The Golden Wrench

A blog about bicycle repair and maintenance by the mechanics at Freewheel Bike.

Monday, January 28, 2013

Lefty Max upgrades

This comes up a lot here at Shockspital: a Lefty Max comes in for service that still has the old Manitou damper in it. These are cool forks because they use the same chassis as other Leftys, but the damper is where the air spring would otherwise be and there's a big coil spring in the top half of the fork. The damper is also a lot simpler than a DLR/PBR/XLR Lefty, relying on a single shaft seal to keep the oil where it's supposed to be.

But, you guessed it--Cannondale doesn't make parts for these anymore. So if the damper shaft gets damaged, the fork becomes a very good candidate for a damper upgrade, including the new air spring system that modern Leftys use. This upgrade has a ton of benefits, not the least of which is the weight savings!

At top in the above photo is the stock coil spring from a 2004-2005 Lefty Max SPV/TPC. At bottom is the RockShox-produced Solo Air spring assembly which replaces it as part of a PBR/XLR damper upgrade on this fork. The coil weighs in at 256g. The air spring assembly is 39g (including the packaging!).

Weight weenies, rejoice!

Tuesday, January 22, 2013

The March of Progress

I remember when mountain bike manufacturers wisely started to put straight-bladed rigid forks on their mountain bikes. It was an adorable little trend started by some well-meaning folks with names that rhymed with Richard Cunningham. Yep, feel all that steering precision! Lighter weight? Sign me up! Then you ride the front wheel over anything taller than a nickel with the obligatory 50 PSI in the tires, and next thing you know you're being fitted for dentures. Straight-bladed forks were awesome!

Then this hoser named Paul Turner came along and tried to single-handedly sissify the sport of mountain biking forever by hanging an air-sprung, oil-damped, slurping monstrosity off the front. Suspension: 48mm of sticky, slurpy suspension. That 48mm number was theoretical: the only way you would see that is if you hit a railroad track stiff-armed at about 20 mph. Sure, the RS1 was flexy, leaky, and primitive, and it didn't last too long; but it changed the landscape forever. It made you faster over rough terrain because it kept you in control. "Control" was more-or-less responsible for the mountain bike boom of the mid-90's.

"Yeah, the front tire sticks to the ground in corners. Pfffft. But you dress funny, mister booger britches," hissed the purist opposition through their dentures.

The suspension thing more or less took off. Then, one day, Rock Shox turned into a big ole company and Paul Turner went and did it all over again.

He started a company known as Maverick. Their Mono-Link rear end was kind of weird, and rode like a GT I-drive with less stiction. But it sort of works if you like to just lean back and slam stuff with your back wheel, and some people really like it. Maverick also made a couple of inverted forks: the SC-32 (single crown) and the DUC-32 (double crown). Both were light and plush, but the SC-32 was known for being a tad on the flexy side. Maybe more than a tad: sometimes, if you really honked on the front brake, your front tire would swing back rub your down tube. But it was light and plush, and times were simpler then.

Maverick forks also required a hub with a proprietary 24mm axle to prevent independent leg movement and lateral wheel flop. It works pretty well, but there's that pesky word "proprietary." Now's a good time for a life lesson for all of you tinkerers out there with aspirations for inventing the next big thing: if your product requires a proprietary means to attach to a bicycle and your last name is not Shimano or something like that, plan to be hated. It's the way of things.

The SC-32 fizzled on XC bikes because of the flex and the front axle. It went out of production a few years ago. End of story?

Not even almost the end of the story! A fat bike tire fits through the fork with just enough clearance. The flex really doesn't matter on a fat bike: is mitigated by the weight of the wheel. This is a hot setup when old snow packs down to frozen stutters. Kind of like January in Minnesota, when it's ten miles below zero after a week where half the snow melted. Can you say "frozen hiker tracks?" Mix in some Grip Studs and you're ready to take on the choppiest trail!

Is suspension for everybody? In 1991 I said "no way." Today, I say "probably not." But it turned out that suspension was just the ticket for about 95% of riders on the dirt. Will the snow experience such a revolution? Who can say?

But I have to admit, that looks like a lot of fun.

Monday, January 14, 2013

DIY Grip stud install

Well it's that time again, to think about studding tires for the fatbike.  We here at Freewheel Bike have been using Grip Studs for this need.  They work in most of the fatbike tires that are on the market.  So here we go.
Tool and studs needed for install

The tires I picked for this project were a Surly Larry and a Surly Nate.  Both of these tires offer a great tread block to screw the stud into.

 The first step is picking a pattern for how your studs will look on the tire.  I use a silver Sharpie to mark the location of my studs.  After you have your pattern, you are now ready to screw some studs in the tires.  I like the hand tool over the tool that works in the electric drill.  I have more control installing the stud with the hand tool.  When working on 45nth Escalator tires that have the holes predrilled, that is when I would use the electric drill tool.  So you start by loading a stud into the tool of choice.  With the hand tool, press the stud firmly into the meat of the tread and start to screw the stud in.  The studs are self tapping and will bite into the tread to start themselves.  Screw the stud down to the shoulder of the stud so it is touching the top of the tread.  I will give it another 1/8 of a turn to make sure it's where I want it to be.  Continue in this manner till you have all your studs in place.  Some tires like the Larry that I studded, take a little more time to stud up.  With little area to get the stud started it makes it tougher and more time consuming.  But with some patience, you will end up with a great looking and working tire.

 As you can see, I have a few studs installed and we are on our way to having some studded tires.

 This is a view of the tire with the studs in place.

 It takes about an hour to install 100 studs.  This front Larry ended up having 125 studs installed and the Nate has 76 studs installed.  For the Nate, I installed the studs down the center tread for traction and the Larry has studs in the center and on the sides for cornering traction.  This seems to be a good balance for the types of terrain I'll be riding or racing.

 In this picture we have a fully studded tire going out for a test ride to the local ice rink near my house.  The tire hooked up well on the ice and I felt that the pattern I installed was just what I needed to help stay upright.

I got my chance to try these tires out at a local race that Freewheel Bike puts on and they were the ticket.  The course was very icy since we had rain prior to the event.  I made the call to use these and I'm sure glad I did.  The course looked more like a bobsled run than a bike trail and the tires and studs I had on the bike sure made all the difference in me making it out alive!  I had to get used to the drifting the tire would do on the ice, but once I got this feeling under control and trusted that it would find traction, I was riding like I do on a dry trail.  The drifting was not out of control, it's just the tire searching for it's traction so I can keep putting power to the pedals and moving forward.

So for those thinking that they want to try this at home for upcoming races like the Lake Minnetonka Ice Race or any race that will be on ice or trail that is icy, you should run out and pick up some Grip Studs and get busy with some tires.

Thursday, January 3, 2013

DT Swiss star ratchet magic

How do you double the awesomeness of the already-awesome DT Swiss star ratchet freehub mechanism? Start with a stock DT Swiss hub...

...then  acquire a set of the 36t ratchets (below right; compare to the stock 18t ratchet)...

...then simply pull the end cap and freehub body off the hub shell (no tools required, no pawl springs to catch as it comes apart), drop the 18t tooth ratchets out, slide the 36t on, and pop everything back together.

And bingo! Just 30 seconds after you started, your DT hub has double the engagement and half the rotational dead space for faster hook-up when you get on the gas. Oh, but don't forget to flip the two coil springs around--the new ratchets are machined out in the center and the narrow end of the spring tends to slip into that empty space.