the 'there's no such thing as a stupid question' bike maintenance thread

Went out to the shed when I got home from work, Weepsie. Unfortunately, I don't have a bolt, or a threading die, of the right size.

I will be in Ted Johnson's hardware on Thursday. They have the widest range of odd sized hardware I've ever seen. If they have a suitable bolt, I'll pick one up, it'll only be cents

New bike coming in February (I hope!). It’s 11 speed GRX. Current bike has 10 speed Tiagra cassette , but the rear wheel is 11 speed,compatible with a spacer . I’d love to be able to swap wheel sets between the 2 bikes quickly without having to change cassettes etc. Is there a way of setting up them to be compatible with one another?

Why does my chain sometimes drop off the small chainring when slowing down to stop? The front derailleur is correctly adjusted, and it happens only every few weeks. I can't figure out what the cause is. I have a chain catcher which I've yet to fit - I'd rather fix the cause than the symptom. On the other hand, perhaps the existence of chain catchers indicates that it can happen even with a correctly adjusted front derailleur.

Are you 100% definite that the front derailleur is correctly adjusted? in my experience they are more finnicky than the rear derailleur.

Other things to check

Check the crankset and bottom bracket

If the crankset is loose, it can move sideways during pedaling, which can allow the chain to come off. So make sure the crankarms are securely attached and that there’s no side-to-side play in the crankarm or bottom bracket. Some bottom brackets can be tightened. Worn out ones will need to be replaced, but they’re not overly expensive.

Check the chainrings

If the chainrings wobble side to side, that can throw the chain off, too. Loose chainring bolts can cause this, so check all of them with the appropriate wrench to ensure they’re tight. Once you know the bolts are tight, check the chainrings to make sure they spin straight and true. Just sight from above as you turn the crank by hand. If there are wobbles, you should true the chainrings or have it done (you don’t need new chainrings).

Check the lower derailleur pulley

Sometimes the lower pulley (called the idler pulley) will be misaligned with the chain. Since its job is steering the chain correctly, when it gets bent, it can cause the chain to drop. The easiest way to see this problem is to stand behind the bicycle as someone else shifts through all the gears. The pulley should remain perfectly aligned with the chain. If the chain is trying to come off the side of the pulley in some gears (usually toward the outside shifting limits), gently bending the pulley back in line could solve your chain drop.

Edited to add: have you checked that the serailleur is alligned correctly with the chain?

I'm sure it's correctly fitted, but of course that means only that I'm sure that it's correctly fitted, not that it's correctly fitted :)

I fitted the crankset myself (new build with new drivetrain) and everything was torqued to spec. I didn't think of checking the chainring bolts, I'll check those, thanks.

I've checked the RD as well, as far as I can see it's spot on.

I think I may be running out of talent here so it might be best to have Joe Daly take a look (they did a lovely job of truing a wheel for me the other day btw).

Thanks for the suggestions!

No except you must use carbon paste and not grease to lube inside the seat tube. If you use grease, the seat post will keep slipping down.

Yeah, just google bolt on skewers, security skewers, or allen key skewers

The cranks on my bike are not spinning freely. I took them off and the bottom bracket on drive side whilst turning is a bit rough/gravelly whilst on non drive side it’s very difficult to get it to spin/turn at all. It’s a press fit on an alu frame, about 6 years old. Is the bb toast or can it be cleaned in some way?

If it is toast, is it worth buying the tools to extract and fit a new one myself? I like to be able to do most things at home but am wondering if replacing bb is a step too far for someone who just tinkers around? Maybe with an alu frame there’s less chance of an expensive cock up?

I've had this on the bike for near 5000km now and I've only just changed the battery this morning, very easy to do. Simple to fit to the crank and very cheap. Also connects easily with the Garmen. Would recommend if you are looking to keep costs to a minimum.