This could probably be subtitled “never volunteer for anything”……….
So, someone in a social media group posted a cry for help with an issue on a Spinning Machine in the small private Gym they use. The issue was one of those typical “where is the noise coming from” posts but included some video. It seemed to me that the chainring was rubbing in the guard for some reason, most likely a worn bearing. Subsequent diagnostics included the crank being a bit wobbly. So the potential diagnostic included a loose crank.
Further chat revealed that they didn’t have anyone who knew enough or had appropriate tools to take a more detailed look but it turned out that the gym was not far from me. So, interest piqued off I go for a free lunch, sort of.
Well initially the diagnostics looked simple. The drive side crank was definitely wobbly and the crank bolt was definitely loose. So tightened up the crank bolt and gym member started to give it a trial. All seemed well until they cranked up the resistance and then stood on the pedals. BANG. The drive side parted company with the rest of the machine. Ooooeeerrrr. Broken axle.
Seems that the crank had been loose allowing leverage on the end of the spindle which, from observation of the broken surface, had been part broken for a while and the rest gave up the struggle.
Kinda simple but then the “fun” started.
In theory these things are standard(ish) and you’d expect them to use standard bike parts/tools. However, neither of the 2 crank extractors would fit the cranks, despite the manufacturer website clearly showing Park Tools extractor. So I need to get the broken bit out and also find some way of removing the left side crank to replace the BB.
The broken bit was solved by resorting to a sacrificial bolt and a bigger hammer.
The LHS is still to be resolved but I’ve got hold of a windscreen wiper remover that may do the job (but might be too lightweight) and ordered a 2 leg puller that should have more oomph to extract said crank.
Then there is the BB. The manufacturer web site shows a custom axle and press fit bearings. The machine in the gym has a cartridge BB! So I had not taken any tools to extract a cartridge BB.
Further investigation shows that the first models of the machine did have cartridge BB and I can get them a replacement but need to get the existing one out to find which type it is.
Given what I have found so far I’m wondering whether the machine is British or Italian threaded. Can’t find any details on the manufacturer site so that could be interesting – might have to see if I can get any response from the manufacturer.
I’d hope it was British (LH thread on RHS of the BB) as I’d suspect a spinning machine to be prone to more procession vs a bike as folk crank up the resistance to a higher level than you might need on a bike – but is that too sophisticated for the tooling to make these things? I’d rather be able to fit a standard Shimano cartridge BB back in there if possible as they are also way cheaper than the manufacturer’s spare and its a small private gym who do not have oodles of dosh.
The saga will continue once I return this week with different tools to try to get the BB out……………
Sometimes that’s how it feels working on my bike!
As a toolmaker, CAD/CAM/CNC guy. I’ve re-tapped so many threads on a bike, as well as reproducing derailleur hangers, head stem bolts, removing seized seat post and head stems, and I’ve come to your conclusion, you’re stuffed!
Unless said spin bike was involved in this?!
Does your said gym have equipment insurance? If so, implemented it!
other than that, I’d be taking spin bike to my workshop and CNC mill out the BB and insert/press in new cartridge BB.
Milling it would cost more than the thing is worth!
Maybe someone was practicing that routine on the machine and that’s why the axle broke!
That is seriously impressive though.
Someone owes you a massive amount of beer if you get this thing fixed.
Progress has been made – wait for Part 2………..