Now here’s an odd looking mountain bike.
What do you think?
You may have been wondering what happened to the BMC mountain bike restoration project I started a while back.
Like many projects it got to the “nearly finished” stage and sat there for a good six months causing a nuisance to the family.
Good news that it’s now moved on to the “basically finished” stage…
It was cleaner, but is now dusty from riding. So apologies for the photos, but it’s great that it’s rideable!
On an earlier test ride, I noticed the left pedal crank creaked on the downstroke, which it didn’t on my first test. This suggested a worsening issue, so I inspected further.
Anything other than a smooth bottom bracket/crank is bad news. A lot of torque goes through there, plenty to cause damage pretty quickly if not addressed.
I found an allen key large enough to remove the pedal cranks, and discovered a Shimano Octalink bottom bracket. This is the first Octalink system I have owned, with all my older bikes having square taper BBs.
I also found the non-drive side (left) mating splines to be slightly chewed at the end. Apparently this is common with Octalink systems, and happens when the crank arm isn’t perfectly aligned, prior to screwing the crank arm bolt back on. So, as I had never removed it, this damage was done by the previous owner, though it seems odd it didn’t creak on the first test ride.
In short, the crank arm is toast and needs replacing. The BB itself is in good condition and runs smoothly, so is perfectly reusable, but as Octalink is no longer common, finding replacement crank arms was an issue. Basically I could only find a new Alivio set which would be fine, but for the fact it wouldn’t add to the overall look of the bike.
After a little cogitation, it dawned on me an alternative might be right under my nose…
Some time ago I rescued a binned Steppenwolf hardtail MTB frame with some components still attached, including XT cranks and a more modern external bearing BB. Why not see if it’s the same width as the octalink BB?
Lo and behold it was, so I would theoretically be able to replace a Deore LX crankset and Octalink BB with an XT crankset and modern external BB, at no cost. Not bad at all and 100% eco-friendly.
One problem. Don’t have the right tools!
As systems evolved, so the tools needed to work on them change. Though this a consequence of welcome technological innovation, it poses something of a challenge for the home mechanic.
A regular crank extractor tool doesn’t work with an Octalink BB. To remove a BB on a vintage bike you need a hook spanner, an Octalink BB needs a BB removal nut thingy (like for a cassette but bigger), and an external BB uses another type of large spanner with slotted splines. Consequently, you often need different tools to work on various bikes.
The bike shops near me aren’t really set up for the home mechanic, so buying tools is interesting and expensive. Apparently, in Switzerland, folks like to get other people’s hands grimy instead of their own (which probably makes sense).
As I quite enjoy grimy hands and torn knuckles I set about looking for tools and stumbled across a sale on Chain Reaction for an 18 piece toolset, for 50CHF delivered, including some tools I had already, everything I needed for this job plus a couple of extras. Pretty good deal, and arrived within a week.
Once the package hit the doormat, like a child on Christmas morning I ripped it open and within 20mins had replaced and upgraded BB and crankset and chainrings to higher spec parts. Great!
The toolset is made by X-Tools, and though I was hesitant about quality given the price, I am quite pleased.
The “new” drive train all works perfectly and it’s always most satisfying to complete an long term unfinished job.
So the moral of the story is, if you can salvage used parts, do so. You never know when you might need them and they’ve often got lots of life left.
Secondly, always invest in (quality) tools. Even if technology changes, and you only use them a few times, they pay for themselves quicker than you think.
Also, that which is new today will be vintage tomorrow, so there will always be more bikes to work on!
A while back I picked up a trashed Specialized Hotrock kids bike. The frame looked sound but everything else was pretty far gone.
This bike would need far more workshop time than it’s replacement value, so it’s owners rightly binned it and moved on. But it’s a decent size for my son’s next bike, giving me enough time to fix it up before he can ride it.
Among numerous other issues, the derailleur hanger was bent, chain broken and derailleur was in a sorry looking state.
I straightened the derailleur hanger with a pipe wrench plier and then set to the derailleur itself.
It’s pretty straightforward to service a derailleur, remove, clean, degrease and regrease jockey wheels then reinstall. But it’s a bit of a dirty job, so rarely gets to the top of the DIY service list.
After getting it completely wrong, I removed the jockey wheels again and correctly rerouted the chain, using the smallest cog and chainring to give enough slack to work with.
Total bench time, maybe 40mins on a rainy Sunday afternoon?
Though I have absolutely no experience with dynamos, nor any real idea how they work, last Sunday I decided to tackle the non-functioning rear light from the Tigra ladies’ bike.
This bike has a dynamo installed, even though it is not such an old machine. I was recently told that in Germany it is illegal to ride a bike with battery powered lights. I’m not sure if that is true, (German cycling laws here…) as it does sound pretty nonsensical, though I’m pretty certain you are allowed to ride in Switzerland with whatever lights you want.
Once I figured out how to engage the dynamo so it would work from tyre rotation (this seriously took me a few days of prodding and pulling to figure out), the front light functioned fine but the rear refused to shine.
First, I removed the plastic housing and checked the bulb. Filament looked ok. Checked continuity with the multi-meter, all good. Screwed it back in. Crossed my fingers. Nothing.
Then I had a look at the wiring. The dynamo has two wires coming out of it, one for the front light, another for the rear. Not sure how this can make a complete circuit, but I guess that’s not necessary for DC power. The bulb socket seems to be connected to the mudguard itself, so presumably being grounded is sufficient for a DC circuit. My lack of electrical knowledge is by now apparent.
The wire hanging out of the bottom of the dynamo seemed loosely connected, but I noticed a spring-loaded connector in the bottom which holds it in place just fine. The wires head into the rear mudguard, then follow a crimp in the side until exiting through a hole in the rear, into the light fitting. This wire is then connected to another metal clip, basically wedged into a bent flap, held in place only by the “springy-ness” of the metal itself…
The wire going into the rear light fitting looked a bit corroded, so I took it out, sprayed some white vinegar on it (helpful for oxidation), dried it, rubbed it with some steel wool. The copper colour shone nicely, so I “re-twizzled” the strands, rubbed the metal clip with the steel wool and reinserted the wire. Crossed my fingers. Tested it it again. Nothing.
Then I removed the bulb and filed a tiny bit off the bottom to ensure good contact. No joy.
I now removed the wires from the dynamo and did the vinegar, steel wool and “twizzling”. Crossed fingers. Tested again. Nothing.
Not to be deterred, I removed the bulb again, and found bits of spider eggs or some other insect leftovers. Blew those out. Another round of vinegar, steel wool, scraped a bit with a screwdriver, dried it, sprayed a bit of WD40 on it.
While I was at it, I sprayed a bit of WD40 on the metal clip and the wires at the dynamo. A bit of WD40 often works wonders.
Screwed the bulb back in. Crossed my fingers. And it worked!
A well earned cup of tea followed. If only every Sunday were so productive!
It’s been a while that disc brakes have been seemingly considered dangerous, and are occasionally permitted and banned in professional road bike races.
Personally, I never really understood the cause for concern, and RJ the Bike Guy’s latest video does a really neat job of clearing this up.
Check it out.
I guess you have heard of a removable valve core, but what about an entire stem?
I recently added another abandoned bike to the workshop and while tending to the flat tire I noticed the inner tube held air, but that the valve stem came out of the inner tube if fiddled with (with an explosive release of tyre pressure too!).
While I assume this is a fault in the inner tube, on closer inspection, it doesn’t look like anything has torn or failed. The inner tube has two rubber joints, the second of which seems to hold the stem base. The upper seems just to hold it straight.
I have replaced the inner tube with a new one from Schwalbe, but can a removable valve stem really be a thing? Never seen this before.
I recently bought a tired BMC Fourstroke FS04 mountain bike, which had seen plenty of action and not enough maintenance.
I saw potential (or as much as anyone can from a couple of mobile phone photos…) and brought it home to breathe new life into it.
Sometimes you get lucky and there’s not much wrong with a bike. And sometimes there’s some skeletons in the closet, though finding them can also be fun.
I’m always itching to give new project bikes a good wash. Often so quickly that I don’t get any “before” photos… I’ve got to learn some patience!
Washing a bike gives you the chance to look at it closely and spot things you previously overlooked. The BMC was superficially lightly dirty, but chain, chainrings, cassette and jockey wheels were well overdue a de-griming. Is half of restoration actually just cleaning?
Now funky shaped frames are great, but who wants to clean their bike with a toothbrush after every muddy ride?
Overall, the bike is sound, frame is good, components all there. There’s a few dings, but no visible evidence of crash damage – especially important for aluminium frames. Brakes are ok (if a bit spongey), rotors are true, headset is fine, BB has no wobble.
The front hub was loose, so I stripped and repacked it with new grease. Bearings were fine, races good. This was sorted very quickly and only minor adjustment was needed to the disc brake caliper to avoid rubbing against one pad after tightening the cones.
The rims are slightly out of true. Usually I use rim brake pads as a makeshift truing stand, to see minor wobbles and where to adjust spoke tension. Truing wheels on a bike with disc brakes will be more tricky, so I’ll leave that for later…
The biggest fault the seller mentioned was the twisted derailleur and chain. The derailleur looked ok, so I removed the hanger with the intention of replacing it with a spare from the Steppenwolf, but found it was a slightly different shape and wouldn’t fit.
A trip to the bike shop later, the mechanic told me he didn’t have any spare hangers in this shape, but he could bash it straight for me. Back home I reinstalled it, stripped the derailleur, serviced the jockey wheels, reinstalled the derailleur and chain (minus one link), and wouldn’t you know it – it worked perfectly! 👍
If you read my earlier post, you may recall the seller mentioned his local bike shop quoted almost twice what I paid for the whole bike to sort this out (presumably replacing derailleur and hanger).
Turns out that was pretty poor advice as I sorted it in two hours (including an hour’s walk to the bike shop and back with the kids), at zero cost (a contribution to the tip jar was all they would accept – but I also bought some cleats). Some adjustment needed for perfect indexing, but 80% there. Result!!
Next I adjusted the handlebar position, flipped the riser stem down and adjusted brake and shift lever positions, taking the opportunity to lube/grease all the screws that hadn’t been loosened in years.
While poking around I found a couple of other issues: a sawn off seat post (kids, just don’t do it…!), a loose pedal spindle and some broken chainring teeth, but overall this is turning out to be a nice little restoration project.
Watch this space for the next steps!
Science Communication, Art and Adventure
Welcome to Cycling on the Continent. A blog following a young explorer on his travels around Europe.
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Because being outside is awesome. Because traffic sucks. Because no carbon. Because cool people. And most importantly, because I love riding my bike.
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