Saturday, October 19, 2013

Wolftooth Chainring Install & First Impressions

After last week's Fatbike Adventure ride, my 9:zero:7 needed some serious love. The bike was still covered in mud, and the bottom bracket was making some serious grinding noises. I had some time tonight to attack it, and I decided as long as I had everything apart, it was time to install the Wolftooth components 30T 104BCD chainring.

These chainrings have the wide/narrow/wide profile to prevent chain drop even without a front deraileur or chain guide. Also, they have a cool chainring design that allows installation of a 30T chainring in the middle position- normally a 32T is the smallest you can go. Not only are these rings cool, they are also made in the USA- specifically Minneapolis. I rarely if ever use the granny, and going to a single small front chainring should work just fine, along with simplifying the bike and saving weight.

With the cranks off- I could directly inspect the bearings. The non-drive side bearing seemed OK, but the drive side bearing sounded like it was filled with rocks and felt about as smooth. I don't have any spare 6806-2RS bearings laying around. Rather than waiting for new bearings to arrive, I popped the seal off with a X-acto knife, sprayed it out with some degreaser, let it dry, and packed as much Park Tools grease into the bearings as I could. I kept on rotating the bearing and applying more grease until the grease coming out looked mostly clean. Even after the grease packing they still feel a bit rough. I'll order another set of bearings and install when these start grinding again.

After the bearings and cups were back into place, I could swap out chainrings, put everything back together, and remove the now-unneeded front deraileur and cables. The chainring install actually turned out to be a big weight savings:

+41g: Wolftooth 30T 104BCD chainring & 4 chainring bolts

-163g: Shimano XT Front deraileur
-71g: 32T Chainring, 22T chainring, chainring bolts
-165g: SRAM X7 front shifter, cables & housing

Total: 358g weight savings (0.78 pounds)

It looks great on the bike. Hopefully it works as well on the trails as it looks.


Nice clean look

Lots of chain clearance- ~ 13mm

Friday, October 18, 2013

Magicshine Light + GoPro Mounts

I've been experimenting with various 3D printed mounts for my Magicshine lights. The stock mount uses a thick O-ring to wrap around the bar- and during rough off-road rides it tends to rotate around the bar. I've prototyped several clamp designs. None of them worked as well as I'd like- once I have a design that works well I'll post it online. 

In the mean time, after doing last weekend's Fatbike Adventure Ride III, I realized that there are already some really nice helmet mounts for GoPro cameras. Since I wanted to also create an improved helmet mount, it seemed like a great shortcut to making a better mount. It was easy to put together a couple adapters to mount my MagicShine MJ-808 to a GoPro helmet cleat. The adapter uses the LED light's stock 4mm screw to hold it to the light, and the standard GoPro thumbscrews to attach to any standard GoPro mounts.

MagicShine GoPro adapter, Handlebar / High-Rise

"High Rise" Adapter with LED light & GoPro helmet cleat

Side View

High Rise Mounted On Helmet

Zoomed View
My initial mount worked well, but it put the light well above the top of the helmet- sure to get smashed on a low-hanging branch. This mount should work to mount a Magicshine to the GoPro handlebar mount.

"Low Rise" Mount

"Low Rise" Mount

"Low Rise" Mount

I hope to test the new helmet mount this coming week if the weather cooperates. If it works well, I'll probably post the mount on Thingiverse.