griffin_

i'm pretty psyched and its nice and all but the minute i got home when i got on it i noticed the left crank was loose so i immediately when back to the shop and they tightened (i would have but it needs a 8mm allen wrench which is bigger than any of the ones i have) then i get home and hop back on it and its loose again. by then the shop is closed and now i'm pretty bummed that i got go back out there tommorow.
by loose i mean it kind of wobbles forward at the apex
is this just a looseness issue or does it sound serious?

anyway its really nice and feels so light but i have tried the fix cog yet

benk0

Hm... normally I'd say that after tightening it twice, that the taper is incorrect for the crankarm. However, that would be f'ing WEIRD for a prebuilt to have that issue.

griffin_

yeah i'm really bummed, i want to ride right now but i don't want to make it worse

poopncow

Tough break! btw, are you sure it is the crank arm that is lose and not the left cup on the bottom bracket? Also, there may be something caught between the BB axial and the crank that is preventing a full seating of the tapered sections. I would make sure that the shop removes the crank arm, clean the mating surfaces on the arm and the BB axial vice just cranking down on the bolts. btw, Which Phillie shop is it, so I can tell my sis and brother-in-law to never go there.

bostontrevor

Personally, I would invest in a decent set of allen wrenches. I have the Park AWS-11 which is great. Nice and heavy, takes all the torque I can feed into it.

Then take off your crank and make sure you haven't pincushioned the hole. If it looks good, put a little grease on your BB spindle. Ignore anyone who says this is a bad idea...there's plenty of good reason to do it and nobody can ever come up with a logical explanation for why not except, "that's just what I've been told. Now crank that bastard down. I've heard it described as face-shaking-tight when using a short hand tool like that.

The only thing you need to worry about is that if you over torque it, you can twist the head off the bolt.

griffin_

well i woke up early this morning and am heading back to the shop to make sure its fixed for good
i'll make sure they take the crank arm off too

skelly

What shop?

griffin_

keswick in glenside
outside of the city

darkmother

Most likely the crank is shot-riding with it slightly loose wrecks the taper. Get them to replace the arm.

griffin_

they are replacing the arm and the axle, the guy said both were busted

Aeroplane

Yay! I hope all is taken care of free of charge. If so, bikeshop++. Have fun on the rush hour.

griffin_

i picked it up for real today.
they replaced the bottom bracket and the left crank with a black one, so now i have a shiny chrome one and a black one, which i think is kinda cool.
they did it all gratis, which i totally expected, but he seemed to think i was worried about paying for so he kind of made a show of it
apperrently the brake cable guides are epoxied on so they might as well be braze-ons

any tips for getting the made in taiwan sticker off, its being a bit of a *****

max-a-mill

i am glad you dig the two different colored crankarms but....

if the bike was new and it was their fault it broke they really shoulda taken care of you a little better (LIKE GIVING YOU THE SAME CRANK ARM YOU DESTROYED).

sounds like they didn't put it together right. so you shouldn't have to put up with different parts.

just my thoughts, in the end, if your cool with it that's all that matters.

that is a cool looking bike from what i can judge by the website, i'd love to know what you think after you get to ride it for a little while.

griffin_

i'm not really sure as to whose fault the first crank being busted is, i guess it could be theirs but they remedied it well enough and did as much as i would expect them to do.
i think they might have a matching one coming in for me but i don't really care too much, i think i really like the black
o h and the arm is the exact same, its just black

anyway what are the symptoms of the cog coming loose? because i think it is, and how do i tighten it

Plinkerton

It's not your fault, that's for sure. And them being a place a business, they should be selling merchandise that's in tip-top shape.

Your cog shouldn't be coming loose either. That's THEIR fault. Make them fix it.

-Plink-

darkmother

Sounds like these guys don't know how to build a bike. Cranks that come loose on the first ride have not been installed correctly (likely) or are defective.

Don't ride with the cog loose, it will trash your hub. Enjoy your bike.

mascher

aaaaaa!

Careful with that cog. No offense to the wrenches, but most new bikes I've ever had or seen were incorrectly assembled. You urban US types might be fixie jaded, but I'd be most shop mechs are not at all familiar with them.

There's lots of threads on cog tightening, but a recent long-winded, self-important one (written by a newbie moron who just wrecked his hub) summarizes a lot of the more recent threads, and a number of things that they/you could/have/will do wrong dealing with threaded hubs and cogs.

https://www.bikeforums.net/singlespeed-fixed-gear/134125-before-you-strip-your-hub-read.html

mcsurf

you call yourself a poutineologist and he's a "moron". hmmm

bostontrevor

Unless you've had poutine, you know not of what you speak, blasphemer!

Mmm... Yum!

2manybikes

This is only what I "heard" too. So that's all it's worth. But I thought you might like to hear this one.

It did come from a guy who has been in the bike biz 19 years. That does not make him always right, but I tend to trust him. And it sounds logical to me. The grease allows you to tighten the steel post up into the aluminum hole too far, too easily, and wears out the square hole too fast. It just pushes the aluminum away and expands the hole. Then the number of times you can put it on and off is limited. On some cranks you can actually crack the aluminum around the hole.

The expanded hole also moves the crank in closer to the frame as it wears. Eventually you might have to get a new crank or a longer spindle to get a good chain line. I actually have been through that first hand.
I also "think" I saw something printed from Shimano about no grease too. I'll look for it tomorrow. I'm not 100% sure.

bostontrevor

Jobst Brandt has a good counter rant to that. (This includes how it's actually impossible to split a crank the first go round.)

Basically, for me what it comes down to is this: the pressure exerted on the interior of the crank arm hole is going to be the same for any given bolt torque, whether the spindle is lubed or not. Greasing the spindle will affect how deeply the arm seats as it will be able to slide further down for a given torque setting. THis is actually good as it makes it less likely that the crank will seat deeper later on and thus develop play.

However, it's not seating depth that ruins an arm, it's pressure against the hole.

I have first-hand experience that says that a crank is a lot more durable than the shaft of the fixing bolt.

Put another way, explain how greasing the spindle creates more pressure in the spindle/crank interface.

poopncow

Time out, Pressure against the crank arm hole is directly proportional to seating depth! When you push the crank arm deeper onto the taper, the interence between the hole and the plug becomes greater, i.e. the hole is the same size, but the shaft gets larger (ever so slightly). So for (pretend numbers) .25 inch deep, the shaft is .500 wide, but for .275 deep, the shaft is .555. The fit is tighter and there is a larger force against the walls of the hole. Aluminum is relatively soft, so everytime you torque the arm down, yu expand the hole and not all of it will contract. therefore the hole can get bigger with use (stop giggling...ok, I'm giggling too).

Lube does a few magical things.
1) it prevents corrosion and seizing. Alum and steel are not metals that like to be mixed. against each other, they form a battery, this is galvanic corrosion. But the grease acts as a barrier ...an insulator and prevents the circuit from being completed! corrosion between at the mating surface will seize the crank to the axle and erode the hole.
2) Alum is soft, it will want to schmear vice slide against the nice steel shaft. Lube is lube and allows for better sliding (stop giggling). better sliding will prevent the alum from deforming.
3) Friction is bad very very bad. For every unit of torque you excert agains the bolt, the bolt pushed the crank in the direction of the shaft. friction fights against this push, so the crank arms will not go as deep. Friction of the threads on the bolt sucks up some of that force too, so for a given torque, there is less force pushing. For all torque applications, the threads are lubricated. "dry torque" is always noted as the exception. Dry torque or dry sliding, or dry interfrrence is unpredictable. Lubrication is the equalizer and makes things consistant. Always lube tapers, splines and threads and torque to factory specs.

Hole deformation: will occur if there is too much pressure or too little pressure (and pressure is directly proportion to the seat depth which is proportionate to the bolt torque)
too much pressure (seat too deep) and the pressure will deform the hole
too little pressure (seat not deep enough) and the radial preload on the hole will not be enough to counter the cycling load and unload as you crank. You wnat to keep the minimum pressure at a level. below that level and the result is fatique or beating the hole bigger.

poopncow

btw: locktite also acts with much of the characteristics of a lube when it is wet or dry. Very counter intuitive, but its true... basic threaded joint physics and can get way long winded

mascher

Happily the moron and the poutineologist are one and the same. Or unhappily.

darkmother

Poutine is serious business, friend. Love the mess!