Mechanics and Fixing Any Questions Answered

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  • Has anyone experienced a crankset bolt loosening off despite being torqued up properly?

    I've got a BB30 crankset that has been remarkably quiet for several years but has recently started creaking a lot. It seems the self extracting bolt keeps working itself out and introducing play into the BB. Should I just torque it up tighter (currently going up to 40nm) or should I perhaps look at replacing the bolt? For what it's worth I've also applied some threadlocker on the bolt but it still seems to work itself loose after a hard effort.

  • it will be the crank arm which is rounding out and causing the bolt to work loose. unfortunately theres no repairing that, just need a new crank.

    have a look and see it will probably be going round instead of square, if so, thats the problem. in the interim you can tighten it up loads and go for a ride, keep an Allen key with you to nip it up as and when.

  • I've started lending a hand at a local bike recyclery and am struggling a bit with the perceived correct balance between cost/waste saving and...doing things right.

    Currently debating with a 'senior' colleague whether pic attached shows unacceptable wear (to left side in pic). He says we can just slap some new bearings in, whereas I think it looks knackered and needs a new unit. The existing one is old, Chinese and made of cheese, and the bike was brought in with play in the BB.

    I'm not currently on site so haven't seen state of cups etc and I'm probably not going to start arguing with people after just starting out there, but I just wanted to know if I'm wrong to be bothered ?

    Don't mind being wrong, as if it means a working bike for those that don't necessary have a bunch to spend then it's all good. Just not what I'm used to.

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  • It all depends on what standard you're working to and why. If it's a bike with a loose ball BB like that it's probably a bit of a shitter and you're trying to make an affordable bike for someone that is safe and ridable, in which case whack some new bearings in it, adjust it as best you can and it'll probably feel a bit rough but work. If you're repairing someone's bike to a high standard then new BB erry day, except days like most when they're out of stock.

  • That bearing surface might be ok if there's no pitting and if there's not too much material taken off. Probably not acceptable for a paying customer in a LBS, but likely fine for a bike recycle place. Of course, the proof will be in the pudding when you assemble.

  • Cheers guys, yeah I guess it'll depend on how borked or not it seems afterwards.

    Agree the (lack of) availability of replacements is a significant factor too!

  • I couldn't find a general frame building thread, so I thought I would try here as my query is about treatment, once a frame has been built. I just took delivery of one of the last new BOB Yak trailers, which are now sadly discontinued. The frame is made of welded 4130 chromoly steel tubing. At many of the joints there are holes by the welds which have been left unfilled, an example is shown in the photograph below.

    I would like to prevent corrosion of the frame over time from the ingress of water. Should I fill the holes with black mastic; inject Waxoyl or Dinitrol before assembling the trailer; spray a teflon lubricant like GT85 or WD50 inside the holes from time to time, or something else?

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  • Bit of Dinitrol or similar would be best. Personally I like Dynax S50, but other brands of cavity wax are available, as the old saying goes.

  • Personally I like Dynax S50

    Thanks, that is a useful tip. I see Dynax S50 is available in inexpensive aerosol cans, which ideal for this application. I notice their injector will be too large so I would need to figure out an attachment to inject into a 2.5 mm diameter hole. If the spray nozzle fits on the same diameter stem as one from WD40 or GT85, then I could try using their straws to inject the cavity wax.

  • I want to try to straighten the cage from my bent ultegra. I’ve dismantled as much as I can and hammered the screw out of the cage axle but how do I get the rest out. More hammer?

  • More hammer?

    Whenever there’s doubt...

  • Hi Fred,
    I just wanted to pop back and say thanks! Finally got a mech and it seems to be working just fine. Much obliged for your suggestion/advice 👍🏼

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  • i guess a stopped clock is right twice a day

  • I'm building my wife a flat bar road bike for commuting. Have picked up a Tiagra 4600 chains but know nothing of Shimano-can I use any hollowtech bottom bracket cups or do I need specific 4600 series Tiagra ones (which are hard to find)? Frame needs BSA threaded cups...

  • 4600 chainset? Any hollowtech road BB that fits the frame is good.

  • that's great. Thanks

  • Are the RS700 series shifters the only flat bar ones I can use with ultegra? Or is one of the MTB shifters compatible

  • I think there were metrea ones and maybe microshift did a compatible one, MTB shifter will need an MTB mech, might be able to make the front mech acceptable but not good if you're using one, no trim.

  • It can work but watch out for two possible snags:

    1) Top tube length. Bike frames designed for use with flat bars will typically have longer top tubes than bike frames intended for drop bars (as drop bars add 70-90+ mm of reach). So check the TT length of this frame and do your sums with stem lengths etc.

    2) Brake pull. Check that your brakes will play nice with the 105 shift/levers. 105 shifters will pull a specific length of cable which is suited for road brakes. V-brakes require longer pull - suited to MTB brake levers. Cantis I can't remember! Disc brakes come in both forms, long-pull and short-pull.
    I'm currently using long-pull V-brakes on my tandem which has short-pull Tiagra shifters. I'm squaring that circle using a pair of travel adapters - Taiwanese copies of the more expensive Problem Solvers adpaters.

  • Canti and road calliper lever pull are interchangeable. As are drum brakes :)

  • Thanks. I was hoping someone would fill that gap in my memory.

  • I have a sram crank with an inner bearing race seized to it.

    The whole bearing came out when I pulled the cranksets out the bb and then the outer race cracked and fell apart when I put it in the vice.

    I’ve clamped this inner race in the vice and tried knocking the spindle out of it (using a block of wood to protect the end) and no bueno. I’ve also poured boiling water on it and stuck in the freezer for half an hour or so and then did boiling water again to try and break the bond but same result, no budgie.

    I’ve got it back in the freezer to try again but any other recommendations greatly received.

    I’m trying to gradually increase the violence/destructiveness. I think I could cut through the race but this might damage the surface on the crank where the bearings sits, could give it some fire but there’s aluminium on the crank boss and spider area and the crank arm is carbon so…

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  • Would a crown race puller fit on the crank spindle?

  • Unfortunately not.

    The base of the park crp1 is a bit chunky to fit in there and the ‘plunger’ doesn’t come down far enough to hit the axle.

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Mechanics and Fixing Any Questions Answered

Posted by Avatar for OmarLittle @OmarLittle