Mechanics and Fixing Any Questions Answered

After wearing through the skid plate on my 6800 front derailleur. Have people ridden without or am I going to do horrible damage to my chain / derailleur???

Should have one by mid next week but also don't wanna skip the weekend cycles

You'll be fine.

So mini-velo time - this is my Dahon - it has a silly suspension fork - Kinetix q fork by "German A".

Blakburn local rack - fits pleasingly using a mystery threaded hole in the back of the fork and doubling up the stays with domed washers. It doesn't foul movement of the sus' parallelogram doodar. The front hub on the wheel is a kinetix sealed bearing job with. The bike is 7005 double butted alu.

Mainly the question is... is this death ? uncharted waters but wondering if engineer/mech peeps out there would have a take on it ?

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Dunno, but both sets of brake pads look like they're in the wrong way round.

Might help to get a brake cable and lever on that front calliper too.

Yeah - it was late - its work in progress

hilarious

Looks atrocious. Would ride

Can someone please tell me what this is called and if it’s usually available as a spare? Came off a Stout 36/26 triple crankset.

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It’s called dirt, it’s hard to come by. There is also some rust.

Those are found on unserviceable chainsets. The whole chainset normally goes in the bin.

(or you put it back on and keep riding until it becomes physically impossible)

dirt, it’s hard to come by.

And I just chuck it away. Good to know.

Those are found on unserviceable chainsets. The whole chainset normally goes in the bin.

Aye, that’s my experience and frankly desire for this entire Spez hybrid. Was hoping to save my customer some money but don’t know what the part is actually called, other than ‘fused chainring’.

Just found a £20 triple from decathlon, that’ll do.

What am I missing here,

Left is a 68x107 un55
Right is a 68x110 un55

Driveside axle projection is identical, the extra length on the 110mm is all on the nds.

Surely it should be 1.5mm either side?

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You'd think so wouldn't you!

You could try a bodge using a ~1.5mm BB/cassette spacer on the DS cup?

I’ve actually fitted a longer bb that seems to be a better fit (stronglight 45d cranks working with a track hub) but the 11m was one step on me getting there for sorted and I was confused by the spacing.

Square taper BBs aren't necessarily symmetrical. The detailed specs will tell you what the DS and NDS protrusion will be.

The 110 seems to be particularly asymmetrical. Presumably it's designed for a specific chainset model - maybe to push the left crank out to match the extra width of a triple on the right hand side.

Can’t seem to find this info from shimano themselves but someone in this thread has posted a chart with measurements of a load of different sizes of un55 and it does seem the 110mm is a bit of an anomaly being 3.5mm longer on the nds than the ds, all the other sizes are 1mm or less of difference between the two sides.

I have a SRAM Red yaw FD that isn’t aligning both lines with the chainring when I tighten it up. I’ve tried to take a picture but it’s next to useless. Whenever I tighten the braze on bolt, the rear of the FD is some way further out than the front of the FD. Is it normal to require some sort of shim to alter the alignment? If so, where would you find one of these? It was previously on a bike that I crashed, so perhaps it was bent in that but without another yaw FD to compare it to, I’m struggling to work out whether it’s bent or I’m just mechanically useless

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But do you need the lines? They're good to get you in the ballpark but ultimately I'd angle it in a way I can cross chain without rubbing. Of course if it's going out of line every time you tighten you may be missing a shim.

The setup guides I’ve watched suggest you use the inner limit screw to move the cage out, align the lines F&R with the large chainring and then tighten the braze on bolt. As soon as the braze on bolt begins to be tightened it pulls the front in and the rear of the derailleur moves out to the point that the chain is fouled, I can’t keep them aligned. Trying to work out if this is a shim issue or the derailleur was bent in the crash

If you can't compensate by lining it up too far the other way so that tightening it brings it into place I reckon you've bent your braze on. Those mechs have little supportive things on the back to butt against the frame that you pick the right one and move into place, but it doesn't look like you have one.

OK... potentially very dumb question, but given my propensity for ordering parts from the internet only to realise I've measured something incorrectly/forgot to measure it at all, I'm trying to be a bit more cautious rather than assume I know exactly what I'm doing despite having never replaced a BB before...

Replacing the BB on my early '00s trek. Measured up the BB shell and spindle length which comes out more or less as ~68mm shell, ~110mm spindle (see pics). Before I go ahead and order this Shimano UN300, am I missing anything? I'm keeping the triple chainring that the bike came with.

Should be fine.

You could check spindle protrusion on each side, i.e. how far outboard from the frame's BB shell the current BB spindle extends. If it's symmetrical then go ahead and buy a symmetrical BB. If not then go down an internet rabbit hole looking for the assymmetrical one.

Final consideration is ISO vs JIS taper, but unless it's a Campagnolo chainset then it's highly likely to be JIS (Shimano use this standard).

Ta very much! It's more or less symmetrical, maybe +/- 1mm but don't think that'll make a difference...