17

I started getting seriously into bike work circa 2002 and was lucky enough to come across Jobst Brandt's view of the topic around that time. Since then, most of which time I've spent working as a mechanic, I've observed that the Brandtian observations of the mechanical dynamics at hand are wholly correct, but I don't agree with him on what to do about it. He ...


11

Judging from your videos, it appears that the chainrings and crank are no longer connected. It appears that you have something called a one-piece crankset. If you are confident that you can learn how to disassemble it, I’d say you’re up for the repair. Once you have the crank off the bike, you’ll be able to see how the chainrings and crank arm are connected. ...


9

Carbon is the dominant frame material in performance bicycles. You can't thread carbon. There are two ways to get bottom bracket cups into a carbon frame: bond (industrial-strength glue) an alloy sleeve into the shell, or use a press-fit system. You are potentially adding several manufacturing steps by adding a threaded sleeve to a carbon frame, and the ...


9

Threadless cartridge BBs have their place, and that place is where the threads are destroyed. Thankfully you're not there yet. They are a compromise because they tend to have creak issues sooner or later no matter what. You should take the frame to a shop with a proper piloted BB tap set. One side of your shell looks fine. The fix is to install the pilot ...


8

Some mechanic might have put a liberal amount of grease in the BB shell and also in the head-tube prior to assembly. Then copiously greased the seat-post as well. Grease has a tendency to migrate, especially in hot weather and move to the strangest places, the bike may have been stored upside down, head or tail-up. Think of it as a gift from whoever put it ...


8

Modern cranksets either have 24mm-ish width spindles, or 30mm-ish spindles. DUB (28.99mm spindle) falls into the latter category. GXP spindles (24mm, tapered to 22mm on one side) fall into the former. Almost all press fit bottom bracket shells can take cranks with 30mm or similar spindles. Trek’s BB90 bottom bracket standard appears to be an exception. That ...


7

You're going to need to replace the entire BB. The drive side cup is reverse threaded. (This isn't true of older bikes of certain nationality, but the nylon cable guide suggests yours is new enough for this not to be a concern.) To answer your questions: The squareness of the cups is very important for the BB to function. To get the cup out without ...


6

While we don't have your bike in hand, or at least a video of the issue, it sounds more like your freewheel or your freehub has failed. I suspect that new cyclists might say the gears have failed. Edit: This answer actually mis-diagnosed the problem (albeit I'd argue for good reason - it was given before videos were provided!). I'm leaving it up for general ...


6

The sleeve provides a tiny amount of extra protection for the bearings and is not structural in this instance. They are often fiddly to fit on these "boutique" bottom brackets and even people who deal with them frequently can cock up the tube alignment from time to time. You may be able to break it up with a screwdriver, if it's brittle enough, to ...


5

Nathan's answer covers it all, but to expand on the last point... That cup is dead. Your last resort is to cut the cup out - I've done it once. In my case the bearings had failed, and the rider was rubbing the BB axle on the cup directly, slowly eroding through the casting. The cup would not turn even using the correct BB cup wrench a park HCW-4 You ...


5

SunRace spec sheets show the crank bolts should be M8x1.0. The bolt diameter is 8mm and there is 1mm betwween thread peaks. This size is by far the most common. However there are other standards. Truvativ seems to have the most variations using M8, M12, M15 plus some self extracting bolts. If the bolts starts but binds it is likely the right diameter but the ...


5

What you need to do is look up the total capacity specifications of both your front and rear derailleurs. For a front derailleur the total capacity is just the largest difference between the largest and smallest chainring tooth counts the derailleur can handle. The total capacity is for a rear derailleur is the largest (difference between the largest and ...


5

Once you get the bearing and cup off the spindle, you can assess the state of the bearings a little. Turn them with your fingers while pushing hard in both the radial and lateral directions. This kind of test isn't perfect because the loads applied in use are so much higher, but sometimes it can reveal notchiness or roughness that lets you know you'd be ...


5

Probably ISIS splined. That’s the only one with splines of that length with the smooth end. https://www.sheldonbrown.com/bbsize.html


5

This looks like a standard British bottom bracket with a fixed cup and adjustable cup. This article gives a good overview of how to service. It looks like your lockring is missing. Also, it doesn't look like you'll be able to use a pin spanner on the adjustable cup. Not clear from the photo what kind of wrenching affordance the cup has, but it should have ...


5

Park Tool Repair says greasing the spindle is 'an option', but says it is to prevent corrosion, rather than having any effect on how the crank goes on the spindle. Slathering grease on is seems like a waste as most is going to get pushed out of the joint.


5

This question about loose crank arms has been asked and answered several times before on this site, but yours is the worst I've ever seen I think. Unfortunately your crank arm is ruined. If the alloy crank gets loose and is ridden on the hard steel spindle wallows out the relatively soft alloy. It does not matter how tight the retaining bolt is done up the ...


5

There is an issue with putting anything between a Hollowtech bottom bracket cup and the frame. A cartridge bottom bracket is not very sensitive to its position being changed relative to the frame shell a little by the chain case mounting bracket. The axle just gets moved slightly towards the drive side. The hollowtech cups are more sensitive to their ...


5

You are taking the right approach to figuring your chainline per a given spindle, but yes, there can be other limiting factors. If you go too far, it is possible for the crank body near the spindle interface to smack into the bottom bracket shell or the cartridge body, or be low-clearance enough that flex and grit wear a groove into the crank. Low-profile ...


4

I did end up completing this project. I talked to several people, just calling up bike shops that sold or specialized in belt drive bikes and asking for opinions. I spoke with someone—I think it was a fellow at Ben's Cycle/Milwaukee Bicycle Co.—who had lots of experience fitting belt drives to frames. He had even worked with Gates on building several belt ...


4

It's set by the crank, and is like this because GRX is targeted at 135mm/142mm rear ends. GRX takes the same BB as any HT2 road crank. It's enough to matter, but chainstay length is the other piece of how much it matters. Doing this kind of thing on super short chainstay bikes can yield pretty compromised results in terms of number of rough combinations, ...


4

Of course, but be aware that there are patents (for the design) and trademarks (for the name Hollotech 2) applicable and the compatibity might be in two separate aspects. The first aspect is the compatibility of the cranks and the bottom bracket. Here it is enough that the crank spindle of the correct 24 mm diameter and the right length. FSA Megaexo 24mm ...


4

You cannot fit a threaded bottom bracket into a press-fit shell frame. A threaded Hollowtech II BB for road cranks will only fit in ISO threaded bottom bracket shell of width 68mm. GXP is a crank axle standard not a BB standard, so that does not tell us what the press fit cups in the shell are. What you need to do is measure the cup diameter and shell with. ...


4

The reason I have always heard justifying PF bearings vs outboard bearings is that PF bearings allow the frame to be wider and stiffer in the BB area without increasing the Q-factor of the bicycle. PF is also lighter because it does not require a metal threaded insert. I have two bikes with PF bearings and I suspect PF frames are a lot like gnocci. When ...


4

Money. Threading holes is a process that has to happen during manufacturing. Both sides have to be concentric and parallel, and the taps used to make the threads have to be pretty good, so they wear fast. By comparison, the bottom bracket holes on a carbon fibre frame can be made in the layup process, and (in theory) should come out the right size ...


4

The amount of wobble shown in the video is fairly typical, for better or for worse, which is not to say it's a good thing or that the FD adjustment can necessarily be free of rub in all combinations and under variable load with it. You don't have to worry about this getting worse if you leave it alone. For what it's worth, you can multiply your "AA AB BB BA"...


4

First up, there's no shame in getting a local bike shop to do this bit of assembly. Your frame is expensive and damaging the threads would be very bad. Your frame is threaded - you need to use a threaded bottom bracket. The press-fit adapter you bought is not suitable for this bike. The cartridge in your tea-towel photo is the correct unit to install. ...


4

There's every reason to suspect that problems with the bore tolerances and/or alignment are causing it. That's become a common theme of creaky BB issues. It's a good idea when the cups are out to take what measurements you can to see what's going on. Bore tolerances are easy to measure but alignment for the most part is not. The thread-together models from ...


4

In general, you may be able to check the bike manufacturer’s page for your bicycle. They will usually list all the components the bike is built with. However, the list may not be comprehensive, especially if the manufacturer mainly sells lower end brands. Bottom bracket standards can be confusing, because there are a number of variations. In this case, you ...


4

If you can identify the specific part number on the crank (or just by looking at pictures online), Shimano provides a great deal of information online about compatibility. For example, if you are using the current Tourney FC-TX801 crank, it uses a standard threaded square-taper bottom bracket, so any square taper crank will work. The SORA R3000 crankset you ...


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