So, about a week ago I decided to see if I could figure out how to take the crankset off my mountain bike (which never sees use except when my roommate uses it, which is rarely) and put it on my touring bike. Turns out that, yes, I could do so, but adjusting the front derailleur to make it work is currently beyond me, so I left it - it rides (and shifts) fine, I just can't shift down to the smallest chainring.

I haven't had time to get it working properly, a process which I think would involve swapping front derailleurs with the mountain bike as well.

Then today, sometime after one in the morning as I'm riding home from work, the left pedal felt weird. Kinda like it was twisting or wobbling at the top of every rotation. "weird", I thought, and decided to check it out once I got home. (It wasn't far at this point, maybe 2-3 kilometers, and I didn't have any tools on me) It gradually got worse, until the left crank arm fell off entirely, and I had to spend several minutes blindly sweeping my hands through the thankfully recently-mowed grass, trying to find the bolt.

Now, I don't know if it fell off because the crankset from my mountain bike is incompatible with my touring bike and can't be properly attached, or if I just failed to properly tighten it down, but if I had a toolkit on my bike I could (and would!) have stopped, found out what was wrong, and fixed it. On longer rides, I have tools in one of my bags, but I don't expect to need them on a quick trip to work.

For now though, I'm probably going to swap the cranksets back, since it's not actually doing anything to have them switched. I'll likely just take the road bike into my LBS along with the mountain bike crankset, look plaintively at someone and go "will this work?"

For the record, my touring bike is a Jamis Ventura Sport, and my mountain bike is a Schwinn....something? I'm not sure of the model. I inherited it, brand new, about four months ago, and I haven't used it much.

If your touring bike has road bike front cranks, the distance between the chainrings is not the same as on a mountain bike, this will explain why you cant shift properly.

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I can change between the large chainring and the medium one without issue, but the front derailleur that came with my road bike can't go low enough to shift to the small chainring. I tried to change derailleurs when I changed cranksets, but I can't without a chain tool, and I haven't (yet) had time to go get one.

Anyway, as per the subject line of my original post, I intend to get some sort of tool kit and mount it permanently on my road bike. Probably it'll just be a plastic tub in a water bottle bracket.

The issue with the crank is a little more serious now. You are unlikely to ever get it to stay on the BB spindle for any period. By keeping on pedalling with it loose, you've damaged the faces on it that allow it to mate properly up to the BB spindle.

Even if you wrench down on the securing bolt with a huge amount of torque, the crank will still move ever so slightly on the spindle, and because of the direction you pedal the crank on that side (counterclockwise), that movement will work on the bolt to loosen it.

The only long-term solution is to see if you can track down a replacement, unused crank of the same length and offset.

As to the chainset swap, it's likely that you need to swap over the BB cartridge with the MTB crankset to achieve the same chainline. Road and MTB spindle lengths and offsets are, I think, different because they also have different Q or tread factors.

Changing the derailleur to bring the MTB one on to the Jamis won't help if the Jamis has road shifters.

Is the Jamis originally equipped as a triple with triple shifters?

Rowan is probably right, but you can try to get the crankarm tight enough to see if it will work. If you were not pedaling hard, you might not have damaged it. It might have had a squeaking noise before it got really loose, that is another warning to be aware of. I have bought cranksets on ebay for under $30 shipped, watch for a replacement, but you would have to know what type of bottom bracket you want to put the crankset on.

Regarding your specific question, how to carry tools and you mentioned in the bottle cage - I have a plastic bottle that was sold for that purpose, fits perfectly in the cage and I carry tools, saddle rain cover, plastic bag (for under rain cover for redundancy), some plastic disposable gloves from my dentist's office to keep my hands clean when I do a repair, spare tube, tire levers, etc. I also have a nylon bag that was designed to fit in the cage and have used that too. Some peanut butter plastic jars will fit fine, as do some parmesan cheese plastic bottles. If you use a food jar, consider painting it first so people don't see your tools in the jar.

I aways pack my took kit pretty full and it is hard to dig out a small tool when I need it so I also carry a small multi-tool in my pocket on rides farther than a mile or so. The multi-tool I usually carry in the pocket does not have the 8mm bold most crankarms use, but it will work on everything else. The multi-tool in the took kit includes that 8mm bolt.

I have been working with tools for decades and rarely use a torque wrench, but the crankset bolt that holds the crank arm to the bottom bracket is the one bolt on a bike that I always use a torque wrench on. I had to buy the 1/2 inch drive 8mm allen tool for that specific bolt.

Crank arm bolts usually come with blue loctite, if yours did not you might want to buy some.

Doubt it. My touring bike has an Ultegra 10-speed road triple FD that shifts a Deore 9-speed MTB trekking crank just fine. The real problem is that MTB and road cranksets have different chain lines. When I installed the MTB crank on the trekking bike, I removed one of the BB spacers so that the MTB crank is a little bit closer to the frame than normal. That was all that was necessary to allow the road triple to shift properly. YMMV, of course.


This is a possibility, but certainly not guaranteed. Best to inspect the crank arm and spindle to see if there's damage, then decide if it's going to be a problem. Modern cranks can be pretty tough. I had an improperly tightened crank arm fall off, then rode several miles home with it a bit loose... and it's never given me a single problem since!

I don't think it's likely that I damaged it, I was dead tired from a very long day at work, and the ride home is easy, with long stretches where I just coast down a slight incline. If I did, though, I can put the original crank back on it.

I won't have time to work in it today, though I've tightened it down to what should hold it if it isn't damaged, and I've put a spare allen wrench in my work bag for today. Tomorrow I'll probably go about getting my hands on an empty peanut butter jar (My roommates go through lots of pb&j), and I'll give it a quick once-over with black spraypaint (thanks for that idea, Tourist).

My left crank arm came off of my single-speed, and kept loosening after re-tightening. I thought it was ruined. As a last ditch effort, I cleaned and greased the bolt threads and the bottom bracket faces. I then REALLY torqued the bolt down. It's been fine for a while now.

I don't recommend this except as a last resort. You could break something, but it was either that or replace the crankset.... actually I'm going to replace the crankset and bottom bracket soon anyway, as I don't like the (cheap) crankset.

Did you adjust the inner limit screw on the front derailleur? Might that allow it to shift to the small chain ring?

Uh... I don't think taking a tool kit with you everywhere is the takeaway from this experience.....

No, the Jamis came with double shifters, not triple, but the way it shifts, even with the original crankset, is odd - I have to shift up as if going up two gears, but going down once takes it all the way down. I actually tried it with the mtb crank (in my back yard, with the bike lifted off the ground), setting the chain on the smallest chainring by hand and shifting up. It worked, but the front derailleur wouldn't go far enough down to shift to the smallest chainring by itself.

Won't go low enough. Almost, but not quite. The front derailleur from my mtb might have worked, but sadly, it looks like Rowan was right, and the crank won't stay tight. It's not a huge loss though, or even a major inconvenience, as the original crank is still undamaged, and I was considering switching it back anyway. The experience has certainly taught me a few things though, which I consider more than worth the trouble.

Well yes, the somewhat greater lesson that I'm starting to grasp is more like "If you don't understand it REALLY REALLY WELL, don't %$#& with it."

The intermediate click on the shifter is a trim function, used to move the front derauilleur every so slightly to stop chain rub when in the biggest or smallest cogs on the rear. It's not meant to be a triple-shifter.

(Shimano did do a triple shifter in Ultegra that was adaptable between doubles and triples -- I have one and it works quite well).

Sorry about the crank, but you at least have an alternative.

What I do like is your attitude. You're looking for solutions by experimenting. Keep asking the questions -- perhaps directing the more mechanical ones to the Bicycle Mechanics Forum -- and you will certainly keep on learning..

That almost certainly will make your bike riding much more enjoyable because you know you are more self-reliant.

Over 10 years ago (before I got into touring) a neighbour had a garage sale and I bought an ill-fitting Chinese-made junker "mountain bike" for maybe $20. Once I fixed the flat tires it was not too bad at all - except for the poor fit. No matter. I put on a junker CCM rear rack and bicycled to my summer job as a lecturer at a local university. One day the left crank got loose so I stopped at a garage and torqued the bolt a bit. Every few days the bolt got loose again - as others stated. Finally I got some blue Loc-Tite and torqued the bolt one last time. It held ...

Each year when I return to my Mom's farm in rural Canada I take the Chinese-built out of the grainery and visit friends, still on their farms, by pedalling the gravel roads near home. The cranks have stayed tight, so the Loc-tite is still working.

I now have a custom built touring bike (my blue arvon1) and a BRG dis-assemblable mini-velo (the arvon2) on the way. I have come to the conclusion that nothing lasts forever, and if it stays together - then great. If not, then fix it as best I can in the situation I find myself in and seriously LOOK at REPLACEMENT. My arvon1 had a BB problem 5 years ago on the Savannah Way in Australia. A welder fixed the problem - temporarily because it eventually broke (again). Back in Canada another LBS (not the klutz who did the first installation) found the real reason and I replaced the cartridge with a PW which works fine - so far, after my latest tour in Australia. BTW, thanks again Rowan and Machka for your hospitality

Yeah, that's what I was thinking.

Just to put it in perspective, I used the wrong tool to remove my cassette a couple of months ago (I had an old freewheel remover lying around, didn't realize it wasn't the same thing as a cassette remover) and ended up accidentally pulling the axle cap off and removing the freehub body from my wheel. It turned out ok (with a trip to the bike shop) but for a while there I thought I had broken my brand new powertap hub. Gave me a bit of a scare.

Ah, I didn't know that about the trim function, though it does make sense. And self reliance is pretty much my objective - I want to be able to perform any necessary maintenence and simple repairs that might come up before I start doing tours longer than 1-2 days.

Mtn bike cranks are designed to use a 50mm chainline and road bikes derailleures are designed for about a 45mm chainline. When you put mtn bike cranks on a road bike without using a shorter BB spindle it won't work very well.

I have used mtn bike cranks on several touring bike by replacing the 110mm with a 103 mm BB spindle (68mm bottom bracket shell).

No worries! It was nice to see you again.