Shimano 105 Groupset options


New Member
New here and to biking as well so please forgive any blatant idiocy

I purchased a beat up 2012 or 2013 Specialized Allez a few months back and unfortunately, the gears are beginning to slip and are difficult to change, also my brakes are rusted. Since I bought the bike fairly cheap I wouldn't mind doing an upgrade and replacing the entire groupset.

I'm looking at the Shimano 105 groupset from the site below, the only issue is that I haven't got a clue what the different options mean. This is a 54 cm 10 speed bike, what would I need from the options to make this work? is there another site I should buy from? any help would be greatly appreciated, thanks!


34/50, 36/52 or 39/53 are the number of teeth on the chain set (most people opt for the 34/50 version - known as a compact) while the 165mm, 170mm, 172.5mm and 175mm are the crank lengths. This is all a matter of personal choice, but I'd guess a 170 or 172.5mm would be best suited to you if you ride a 54cm (medium?) size
105 Groupsets

5700 - 10 speed (this probably what you currently have installed.

5800 - 11 speed which can take up to 32 tooth rear sprocket dependent upon having the medium cage rear derailleur fitted.

R7000 - 11 speed which can take up to 34 tooth rear sprocket.

If you’re going to upgrade to 11 speed you’ll need to upgrade the shifters also (which are included in the groupset you link to). You will also need to check whether your rear hub will accept an 11 speed cassette as they are slightly wider than a 10 speed. If it currently has a spacer fitted behind the cassette, then you can fit an 11 speed cassette if you remove the spacer.

If not, then you are limited to 10 speed unless you change/upgrade the rear wheel. In that case, the newer Tiagra groupset would be a good option.
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