleur orientation isn't an issue except that you need to think backward about your shifting.

A mid-cage road derailleur (long cage by road standards) works with a 30T cassette and you might be able to get away with 32T. I had one setup that way but the derailleur bounced a little when I was on the big cog. Other people have reported having no trouble.

corynardin

I have seen a few road cassettes that go up to 28 teeth and some MTB cassettes that go down to as few as 32 teeth, but I haven't noticed any that are 30. Do you know of any?

Andy_K 

The new Tiagra 4600 10-speed cassette comes in a 12-30 variation.

See my review here: https://www.bikeforums.net/showthread...speed-cassette

Andy_K 

BTW, if you are talking about CX racing, as opposed to just riding off road with your CX bike, I don't know if 12-30 is the way to go. In my experience, the chain seems to find its way onto the lowest gear I have and if I don't limit how low that is while I'm not in the pain cave I find myself dropping off the back in a hurry. There are a very few cases where I like to have a super low gear but in general it tends to work against me.