MTB 3x9 to 1x9 conversion... part deux.

A few test rides quickly demonstrated that a single-speed specific 'narrow wide' chainring was needed (the chain dropped whenever I went all the way down the cassette).

I went for the Race Face 'narrow wide' (cheaper from the US on eBay).

http://www.raceface.com/components/rings/rings/single-ring-narrow-wide/

Half the weight and easy to install... and it looks pretty good...

Let the testing begin...

Raspberry Pi hack #1

Floppy music...

Starting with a clean or dirty SD card..

1. Ensure the card lock is disabled
2. Download chose distribution
3. Use Win32DiskImager (or FlashNul) to write OS image to SD card.

I chose Noobs (Raspbian) then started from scratch with a Raspbian image because I'd downloaded loads of chuff onto the SD card.

4. Run config - sudo raspi-config
5. Change hostname
6. Expand disk
7. Enable SSH
8. Reboot
9. Install Xrdp - sudo apt-get install xrdp (to allow RDP connection)
10. Use Notepad++ with NppFTP plugin to edit (python) and putty/plink to execute.
11. Test GPIO by enabling the 'SD' onboard LED (goled.py)

Pin assignments for floppy music:

What I've done with Sugru

I can't remember how I can across Sugru but it has great potential and I've already used some to...

- Attach a four-way adapter to a tiled wall

- Block holes where mice can get in

- Fix kids' toys

- Make a grip for a slippery USB stick

http://sugru.com/

MTB 3x9 to 1x9 conversion...

Some history...
Having recently bought a new Orange Clockwork, I've been getting used to regular Rapidfire 
shifters, which has been a real departure from 20 years of using thumb shifters. In trying to get to grips with the opposite action of the shifters for the front and rear mechs, I realised that I rarely used the granny ring or top ring...

This may have been due to the different gear ratios I now had and also the bigger 29er's.

I was also keen to see what sort of weight saving I could achieve.

So I decided to go 1x9...
I'd done a fair bit of reading on other conversions and the pros/cons and decided that for now, at least, I would simply remove the inner and outer chainrings and replace the 34t sprocket on the cassette with a 36t.

I had the stock Shimano HG50-9 11-34 cassette on the back and an Alivio 22-32-44 crankset up front, so I would lose the occasional 4:1 maximum for speed but at the other end, I would effectively lose 1st, 2nd and 3rd gears - no big deal... might just mean a few more hills out of the saddle.

First job... more teeth
To get the extra two teeth I would need on the cassette I discovered the cheapest (but not the lightest) option would be to get hold of an HG61-9 12-36t and merge the two cassettes together. So I kept 36t-18t from the HG61 and added the 15t, 13t and 11t from the HG50 (see photo above). Not my idea though...

http://forums.mtbr.com/drivetrain-shifters-derailleurs-cranks/11-36-9-speed-cassette-you-can-do-667135.html

Second job... unwanted teeth
Then, remove the unwanted chainrings. Luckily Father Christmas had bought me a nice Bike Hand toolkit so I used an 8mm allen key and the universal crank puller with the round ended adapter to remove the drive side crank from the Octalink bottom bracket.

Then I removed the chainrings using a 5mm allen key and the special chainring bolt tool - hard work because of the lashings of loctite that had been applied in the factory.

I then reattached the middle chainring with some short chainring bolts and some loctite.

Third job... fewer links
As I already had the chain off, I checked to see if it could be shortened now it was running from 32t at the front and 36t at the back (10t less from largest sprocket to largest chainring). I took out a few links and the rear mech now hangs at about 55% so it may be too short but a few 'road' tests are now required to check. 

Calculated weight saving is around 750g... not to be sniffed at.

Then...

The other outstanding issue is whether or not I will need a chain device of some sort to stop the chain flying off the chainring, particularly as it's still a regular middle chainring. Having read up somewhat on the issue, it may well me the case but what I intend to try first is a single-speed specific 'narrow wide' chainring such as...

http://www.raceface.com/components/rings/rings/single-ring-narrow-wide/

Longer term...
I may well consider a shorter, and perhaps, clutched rear mech. For now, I will run with it as is.

More useful info...

http://www.bikeradar.com/gear/article/workshop-how-to-convert-your-mountain-bike-to-1x9-or-2x9-gearing-29342/

http://unluckypete.com/2013/03/why-single-chainring-is-enough-for-trail-and-enduro-riding/