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Hi there, if you're not already sorted I have a Specialized Air Tool you're welcome to borrow/use, in E14 by Canary Wharf:

alright Benson, yeah already replaced the 3 dodgy cells, the remaining 37 were fine, but pack still doesn’t seem to be charging, have a feeling the battery management system is knackered, but not sure how to tell.

Alright Phil, unfortunately the ebike is well out of warranty, about 4 years old now. Will be a shame if I can’t fix the battery pack as it’s a decent Giant model and in good nick otherwise.

Edit: I did think the battery management system could be the culprit, so measured the voltage leaving the BMS and feeding the battery and that seems to be 32V, perhaps a bit low, but thought it might be balancing its output with what it’s detecting from the battery?

Hi All, I’ve been sinking deeper and deeper into an ebike battery pack rebuild rabbit hole of late. My mother rides an ebike, it was her main way of getting about, but then she left it unused for ages during lockdown, and sadly when she went to use it again it wouldn’t charge up.

From the research I’ve done this seems a common problem, where some of the cells in the battery pack can get over-discharged when left unused, then the battery management system will prevent it being recharged.

Anyway so thinking I could somehow revive the pack I went ahead and dismantled the battery to find it comprised of 40 Samsung 18650 cells, arranged in a 10 series x 4 parallel configuration. I have a basic knowledge of electronics so broke out my multimeter and found one row of four cells seemed to be the culprit. While 36 of the 40 cells registered a reading around 3.4-3.6V four of them were down around 1.2V.

Having watched a bunch of videos about reviving 18650’s cells I ploughed ahead and tried a few methods to bring the four dead cells back to life and succeeded with 1 of them, but disappointingly the remaining 3 were toast. So next I sourced 3 matching Samsung 18650s, same chemistry, capacity, discharge rate etc.

Those new batteries arrived in the post today, so using a separate charger I charged them up to about 30% capacity and would like join them back to the original nickel strips but don’t have a spot welder. I know I could carefully solder them in place, but this will damage their capacity, so am trying to blag the use of a spot welder, but as a temporary fix I’ve used little magnets to hold the batteries in place while connected to the nickel strips.

It’s hard to tell if the magnets are actually providing a good contact, but in this set up I reconnected the battery’s battery management system then connected the charger but the battery still doesn’t seem to be charging. I’ve tried measuring the voltage across the pack and it’s reading 32.6V which seems about right for a flat battery, and I read 42V coming from the charger and going into the BMS, so I think power is getting to the BMS fine.

Does anyone have any experience or ideas what could be going on with this battery pack please? I’m running out of ideas! Cheers Kev

Hi All, I’ve been sinking deeper and deeper into an ebike battery pack rebuild rabbit hole. I’ve diagnosed the problem and am now ready to replace a few of the cells, but to join them properly I need a spot welder, so does anyone have one I could use briefly please? I imagine it’d be easier to bring the battery pack to you, but please let me know if anyone has access to one, as I’m really keen my Mum back on the road, cheers Kev.

Your welcome mate, hope the tour is fun, fingers crossed the weather holds up.

Pm'd!

Think I have the adapter you need, based in E14...

Still looking....

Thanks for the kind words Joshua, glad it wasn't super dear to me, no sentimental value, but obviously still sucks and just goes to show how many opportunist thieves there are out there... Also, found a photo of it:

My own fault, got too relaxed, so annoyed with myself.... plus I only just bled the brakes y'day, lol.

Ha, that's a good one way of reminding yourself yeah... I've only got myself to blame, was aware I'd locked it that way, but only meant to leave it that way temporarily while home before bringing it indoors this evening, that's when I discovered the theft, so annoyed with myself.

I should know better but got complacent with my MTB as this was right by my front door while I was home, had it locked with just the rear wheel secured with a D-lock and a cable through the frame, and just discovered this, lesson learnt:

Just had my MTB pinched from right outside my front door. I'd foolishly only locked the back wheel with a D lock and ran a cable though the frame, so the thieves just cut the cable leaving the back wheel behind, schoolboy error. Must've happened in the last couple of hours, it's GT Avalanche 1.0, black frame, Rockshox forks, Hayes Sole hydro brakes.... What an idiot!

Edit: bike was locked up in E14 by Westferry Pier.

Dibs PDWs pls

Nice one Gerry! I actually may be able to help you out with the Joe Blow pump you're after.

My sister in-law had both wheels pinched off her town bike over the weekend. She did lock the bike while at Brockley Park with the kids, but only through the frame, so I'm looking for a pair of wheels that are 8spd Shimano/Sram compatible please. Any colour and condition really as long as the rims are wide enough to accommodate 35c tyres upwards. Thanks in advance!

Same, only ever seen those Problem Solver covers. Maybe someone could 3D print some?

Dibs the Spoon pls, pm'd

Dibs the cassette please...

Hi All, this is a massive long shot but does anyone have a spare mech hanger bolt knocking around their spares box please? I managed to lose the nut from mine during a rebuild. The type I need is the two piece nut and bolt sort like the picture below and it needs to be 9-10mm in diameter... Thanks very much!

It's unreal, why hasn't a manufacturer addressed this, probably as it's not a common enough problem to make it worthwhile, but given when it does happen it's such an ordeal you'd think some sort of seize resistant post would exist or a reliable method of extracting them.... I'd love to know how that Mr. Seatpost guy does it.

@littleK you know it mate.... so relieved, gave it more thought and decided against drilling it with your 25.4mm drill bit.

@ffm thanks, that's an interesting approach, that instrument mouthpiece tool reminds me of a bearing puller. Yeah chuffed I managed to get this out, it was an absolute ball ache, and took some Mcgyvering!

Here's what I did, it was a saga, but maybe someone can benefit from my experience:

Firstly having stripped the bike down completely only then I realised the carbon post was seized in the alloy frame, so went ahead and sprayed some Plus Gas penetrating fluid through the seat tube bottle cage bolt holes and left the frame inverted for a fortnight. After daily top ups of more Plus Gas the post still wasn't budging though and I was getting worried that the Plus Gas might be reacting with the seatpost paint/lacquer, causing that or the carbon to swell, but couldn't find any info online so charged ahead.

As the post still wasn't moving and without access to a vice I thought I could improvise using a G clamp to grip the post's alloy rail clamp against a cast iron metal railing in my front garden. God knows what my neighbours must've been thinking....

As the post was quite a nice one I was trying to be careful but eventually the G-clamp bit into rail clamp so I figured the post was toast and gave it some welly. With some careful twisting proceeded by a loud cracking sound the post moved a bit, hurray.

Everyone knows once you've broken that seal it's usually only a matter of time and eventually the post will come free, so I was feeling pretty optimistic, but the post would only twist side to side, and only a few mm at a time, plus I felt if I kept twisting the post by the rail clamp eventually the clamp would break free, as they're only epoxied in place.

I then realised that the rail clamp must have a small alloy insert that sits in the carbon tube, so if I could grip the post in this area the post should hold together under twisting, but the only way I could think of doing this was with a proper vice.

Enter @littleK who came to my rescue and let me use his bench vice. Initially we did the same as before gripping the rail clamp and twisting the frame and did manage to move the post by about 5mm. Suddenly though the inevitable happened and the rail clamp gave way, so whatever adhesive that was holding it in place had given up the ghost... Bollocks!

In hindsight at that point we should have clamped the post at the section where the alloy insert was in the carbon tubing but instead I hastily thought if we clamped the post horizontally along its length rather than vertically we would grip the post better and I could pull on the frame more easily whilst twisting. But horror of horrors this just ended up cracking the post! Everytime we re-clamped the post the tubing would just squash, meaning we couldn't get a good enough grip on it, plus the bench itself wasn't fixed to the floor meaning it kept moving, preventing us from applying enough pressure.

By now I was running out of ideas and thought some method involving cutting or drilling would be necessary, so @littleK lent me a 25.4mm drill bit and the plan was for me to try cutting the post near the seat tube and reaming it out with a power drill.

A couple of days later, and having given this more thought I was leaning against drilling. Firstly I didn't think the drill bit would reach down far enough and was worried I wouldn't be able to get at the remnants of the post, especially any material down deep in the seat tube. If you look at the frame the seat tube has a narrower section which makes contact with the post that's only about 80mm long, then the tube widens. So I thought drilling could leave a loose section of post down in the seat tube.... A horrid reminder and unacceptable.

I figured I needed to know how much post was actually inserted into the frame and managed to remove the loose rail clamp, then by attaching two spokes together using a nipple I fashioned a depth gauge which showed me there was about 270mm of post below the top of the seat tube.... not good news.

With that much post inserted I thought trying to cut down there successfully would be super tricky and I was going to give up but then thought maybe I could use a couple of stems with 25.4mm clamps attached to the post as grips to pull and twist the post out. I thought the clamps of the stems would grip the post from all sides so wouldn't crush it. The plan half worked, but as before the post was only moving sideways as it was hard to pull and twist at the same time with enough force, and worse after a few attempts the stems started to lose their grip, not unlike my own state of mind by this point.

The stems were slipping as the post was still deforming under compression, when I had a minor brainwave and thought I could attack the issue from the inside by using a quill stem inserted into the post with some old flat bars attached and use those to twist and lever out the post from the frame.

Having found a suitable stem and bar combo I hulked out on the post but still could only twist it marginally, and by tightening the stem I could see the post starting to bulge and split. To counter this I used one of the a-head stem clamps to brace the area that was bulging. This was the final set up that I thought would work if I could only get a good enough grip on the post.

Enter my local VW garage who luckily are literally at the end of my street, and with only minor bribing let me use their bench vice. This one was bolted to the ground and having clamped around the post with the quill stem on the inside and the a-ahead stem bracing the outside I gave it the beans and the post started to budge, result.

As the frame was quite elevated it was hard to exert upwards force while twisting, and the whole time I was conscious of damaging the frame, but slowly the frame started to snake up off the post. 30 hernia inducing minutes later the post was out. I used the orange tape to track my progress and the post was tight right up to the end. To my surprise when it was finally out I inspected the inside of the frame and it was really smooth and clean. The only residue was some black powder resembling soot, so I think it must've been the post that swelled.

Anyway, happy ending, moral of the story is always use carbon assembly grease on carbon posts!

Deep deep joy: