Tuesday, August 3, 2010

Rocklobster Custom Single Speed

At some point I came to the conclusion I wanted a custom made bike. Living in Santa Cruz I had several choices and decided on Paul Sadoff and Rocklobster. Paul has been wielding bikes for over 20 years and may have been the first to wield a singlespeed specific frame. The time was early 2002 and Eccentric Bottom Brackets (EBB) were the rave; it’s still probably the most elegant solution to tensioning the chain on a single speed. When Paul asked what I wanted, besides the EBB, I liken to my Bontrager. Interestingly enough when Bontrager closed up shop in Santa Cruz, Paul bought a good deal of Bontrager Cycles True Temper steel tubing and sub-assemblies, and used the tubing to build frames that were referred to as Nontragers. Well, Paul had long ago ran out of the old Bontrager tubing, but still had a quantity of Tange tubes that was certainly equal in quality. I explained to Paul that I had bought a Marzocchi Atom 100 for the bike, so I wanted something like a Bontrager, only a larger sized, designed for the 4 inch fork I bought, a more relaxed head tube, and disc tabs in the event I decided to use disc brakes. Paul also included Bontrager brake bosses, which use a bolt and bushing that screw in from the top all the way into the frame, rather than a standard boss stud and retaining screw. I was also a big fan of straight handlebars and bar ends at the time. For about $50 he also threw in a steel stem. The photo above is a comparison of my Rocklobster bike and a Bontrager Racelight; the seatposts angles and forks seem identical.

There is nothing more ridiculous than having a brand new bike. The paint is perfect, without a scratch, and you for some reason try and keep it that way. Finally you get a couple of scratches and finally being as imperfect as you, it becomes your friend. In my case I dug a pedal into the side of a hill and the crank arm dented the chain stay; damn. I have gone through so many wheelsets I had to look back at old pictures to remember the what came first. From what I can tell, the first wheelset I bought was a Surly/ Mavic; thinking I would never used disc brakes. I then bought a set of Deore hydraulic brakes and a $75 Shimano Deore/ Alex disc wheelset (the photo below is my first ride with the disc brakes) . Thinking I needed to upgrade to a singlespeed wheelset, I disassembled the front Surly and laced the rim to an Real disc hub and tried using a screw on disc adapter on the rear Surly hub. I suspect the adapter did not hold the disc perfectly straight, as it would squeal when it got hot. To solve this problem I disassembled the rear Surly wheel and laced the rim to a Novatec singlespeed hub. This worked very well about a year until the cartridge bearings (4 of them) wore out. I then weighed the Novatec rear wheel and found it was actually heavier than the Deore/Alex rear wheel and also came to the conclusion I would no longer deal with Singlespeed specific rear hubs anymore, unless I came up with a purpose for the Surly hub, which I did when I later built up my Bontrager reconstruction project 1993 Bontrager Single Speed. It just seemed that the singlespeed hubs where more trouble than they are worth and opened up the ability to buy a better wheelset, like I did with my SASS build, SASS Meets 650b . While technically a singlespeed wheel has less dish and is therefore laterally stronger, I don’t see wheels on geared biked failing, so in the real world it’s simply not an issue.

I have never second guessed my choice of the Marzocchi Atom 100 and still consider it to be one of the best riding shocks ever made, The Atom 100 is the last race shock Marzocchi made with dual steel springs; the newer forks have only one steel spring or no steel springs at all. For me there is simply no substitute for steel springs, and while the Atom 100 is certainly heavier than the single steel spring or air spring, it gives a ride that only a steel spring can give. Interestingly enough, much of the valving and R&D of todays forks is to simulate the feel of steel springs.

One thing I have not discussed is my use of suspension seatposts. This started with my privateer, and worked well taking the edge off the hardtails I was riding. The post I used was a USE, which is one of the lighter of the suspension posts. The USE posts use elastomers and a spring and have about 10 mm of suspension. When Bontrager stopped making their classic squared off seat, I switched to older style Selle Italia, which of course they have also stopped making also. Last year however, after using my suspension seatpost for the stoker seat on my tandem, I found a good deal on a Thompson seatpost and found I have not missed the suspension post in the least.

The last issue with my Rocklobster is the handlebar. The bar I originally spec’d on the bike was a Bontrager Racelite 680 straight bar with bar ends. There is still no better setup for climbing. But like everyone who rides long enough, I started experimenting with different bars. Originally I switched to a Misfit Psycles FuBar. The folks at Misfit Psycles read a posting I had on MTBR.com and offered a handlebar if I would use it and write an opinion on it. Misfit Psycles FuBar Well it turned out to be a pretty good bar, but I never did like the sweep of the bar, which necessitated a 150mm stem. The long stem made my hand position fairly comfortable, but it destabilized the front end and climbing was more difficult; still I rode with the bar for about a year. My current bar is the Titec H-Bar, which is a licensed copy of the Jones H-bar. This bar allowed me to return to my 120mm Rocklobster stem and brought my hand position farther forward, making climbing much easier. It’s no Bonty 680, but I like it much more than the FuBar. The next handlebar I may go with is the Groovy Luv Handles. They are similar to the Jones straight tube ti H-bar, but with less sweep. Apparently they only come in steel or ti; the steel bar has been desbribed as punishing and the ti is $250.

This bike has been my go to and comeback to bike for 8 years. It’s comfortable and of course made just for me. At some point after you have been riding you really should get a custom built bike. I highly recommend Paul and Rocklobster; he’s been making frames longer than most and has a reputation for making a very high quality product for very reasonable prices. Yes, he rocks! And so does my bike.

Monday, August 2, 2010

My Road to Singlespeed

My single speed craziness started with a Bontrager Privateer and a Jamis Dakar. I bought the Privateer in 1998 and was satisfied with the Trek version of Keith’s classic bicycle, which I still own today; see the photo on the left. If I had to do it again I would probably would have gone with a larger frame over the medium I bought, as Bontragers run small. Although I bought the “S” Sport level, I upgraded the hubs, shifters and cranks to XT, resulting in a XT gruppo with Avid brakes. The original shock was a Rock Shox T2; an elastomer version of a Judy XC, that is upgradeable with cartridge kit to the equivalent of the Judy. After attempting such an upgrade, I blew out the cartridges at a rate of 1 a month, so I replaced it with a Marzocchi Super Fly. The T2 shock also had a special Bontrager designed crown with steeper geometry. The Marzocchi upgrade stabilized the ride not only because it’s a stronger shock, the more relaxed geometry with a standard crown really calmed down the steering. This was made possible as the 1998 (and 1999) were the only Bontrager frames made with a 1 1/8” head tube. The picture here is the current condition of my Privateer. With the exception of the King headset, shorter stem (As I said before Bontrager’s run small, so with the smaller stem it can be setup closer to a small frame size; I did this for my wife), seatpost, pedals (I still have the originals) and front rim (I taco’ed the original), the bike is the same build I bought in 1998.

Well after happily riding my Privateer for 3 years, I decided to go with a dual suspension bike and bought a 1996 Jamis Dakar frame from Supergo.com (later bought by Performance) and built it up. The pictured bike has the same frame with a slightly different (but surprisingly similar) build; imagine this bike with a red Marzocchi Atom 80 fork. Well this left my Bontrager just hanging in the garage, so I figured I’d check out this single speed thing.

My first foray was to buy a Surly Singleater, TruVativ Stylo single speed crank and a spacer kit. I started with a 32:16 gear ratio with the Singleator in the push down mode. I then bought a Surly SS rear wheel from Sheldon Brown and ran it with a 16T and 18T freewheels. For some reason this caused the chain to skip at the rear (16T) freewheel. The reason is as follows,

The usual suspect of a skipping chain is a spring loaded tensioner. Most spring tensioners work by pushing the chain down and away from the rear cog. This results in very poor chain wrap. When peddling the majority of the torque from the chain is on the front chainring is on the teeth at 12:00 –0300 and on the rear cog it is the teeth from 6:00- 9:00. What this means is the very area of the rear cog where, chain wrap is necessary, a push down spring tensioner pulls the chain off the cog. This transfers the torque to the tensioner pulley wheel, which in turn pulls the tensioner arm upward. The chain then rides up in the cog teeth in the 9:00-12:00 position. Since it takes a great deal of torque to turn the rear wheel and there is practically no chain warp in the area, the tensioner will fail and the chain will jump over the teeth at the 9:00-12:00 position on the cog, causing it to “skip”. The answer is to first make sure your chain is as short as possible (a half link is a good idea but it will create a weaker link). Next use a spring tensioner with a push up mode or even better a tensioner without a spring so the arm can be locked up; this way tensioner cannot be defeated by overcoming the spring tension. A quick fix is to zip-tie the tensioner arm to the chain stay. This will create a tensioner in a push up mode that does not rely on spring tension. This is a photo I set up to show how such a setup would look.

When this first happened I was in the middle of a ride. I switched to the 18T freewheel (with a 32T chainring) which turned out to be the so-called “magic gear”, or a setup where the chain does not need a tensioner with vertical dropouts. I then figured out that with a half link, the same was true with a 16T freewheel. At some point later I sold the Surly wheel and bought a Spot wheelset that I really didn’t like and I ended up selling it, and returning to a spaced rear wheel. I have only one picture (of poor quality) of this Bontrager as a single speed I took on a Soquel Demonstration Forest ride. This is the bike I rode until I has custom bike made for me by Rocklobster in 2002.

Next: The Custom Bike