Gallery, Projects and General > How do I??
Anyone a Mountain Bike Expert?
jcs0001:
Sparky:
A few comments but please keep in mind that it's been a few years since I've torn one of these apart.
The frame looks decent and having front suspension is nice. I've got a very similar bike (a kona). Having rear suspension might be easier on the butt however it tends to add quite a bit of weight.
I believe the brakes are V brakes - in a cable style brake they are quite decent. Changing the pads and adjusting them should make a big difference. You could also give the rims a bit of a cleaning as that will make the brakes work a bit better. Retrofitting disk brakes might be quite a bit of work and expense.
Not sure if the bottom bracket on your bike is uncaged/caged ball bearings but if so then a good cleaning and new balls with some good grease may help - it's a cheap fix and worth trying. I had a bike a long time back with that system but the threads had problems - installing a sealed bearing bottom bracket/axle was the only thing that fixed it.
Wheel bearings/races - not sure on this but I suspect that they also have a ball bearing set up. Replacing the bearings may be all you need to do and it's quite inexpensive. You can always upgrade to a new wheel/hub but it can mount up in price fairly quickly.
Shifters/derailleurs - New cables, chain and rear cluster and possibly the two plastic idlers on the rear derailleur should make it shift quite nicely. Keep in mind that cables will stretch so you may need to do some adjustment after a few km. on the bike. You may have to learn to be subtle with the shifting :).
You will need the proper tool to remove the cluster - I install the tool, held lightly with the nut on the axle and then mount that tool in a vice so that the wheel is horizontal. Turning the wheel will give you some leverage and make it easy to remove the cluster.
Can't help with the give in the suspension. You may be able to check out another bike or two and see if it's similar or something to be concerned about.
Patuca - very nice old bike with the reynolds 453 butted tubing - that's good stuff.
John.
sparky961:
Don't have much time to comment tonight, but I have brought the bike into my workshop as my next somewhat long-term project. After watching more YouTube videos than I care to admit, I have a pretty good idea what I'm in for. I'm a bit disgusted by the number of custom tools required for each assembly and every version thereof. It does, however, look like an opportunity to "make something useful" out of metal. Certainly cheaper to buy the tools, and I will if making them is a no-go. But plan to make the attempt for the majority.
I did try to use a simple puller to get the crank off the square taper off the bottom bracket (what a dumb name, eh? call it an axle or a bearing assembly). That wasn't successful, so this tool will be the first one I make.
I'll document what I can here in pictures.
jcs0001:
Sparky:
You likely have seen the puller you need to remove the cranks - if not I can take a photo of mine. They are very simple and work well without scratching things up.
John.
sparky961:
I've made a small amount of progress since the last post. It is, however, very satisfying to write that the first custom tool was a success.... at least the second time around.
Opening up the plastic cap pressed into the pedal crank reveals a bolt and some much larger threads
Thinking I'd be smarter than the people that sell all the custom tools for bikes, I figured I'd just use my handy little puller to get the job done. If trying this yourself, don't bother. There's too much deflection, too little grip, and not enough force to get the job done. It just made a mess of the aluminum where the fingers were digging in. No harm done though, I'll just clean it up a bit when I reassemble. Oh and YES, I did have the bolt undone. I replaced it loosely to give something solid to push against.
It's tool making time! I read about a guy that successfully made this tool from aluminum and since I have a bunch of round stock I gave it a try. Threading is a pain to set up on my machine but with a nice big undercut to run into it isn't bad to machine.
As things turned out, the tool above didn't quite thread in. I measured the pitch diameter later at work and it was right on what it should be. So why didn't it fit? I think the threading tool form wasn't quite ideal and there was a lot of tearing and such. The threads didn't look great - which is a good indication whether they'll work or not. I got it to thread in a bit but it started galling and making a mess of things so I stopped and went back to the drawing board.
No worries. CNC makes things so much easier. :) About an hour of effort produced a new tool with absolutely perfect threads. Oh, and this one is 4140 HT steel. The setup was reversed from how I did it manually and I left a long stub that I could hold in a collet block to put the flats on. The external thread is a non-standard M22 x 1. The internal thread is 1/2-20 UNF which was drilled on the CNC but tapped by hand. It's iffy tapping a one-off hole on the CNC lathe with the tools I have available.
Lots of grease was added to get the most pressure with the least friction. I could have used a slightly longer bolt but, again, materials at hand. I ended up sticking a smaller SHCS down inside the hole to take up some extra space and give me enough length to pull the crank arm off the taper.
I was able to remove one side of the bottom bracket without any special tools. Really big pliers did the trick without any damage. That said, after what I found I'm not planning on trying to salvage any of the parts. I'll be installing a new sealed type as long as I can find what I need. I've been known to pedal through water that's above the bike's axles, so that's likely the cause of some of my troubles.
I still need to come up with a way to remove the nut on the drive side of the bottom bracket housing. It's really not the brightest design in my opinion. It's round with two very small flats - which don't give much to get a grip on with traditional tools. Can anyone confirm that this is a left hand thread? It would make sense and I've seen a few references to this fact online.
RussellT:
I've always found the easiest way to undo those is by picking the bike up, holding the two flats in the vice and turning the bike.
I can't remember which side is LH threaded but one is - so if the one you've taken off is RH - then this will be LH.
Russell
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