Bicycle Mechanics - What wrench to buy for my seat bolt?

My seat bolt is similar to the one in the picture attached. The top of the nut (left end in the picture) is not plain flat surface, but has a something like a hexagon "hole" or concaved-in center (there must be a term for that, but I'm total layman). I am not sure if I should buy this wrench (http://www.amazon.com/gp/product/B000NPR22Q/ref=ox_sc_act_title_2?ie=UTF8&smid=ATVPDKIKX0DER) or this one (http://www.amazon.com/Black-Decker-RRW100-Ratcheting-ReadyWrench/dp/B0042AM7E6/ref=lh_ni_t). Or does it matter?

If it has a hole for an allen key, then buy an allen key set.

An allen key is to use for the "hole", but what about the outer side of the nut? Should the wrench have both aspects or either one of them?

An allen key is to use for the "hole", but what about the outer side of the nut? Should the wrench have both aspects or either one of them?
One or the other. If you end up getting a box-end or ratchet type wrench set, make sure to get a metric set. Also if you get an allen set, make sure they are metric too.

Thanks. Glad I asked, because I already have allen key wrench. Just tried, it works.

I would get neither of those wrenches you linked to. The first set, the ratcheting wrenches, have heads that are oversize (for any particular given size). This means it can potentially interfere with the seat stays. They are also straight wrenches. A common combination wrench has a box end that is usually tilted slightly.

The second wrench you linked is a wide range "universal" wrench. It will suffer the same issues as the ratcheting wrenches, only likely worse.

Either one may work fine for you on your particular bike. The first set I consider to be an extra item in a mechanics tool kit, something that would be purchased later if you had a particular job that they helped in. The second wench I'd avoid anyway, they are usually gimmicky and have clearance issues. All the demonstrations you see are for best case scenarios.

I like to use an offset box end wrench for those style. A socket and ratchet would be fine too. Or the box end of a combination wrench. If you need a wrench on both the head and the nut, you'll need two wrenches or wrench/socket combos. I still like to have a nice adjustable wrench also, it can hold one side stationary. I've got all of the above, and if I need two wrenches, I'd use the offset box end and the box end of a combination wrench.

Edit: I was composing when you replied. If it is a recessed hex, then yes, you use an allen wrench. Most bikes are metric, so you'll want to look at that. Also, the nut is often keyed to the collar, the drive side is usually the bolt that turns. (sitting on the bike, the right side).

Good to hear you figured it out most most seat clambs take a 6mm allen or or 14mm open end so if you have even the most basic of tools your fine.

Are you talking about something like this?268372If so you need a allen key for one side and a hex head wrench for the nut on the other side..the hex head "nut" around the recessed hex is just for show.

Just get an 8 inch crescent wrench. It will take care of the nut, and you have the hex key for the bolt head. I have a couple of pounds of tools that usually go with me, and the 8 inch crescent often comes in handy.

+1 On the 8 inch crescent when working at the local bike coop my high quilty 8inch is what I use about 80% of the time.

Are you talking about something like this?268372If so you need a allen key for one side and a hex head wrench for the nut on the other side..the hex head "nut" around the recessed hex is just for show.

Thanks all for the helpful replies! Thanks for the pic: it is just like that! I am glad I do have hex wrench and a newly bought crescent wrench. Exactly a year ago when I was using quick release bolt it somehow loosened and the seat suddenly fell while riding (I posted a thread on that a year ago). Since then I replaced it with this dead bolt. Now I just need to raise the seat a little without having to go to LBS.

Thanks again everyone for the help!

Two of these, appropriate size of course, will do:

268377

Use the right tool for every job.

The 8 inch crescent is one of the more used tools for me too. I don't like quick release, so even my wheels have nuts. I've even used it to undo 8 or 9 millimeter machine screws when I didn't have a wrench that size.

Quick release is just thief bait, without a trap. Besides that, I had 3 quick release axles break within about 6 months. They aren't nearly as strong.

Two of these, appropriate size of course, will do:

268377Actually just one and an allen key, the hex nut looking end on the allen key side is just for looks and just spins like a washer..

The 8 inch crescent is one of the more used tools for me too. I don't like quick release, so even my wheels have nuts. I've even used it to undo 8 or 9 millimeter machine screws when I didn't have a wrench that size.

Quick release is just thief bait, without a trap. Besides that, I had 3 quick release axles break within about 6 months. They aren't nearly as strong.

Fail...

Use the right tool for every job.

I wish the guy that worked on my truck the last time lived by that motto. I think he only had four tools:
1: A hammer
2: A bigger hammer
3: Regular vice grips
4: Mini needle vice grips (tight places)

I wish the guy that worked on my truck the last time lived by that motto. I think he only had four tools:
1: A hammer
2: A bigger hammer
3: Regular vice grips
4: Mini needle vice grips (tight places)
He only lacked a chisel to cover all possible jobs.

+1 On the 8 inch crescent when working at the local bike coop my high quilty 8inch is what I use about 80% of the time.

Just make sure you get a metric cresent wrench ;)

I have a few different sized adjustable wrenches and use them at times, but for most work I prefer job specific wrenches. A mid-grade set of combination wrenches from 8mm - 18mm, a set of metric hex keys and a few carefully chosen sizes and lengths of both straight and phillips bladed screwdrivers will take care of a wide range of maintenance tasks without breaking the piggy bank.