Crank bolts - Allen key or hexagon?

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Crank bolts - Allen key or hexagon?

Postby JS » 14 Oct 2004, 3:43pm

This is hardly the most important issue around, but I was idly musing over it...

My older bikes all had crank bolts with hexagon bolt heads. The crank extractor had a socket spanner for use on these bolts with the aid of an adjustable spanner - all fine and dandy.

The two more recent (ie in the last ten years) bikes I've bought have both had socket-head crank bolts needing an 8 mm Allen key. When I go on tour I still have to take the crank extractor and I still take the adjustable spanner. But I now have to take an 8 mm Allen key as well which doesn't do anything else useful on the bike that I've discovered yet.

Is there any advantage in socket heads for crank bolts? Is there any reason not to change back to hexagon heads and save the weight (admittedly small but it's the principle that counts!) of the Allen key?


Re:Crank bolts - Allen key or hexagon?

Postby CJ » 15 Oct 2004, 10:29am

Sure you can swap those allen-key bolts for hex-headed - if you have any spare - and you'll also want some dustcaps to stop the extractor threads getting full of crud. (I expect your allen-key bolts have captive plastic washers that protect those threads.)

A better notion is to swap those allen bolts for self-extracting allen bolts, that come with a special kind of dustcap and thrust-washer combined. So when you unscrew the bolt it pushes the crank off. Then you can leave the extractor tool at home and save much more weight. Some of these (I think the TA ones) work with a 6mm rather than an 8mm allen key, and although you need an extra-long, extra-strong 6mm allen key, at least it fits a load of other stuff on the bike.


Re:Crank bolts - Allen key or hexagon?

Postby JS » 15 Oct 2004, 12:12pm

Thanks, Chris. I had no idea you could get self-extracting crank bolts, sounds like the best solution because as you say I resent the weight of the crank extractor. But remembering how hard you sometimes have to lean on the spanner to loosen the cranks, that strengthened 6 mm allen key had better be jolly strong!

Your input to the latest Cycle must have been the lowest ever - not only did you not do the main cycle review, you didn't get to do any of the product reviews. It's been obvious that your input has been lessening since CTC outsourced the magazine production - I very much hope there's not a campaign to eliminate you altogether!

(instead of posting a "bikes and bits" question on another board, I'm overcompensating by posting this here...)


Re:Crank bolts - Allen key or hexagon?

Postby Wrongside » 19 Oct 2004, 10:04pm

JS, I'm curious why you would bring these along in the first place? Are you going to Mongolia? :-)

In the 1970s, I used to tour with a crank extractor, socket to turn it, cone wrenches, Campag pedal wrench, etc., etc., etc. After all, you never know when a bearing might seize up! Even then, I was never willing to lug around a pair of headset spanners.

But they never did. And if you check your chainring bolts before you leave home, why would you ever have to pull a crank off on tour? After all, these days "servicing" a BB consists of replacing it, so you'll need a bike shop anyway. If a crank needs tightening up, find a garage, DIY, LBS etc. and borrow or buy the Allen key there.

In any case, I think there are a few things that are best left to a forced detour in search of a bike shop or garage should the remote need ever arise. Replace the weight with a small flask of brandy which you'll use more and enjoy more.

As for the adjustable spanner: I'm curious, what's left on your bike that still needs it? You might need to pull the cassette to replace a broken drive-side spoke, but a fibre-fix kevlar spoke will tide you over. In fact, having replaced the Suntour XC Cantis on my Thorn with Oryxs, the only hex bolts left are the clampbolts on the mudguard stays.


Re:Crank bolts - Allen key or hexagon?

Postby CJ » 20 Oct 2004, 9:00am

I once had to regrease a bottom-bracket at the roadside (water had got in after crossing an alpine pass in deep snow and I couldn't stand the banging noise any longer). Thanks to having the tools to hand it took only 30 minutes, so much less hassle than trying to find a bike shop.

We've been there too: tedious diversions to scruffy towns we never intended to visit, time-wasting delays for shops to open from 3 hour lunch breaks (this isn't Mongolia, just Portugal) only to find they don't have the part anyway.

Bottom-brackets are better sealed nowadays, but I've nevertheless been glad to have the means of pulling a crank several times recently: to extract badly jammed chains from behind the little ring. Never on my bike and usually mtb rides, but it beats hanging around for ages in the cold while someone tries to fiddle it out some other way.

Self-sufficiency rules okay?


Re:Crank bolts - Allen key or hexagon?

Postby JS » 21 Oct 2004, 1:43pm

Hi Wrongside

Actually I'd been wondering myself whether I really needed some of the tools I carry. Perhaps, as Chris has diplomatically declined to rise to the bait of whether CTC are squeezing him out of the magazine, we'll have to debate tool kits instead.

My habits were set as a student, when, as students are, I was short of money, but also when I didn't realise what a false economy buying the cheapest replacement parts possible was. Thus I went off on tours with a grotty bike prone to frequent mechanical problems, and each time a new thing went wrong I tended to add the necessary tool to the toolkit next time. Specifically, I kept fitting cheap bottom brackets which were forever getting pitted or otherwise needing adjustment. Ten years ago, with the benefit of a paypacket, I was persuaded by Pearsons to buy a sealed BB, which since then has not needed a single adjustment. So I tend to agree a crank remover is probably not necessary, but it's the better safe than sorry mentality. And if a crank did work loose, I'd rather tigten it on the spot than ride on it to the LBS.

As for an adjustable spanner, the main reason was for the crank removing/tightening, and wheel removal - hub gears don't have QR!Also emergency tightening of hub/pedal cones. But I still have a surprising number of hexagon nuts left despite changing all the bolts to allen sockets: the upper fixings of both front and rear carriers, front brake bolt now holding dynamo front light, hub brake reaction arm, mudguard, seat pillar clamp on one bike, control cable clamp screws.

Another thought: even in NW Scotland, never mind Portugal, finding a LBS could take half a day. It's a balance between security and weight, isn't it: like you, there are things that I've never taken the wherewithall to adjust, whereas I once met someone who claimed to have toured in Asia without even a puncture kit - he said a flat tyre was a great ice breaker in local villages.