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

68 lost souls wrote: »

There's definitely some road rash on it, I can see where it took a hit and the chain was wedged in and twisted in it so I had to wrangle the chain free.

Hanger snapped and needs replacing for sure but not 100% sure about the derailleur, I guess I'm just worried that if its bent in anyway it might cause another failure. Theres scratches and marks where I can see it took the brunt of the fall

I might wait until the hanger is replaced and test it on the bike stand and then the turbo before heading out on the road.

When looking at a derailleur to see if it is bent, check whether there is good parallel alignment between the surface that faces the hanger, and the surface at the bottom of the parallelogram section of the derailleur that interfaces with the plate of the swing-cage (red lines in the pic). If these two surfaces are not fully aligned across every potential gear position (observe whilst operating it with your hands), then the parallelogram section is twisted, and the derailleur is toast. If the parallelogram is ok, but the swing-cage is not fully aligned (the one in the pic is a bit crooked), it can usually be realigned by clamping the hanger-bolt tightly in a bench-vice (align the derailleur carefully with the vice's jaws, so you can use the vice as a reference point) and using a water-pump pliers to gently align the cage in stages, working in one direction/plane at a time. To align the jockey wheels themselves, if required (they can still be crooked even when the cage they're in is straight), grab the two ends of the jockey wheel bolts tightly (while the derailleur is still in the bench-vice) with the water-pump pliers, and twist them into alignment.

cletus wrote: »

Disc brakes on my bike, but I make sure to give the disc a liberal application

You'd be surprised - a few times a year, people come into the bike shop with their rims or discs covered in oil, saying that the brakes had been squealing, and that they had added oil but that it hadn't helped...

cletus wrote: »

I'm a teacher. I'm rarely surprised by stupidity

You, sir, have just won the internet.

fixXxer wrote: »

How difficult is it to change a back tyre? Went across something last night and the tyre is completely flat. Was going to do it myself but looking at the gears and all the rest as a n00b, I might just wheel it down to the local bike shop tomorrow and give them the business.

Its very easy, although as you note, slightly more difficult on the back. Once you open the quick release (assuming thats what you have) the wheel should just pop out (well, depending on your brakes, I suppose). Once you've changed the tube, just make sure the chain is on the top of the cassette (back gears) when you put the wheel back on. Have a look at the video below

magicbastarder wrote: »

as above, but worth noting it's more fiddly getting the wheel back on the bike if you've disc brakes as you've to be more precise lining it up.

It does have break discs. I've seen puncture resistant tyre mentioned in a few places. Are they genuinely a benefit or a marketing gimmick?

fixXxer wrote: »

It does have break discs. I've seen puncture resistant tyre mentioned in a few places. Are they genuinely a benefit or a marketing gimmick?

I also find wearing gloves while doing the job isn't a bad idea, the grease from your hands can make the discs squeal if it gets on them.

The brake is snapped off, or the boss is snapped off?

For the two bikes I had that had v-brakes, you used an allen key to remove a bolt that went through the brake arm and into the centre of the hollow boss, and once that was off, the brake arm would come off fairly easily.

EDIT: Oh yeah, I get it. You want to remove the boss from the fork. Ok, sorry.

This any help?
https://www.youtube.com/watch?v=P54TWF-BaDI

brownian wrote: »

Ooo - it didn't occur to me that the boss (which is snapped - with about 10mm sticking up of a stump) might be hex-centred. That would be great, were it true... Will try tomorrow. Thank you.

No, alas, I misunderstood the problem. The boss hole is almost certainly circular in cross section. That adjustable wrench-cum-vise grip in the youtube video looks like it might do the job anyway, but he implies that the boss should have flats of some sort, if it's removable.

This video says that if's a steel frame, the boss might be welded in. It shows the flats are at the base of the boss on the bike he's working on.

https://www.youtube.com/watch?v=cgBgfNdkDj8

cletus wrote: »

Actually, right, this might work. If you can get a sleeve with the correct inner and outer diameter, cut it to length, and thread a bolt through into what's left of the boss, the bolt head would keep the sleeve in place, and the brake could pivot on the sleeve.

That's very clever. The bolt might gradually bend under the force of braking, but if the sleeve is flush with the remnant of the boss, maybe the sleeve would transfer some of the force to the boss.

brownian wrote: »

Thank you, cletus (and tomasrojo!). I'll need to lay hands on a vernier caliper, but I might come back to you (cletus, thanks again, that's very generous) when I have this.

I'll need to have some solution before C-mas.....

Where are you located?

Brilliant! When I get the caliper to hand, I'll maybe post a picture or two to show the 'stump: there's about a cm or a little less of the original boss. The base 6mm or so are one diameter, the rest is slightly less (this latter being the remains of that part of the boss which passes through the actual brake).

I adjusted the cleat on my left foot today. I felt the heel needed a bit more outwards. Had a second thought, I'd loose the bolt if went ahead. So went ahead and lost the bolt after 25k. Nearly fell to the ground on stopping, as the cleat was turning on the one remaining bolt, wouldn't release my foot. I managed to clip out in the very last second.
Solution thread locker? Or should give it more tightening? I was afraid of breaking it. Maybe it was too much of an angle turned, I'd say 30 degrees form straight ahead.

Yes. But not going to. I will replace the missing bolt. I was just wondering are there other means not to drop the bolt to the road when it worked itself loose.
And the other thing, I reckon had the cleat at out of normal range angle, that's the reason for why it got slack so soon.
Oh, sorry, I'd have mentioned that this an SPD system, due to liking more float on my roadbike.

Prior to dropping the bolt, did you have two bolts in your cleat? Once the bolts are seating flush, the angle of the cleat shouldn't make any difference. Whern you get the new bolt, take a picture of the cleat position, and the bolts as you have them positioned

It could just be a case that the bolt wasn't nipped up tight enough. A dab of blue threadlock should remove any doubt

padyjoe wrote: »

No, I tightened them by hand. I'd have paid more attention to it though.



Yes, I had 2. To be honest I've used for a long time without an issue. I'm partially putting the blame on this: the cleat serrated edge leaves marks in the sole as it bites into it. If I change the position, some of the teeth go into an unmarked surface, the others grip into existing holes. This way allows more movement on the marked side, even it feels tight on screwing, it could let go under stress.

Seems likely. Once you have them back in and positioned correctly, I'd be inclined to check them after maybe 10km, and nip them back up if necessary