Mechanics and Fixing Any Questions Answered

Seat tube query for the hive mind. I have a frame with a 27.0 seat tube and want to use a 27.2 seat post (because dropper). Frame is alu and calipers measure the wall thickness at 2.45mm.

Two questions.

1. Is reaming out the tube possible and / or advisable?
   
2. If yes to question 1, is that something a workshop can do? or is that something for a frame builder?
   
   

Is reaming out the tube possible and / or advisable?

Many aluminium frames use a 31.8mm OD seat tube with a 27.2mm post, so the real surprise is that yours doesn't already

I'd take it to a frame builder because they're the people who will have a 27.2mm reamer

2002 Frame so the sizing is not up to more standard standards. I'll see if a 27.2 fits, if not then I'll work something out.

Thanks tester.

2002 Frame so the sizing is not up to more standard standards

27.2 has been "standard" since before the war🙂 but sometimes bike manufacturers are just dicks for no good reason

I've swapped a Quarq crankset, with GXP BB, over from one bike to another and for some reason it's binding when I tighten up the nds crank. I've tried putting spacers on the BB, but that's not helping. Any other ideas as to why it might be happening?

GXP needs 0 spacers. Measure your BB shell width, it may need facing

The drive side spacer remained on the spindle when you moved the crank over and there’s two spacers on the drive side?

Bb cups not tightened up?

I've tried putting spacers on the BB

Surely you want a negative spacer, if the binding is the DS crank pressing on the DS bearing then pushing the bearings further apart will only make it worse.

Measure the BB shell to make sure it's not a bit wide, if it is then facing a bit off will solve the above issue. The other things which can go wrong are the BB shell faces not being parallel, again facing will fix this, or the thread not being coaxial, which is much harder to fix.

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A little update, the bottom bracket is finally out.

Penetrating oil a couple of days and the non drive side went off easily. Drive side was still veeery stuck.

Decided to cut it out, went surprisingly quick with just a hacksaw blade. A tip is to use slightly dull ones for the last cuts, the aluminium is quite soft and you can feel once you start touching the steel threads without doing too much damage too them.

Thanks for the suggestions earlier!

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i clonked my rear mech on a rock yesterday, or at least I think i did. Anyway, after crashing through some boulders i have lost indexing. there’s no signs of impact but i thought the alignment looked iffy. i stuck a 5mm in the allen socket and cautiously pulled the hanger/mech outward but it hasn’t made much of a difference. keep yanking? it’s alloy. I have no spare. what should i do?

That's actually quite a decent BB, suspected so when I saw it in your initial post.

+gbj_tester can't for the sake of me recall the make. Help please?

Lots of possibility here, mech hanger, derailleur cage, bent cable inner and/or outer.

Help please?

Could be anything, that general pattern (cartridge bearings, lock rings both sides) is easy to make and as a result has been made by any number of boutique brands.

Anybody know where you can buy shimano step down ferrules for 4mm gear housing in the uk? Like these ones? Sjs has the 5mm ones only from what I can see

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Did you sort this?

I pulled the Quarq off the Mason to temporarily use my gravel cranks for Pendle 600k. I need to reinstall my gravel P2M on the Tripster (with the new Shimano BB because the MegaExo is toast) and then reinstall the Quarq in the Mason. Pretty sure there was only thin bearing covers/washers and no spacers in my setup.

Not yet, no. It's booked into my LBS on Friday for them to have a look.

Too short (stolen off another bike)? It shifts and runs fine, but looks a bit dodgy?

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Looks like it could well be OK.

Is the rear mech cage at maximum swing? Stay in that same gear and give it a nudge upwards from under the bottom pulley wheel - can the cage rotate a smidge further or is it at max?

I'll say bit too short, does the chain comes off the rear cog if you back pedal?

It’s still got a fair bit of movement to go and i rarely use 42-42 round here.

Just taken it for a spin and it seems fine, I can spin the cranks backwards a ok. It sound quiet as well. Just looks dodge.

It should probably be one link longer but will be reet.

I'd say totally fine then, as long as your shifting is good.

I’m trying to assemble my GXP cranks outside the frame. I can seem to get the NDS all the way up the tapered part.
I’ve got a shim/reducer installed, I assume the NDS crank should be closer to it than this?

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There would normally be a bearing there, which is what the cranks clamp to in lieu of preload.