azjpeg

I recently bought my first Specialized bike - a Sirrus X 4.0 gravel bike. I've had it about 3 weeks and have been riding it 4-5 days a week, about 6-12 miles per ride. Yesterday while riding, I felt the left pedal go loose and then immediately fall off - luckily I wasn't going too fast and was able to stay upright. Wondering if this is likely due to loosening during the initial break-in period or if it may not have been assembled correctly? Is this something I'm going to have to check and tighten regularly?


Also wondering if anyone has tips on how I can best learn about maintaining this bike? There's no "user manual" and everything on it requires tools. I'm not a total novice, but it's also more complicated that the Treks I've owned.


One other note: the bike shop where I bought this is currently closed because an employee tested positive for Covid last week, so I'm on my own for a bit with this. Trying to borrow a torque wrench so I can put the pedal back on!

sch

Torque wrench should not be necessary. Pedals need either an allen wrench (could be 6 or 8mm) or they will have
a flat for a wrench. Wrench will need to have jaws less than ~1/4" wide to work however. The L pedal has L handed
threads. You need to closely examine the crank pedal threads (female) for damage as riding with a loose then
falling off pedal could well have messed up the crank threads. This is usually obvious from inspection, some of
these can be salvaged and some can't. Without an informed eye you might try installing the pedal from the back
side of the crank and use the pedal to clean up any minor damage to the threads and then try installing it the
proper way. A SMALL (!!!) amount of loctite thread locker might prevent future similar. If this happens again
you may need to have the crank fixed or replaced.

Pedal install is a do it once and forget, because the normal pedaling motion tends to tighten the pedal thread
into the crank. It is unusual for pedals to loosen on their own and the usual complaint is 'can't remove pedal
it is too tight'.

bikeaddiction1

Are the pedals new and do they spin freely? A properly lubed pedal that spins freely should turn the treads in as you pedal keeping them tight. If the pedal is really dirty or has a broken bearing etc. and doesn't spin somewhat freely, then the bearings may not be turning as intended it will then try to turn the pedal out.

If the grease is just a little stiff, installing them per sch's comments should secure it while it loosens up.

himespau 

Yeah, make sure you thread it in the correct way.

ClydeClydeson

Was it just the perdal or the whole 'crank arm'?

pedals seldom come off if they are only the weeest bit tight, but square taper crank interfaces are notorious for falling off if they aren't propely tightened during assembly (usually at the factory in Asia).

As an added bonus, if the crank arm fell off, it is very likely damaged from riding with is loose and will never again stay attached to the bike. Replacement crank arms are about twenty bucks.

azjpeg

Ah sorry, seems I did not give proper information - it was the whole crank arm that came off. And the bike is brand new. The two pieces are basically grooves that fit together and tighten.. the part attached to the frame says "Samox" and the crank arm itself says "Tighten to 12-14N-m by torque wrench". It does look like there is some slight damage to the metal. I've got great photos, but can't post yet since a newbie (I'll go make some posts to get me there!)

Appreciate the responses. Seems I should take back to my LBS when able to see extent of damage and if replacement is needed...

HillRider

Absolutely, take that bike back to the dealer and have it repaired properly and that probably means having the crank replaced. There is no reason for a new bike sold by any decent bike shop to have that happen as the dealer should have gone over the bike for correct set up before you ever bought it.

himespau 

Yeah, if it's a square taper bottom bracket (the axle that the crank slots into is a square) check the corners of the slot it slides into in the crankarm. If they're at all rounded (and there's any play in the crankarm when you put it back on the bottom bracket), that's not a good sign. If it fits on nice and snug and the corners are fairly tight, it's less of a problem. I wouldn't worry too much about torque. I have a torque wrench for this situation, but I've never been able to overtorque that bolt. Maybe you could if you used a big cheater bar, but undertorquing it is more the problem. A little locktite on the threads might not be a terrible idea, but only if you're sure that the crankarm is fine. Others with more experience might disagree with me about the locktite.

Edit:I'll aggree with Hillrider. For a 3 week old bike, this is on the shop to repair, not you.

Koyote

This. Riding with a loose crankarm may have damaged it, so the shop needs to deal with it. Totally a warranty issue. Don't address it yourself.

FWIW, these things happen, even with good shops. My shop recently put (back) together one of my bikes after having the frame repainted, and the crankarm came loose after about 1,000 miles...When I took it in, the mechanic apologized profusely, and told me that, some time after working on the bike, he had realized that his torque wrench was malfunctioning. They replaced the crankarm and the pre-load cap, used loctite on everything, etc. Stuff happens.

Cyclist0108

That should not happen. Might be a warranty issue. You need to have the assurance that it is done right. That kind of screw-up could injure or kill someone. If it is Specialized, any Specialized dealer should be able to help, and they are reputable and will do the right thing.

August West

Sounds like a Shimano crank since that is exactly what is printed on the NDS arms. What does the drive side say? Something like "Deore"?

Regardless, this is something that needs to be addressed by the dealer since there may indeed be damage. Tough situation with them being forced closed. You could try to reach out to Specialized, explain the situation and see if there is anything they could do for you.

Does is look anything like this?

himespau 

specialized's website says that model comes with Suntour Cranks with a 68 mm BSA crankset, which is why so many of us are focusing on square taper.

Le Mechanic

It seems like lots of folks are confusing the pedal with the crank arm. Assuming the pedal came loose from the crank arm, the bike should definitely be returned to the dealer where the bike was purchased. The reason it happened is that the pedal was not properly torqued when the bike was assembled. It's actually happening a lot lately with the high demand for bikes. Some shops are under a lot of stress to get a lot of bikes that are sold build. Corners get cut, lots of interruptions from the phone constantly ringing, pedals not tight, a bolt here or there not torqued, then things come apart early on. I've repaired 4 of these last week from a competitor's shop. Same thing if the crank arm fell off. Generally, the cranks are attached to the bike out of the box, but they're not always torqued to spec.

himespau 

In his updated post, he said it was the whole crankarm.

fietsbob

seen in # 11 ; Left crank arm is akin to a threadless stem. plastic cap snugs up the 2 bearings, the 2 pinch bolts hold that adjustment secure..
and the crank on the splined tube..
maybe step 1 , done, and not step 2..

Cyclist0108

The problem is without a picture, we have to make the best guess:

That sounds like pinch bolts, not a square taper bolt (which typically require about 40 Nxm of torque).

Since we don't know for sure, and any instance where the crank-arm falls off of a new bike is potentially a major problem, and the bike is under warranty, the advice to take it to a Specialized dealer seems the most appropriate. You or I could do this at home, but I am guessing the OP is better off not learning on this example.

azjpeg

I was able to get a call through to the bike shop - they said its a known warranty issue with this bike, and Specialized has been sending replacement parts. I went to the Specialized web page for the bike and there are now 4 reviews saying the left crank arm fell off (all written within last 3 weeks) -- and I wrote my own review, which is now pending. Would be a good idea for Specialized and bike shops to at least issue a warning about the issue, or even a full recall if its widespread before someone gets injured. Hoping the replacement part is not just the same thing and actually fixes the issue!

Cyclist0108

The best outcome is they replace it with a different, better, crank.

alcjphil

Crank arms are installed in the factory, pedals are installed either by the shop or the owner. If torque settings are not done properly in the factory, crank arms can fall off. It may be nothing to do with the actual components, just faulty installation

Pop N Wood

Bit of an oxymoron as it was the bike shop that sent the bike out with a loose crank arm.

I say fix it at home so it can be repaired properly.

In fact, I would take a moment and tighten every nut and bolt on that bike. Check the spoke tension while you are at it.

dedhed

With the shop saying it's a "known issue" you would have thought they would check it or at least warn the customer it might happen.

alcjphil

A "known issue" is only known after a number of owners have reported it. It takes time before that problem is reported to dealers so that they can check the problem out. I would not place any blame on the dealer, I would place the blame where it belongs: the factory where the bicycle was built and the company that contracted the factory that built it

WizardOfBoz

Good follow through. I just wonder what the heck the defect was. This shouldn't happen.

WizardOfBoz

I would let the LBS install it under warranty. Maybe ask "Can you show me how you torqued the bolts? What torque setting do you use?" when they install the thing, so you can SEE that they've got the arm retention bolt torqued properly. I'd probably ride the thing around the block, cranking hard, and then ask them to retorque the bolt.

BTW, to add my voice to others: If the crank arm loosened gradually, and its a square taper, and you rode it almost any distance at all, the crank arm is toast. The taper will never hold the arm on reliably. A new crank arm is needed and I'd insist upon it.

Pop N Wood

Or alternately you could do it in your own driveway in 2 minutes.

BTW, not square taper crank.