Every rider should have at least a decent multi tool. I’m sure your local bike shop has a vast selection of multi tools that come in different shapes and sizes, and that contain a variety of different tools. A very inexpensive multi tool might have a couple hex wrenches. A super expensive multi tool might have 30 or more tools on it. In my opinion, you probably want to buy the multi tool that is the most compact that also contains every tool you might need. A multi tool with 30 different tools will probably be too bulky for your saddlebag.
I’ve had about a half dozen different multi tools. It’s enough to I know what I want out of a multi tool, but I’m by no means claiming to be an expert about all tools.
When I travel for races, I usually pack pretty light; especially when carpooling. Rather than taking a big toolbox, I’d rather just be able to pull any tool I need out of my saddlebag. When you’re at a race, you need to be prepared for just about anything. We race in some pretty remote areas. It’s not like there’s a bike shop on every corner in Eucha, Oklahoma or Mineral Wells, TX. Simply carrying a tool with 5 or 6 allen wrenches might not cut it.
I don’t think we all need a behemoth multi tool (like the Park Tool Premium Multi Tool) with 30+ gadgets, but it’s nice to have something with an array of hex/allen wrenches, torx wrenches, spoke wrenches, and a chain tool. I have two multi tools that meet these expectations. One is a Crank Brothers M17 (17 tools in one). The other is a Lezyne Rap 14 (14 tools in one). I can easily fit either one in a very small saddle bag with a tube, CO2, inflator, tire boot, and a couple dollars. Both tools are high quality items, but I have some minor complaints about each.
Here’s what you get with the Crank Brothers:
chain tool: 8/9/10 speed compatible
spoke wrench: #0, 1, 2, 3
hex wrenches: #2, 2.5, 3, 4, 5, 6, 8
screwdrivers: phillips #2, flat #2
open wrench: 8mm, 10mm
It has a big brother (M19) but you only get an extra phillips and extra torx. I guess if you have a bike that has some t-10 torx bolts, the M19 is worth it. Otherwise, I would take whichever is in stock. I don’t think the m19 is any bulkier.
If you take the chain tool apart, you have access to the 8mm and 10mm open ended wrenches. For the first couple years I had this tool, I didn’t even realize these little cutouts were wrenches. They aren’t super useful because they are so small, but it’s enough to grip a nut as you unscrew hex bolt with the rest of the tool. It could come in handy. The part of the chain tool you took off also has 4 spoke wrenches. These work pretty well and fit a wide variety of spokes. My ONLY complaint about this tool is that the pin in the chain tool should be a little longer. Mine is about 5 years old, so it wouldn’t surprise me if they fixed this by now. When I break the chain with mine and thread in the entire chain tool, I get to the end of the threads before the chain actually breaks. I have to extract the chain tool and bend the chain backwards with my hand to actually break it.
The Lezyne is pretty similar. Like all Lezyne stuff (including their mini pump), it's pretty nice looking. Here’s what you get with the Rap 14:
Hex 2, 3, 4, 5, 6, 8mm
Chain Breaker: (9/10/11 speed)
Star Shaped T25, T30;
Spoke Wrenches: Mavic Mtv, 3.22, 3.45
You get one less hex (no 2.5) but an extra torx (star). It has tools for 3 different spoke sizes, including the big mavic spokes. I find that the chain break works better on this tool than the crank brothers because the pin is longer. It lacks a 8mm and 10mm open ended wrench, but it’s not a big deal breaker for me. My one complaint about this tool is that the 2mm hex is an L-shape rather than straight. This is a pain when you are changing your brake pad cartridges out. All of the lezyne multi tools have it this way. It doesn’t make sense to me. Other than that, this is a perfect tool. It’s compact, has everything you need, and very little that you don’t need in a multi tool. Other than cable cutters and a pedal wrench, this tool has every tool you need for 90% of the bike maintenance you’d have to do at a race or on the side of the road.
Now that I’m looking at both tools, I think I can actually interchange some of the pieces between the two. I think I can take the stupid L-shaped 2mm hex off the lezyne and replace it with the much better 2mm from the crank brothers. I think that pretty much makes the perfect multi tool for my needs. If the latest version of the Crank Brothers M17 has a better chain tool than my old one, I would say that's the perfect tool for most riders.