Titanium WiseCracker LITE Bottle Opener

We're teaming up with Paragon Machine Works to produce a very limited run of titanium WiseCracker LITE bottle openers for the holidays. These will be sized to fit any 1-1/8" steer tube and will come with a lightly polished finish.

Price will be set at $35 per unit including domestic shipping. Send an email to 'mike at ahrensbicycles dot com' to pre-order yours today!

SF Bike Expo

Great day yesterday at the SF Bike Expo at the Cow Palace and special thanks to my sister Elizabeth for helping out. Our booth was right across from the indoor dirt track used for the 'cross races. We brought three bikes to the event....a white monster 'cross frame, red 650b hardtail and gray urban 'cross bike. Customer turnout was good and we will surely do it again next year!

More Pics of Kristy's SS

Here are some more in process photos of Kristy's single speed hardtail. The head tube rings are machined on the front side of the tube only....this leaves more material on the back side of the tube for strength. Machining rings into head tubes is common across the industry...but machining eccentric (off-center) rings is more difficult and is rarely seen on production frames.

Small vent holes inside the frame allow the inside tube surfaces to be purged with nitrogen; this gas runs through the red flexible tubing which is attached to the welding fixture. This means no impurities will be present after welding which is important since inspecting inside the frame is nearly impossible with conventional tools. Prior to welding, all key joint surfaces are thoroughly cleaned and deburred.

The Easton Ultralite 'pear shaped' down tube is bi-ovalized for strength and maximum weld area at the head tube and BB shell. This tube is so tall it accounts for more than half the real estate of the head tube! As a result, the top tube receives an interference cut to 'cup' the down tube and head tube for the ideal mating fit. The top tube is also bi-ovalized to maximize joint strength at either end.

The rear triangle components are pre-assembled ahead of time in a special fixture designed by Anvil and then integrated into the main Anvil fixture to create a complete frame. The rear dropouts are spaced slightly wide at 137mm to account for slight spring-back which can happen when welding bike frames. In this case, the spring back is minimal due to the shape and rigidity of the upper/lower yoke components.

During fabrication, the sliding dropouts are positioned all the way forward which translates into a 16.5" chainstay length (measured center-to-center). Once the bike is assembled, the sliders will be re-positioned between 16.5-17.2" depending on the desired riding characteristics. I usually set this distance to ~16.8" to strike a balance between climbing and descending ability. Too short and the bike will be unruly during high-speed descents. Too long and climbing response is reduced. Since the dropouts can slide, it's very easy for the end user to dial in their ideal chainstay length on their home turf.

When working with aluminum, material availability can become an issue since it's imported in very small quantities to the USA. As a result, I've started to develop frames using round rear stays (in lieu of rectangular tubes) that are hand-formed for the ideal fit before welding. In this case, the chainstays are 25mm round and then swaged near the dropout joint. The seatstays are 22mm diameter tubes with similar treatment as the chainstays. The ride quality of the round tubes is excellent and on par with the classic rectangular stays used up to this point.

I expect this frame to weigh in under 3.6 lbs which should provide an excellent platform for single speeding!

Happy Friday

First email I read this morning.....

Received my Wise Cracker and it’s ready to go!

Looks awesome and works great!

The El Mariachi is a “complete” bike now.

Thanks, Bill

Belt Drive Dropout Conversion

Here are some pics of a belt drive dropout conversion created by frame builder Chris Kopp. The dropouts are split in the seatstay zone and then attached back together with a simple backing plate. Looking forward to seeing the completed frame...

Current Projects

I have quite a few frames in the queue right now and I'm excited that business has been picking up this quarter. This year has been slower than normal due to the economy and it's nice to attract some new customers!

Since my wife's bike was recently stolen, we decided to replace it with a step-thru, single speed townie frame. This frame will be outfitted with a Shimano Alfine drivetrain, dual disc brakes and fat 26" city tires. We also plan to install a front basket for quick trips around the neighborhood.


Next up is another single speed mountain frame for Kristy in the mid-west. This is a smaller frame that will be setup with a Fox F32 80mm travel fork, King wheelset and Race Face components...here are pics of the pre-cut tubes before welding the entire frame together.

More pics to follow as these projects (and others) near completion. And if you're in the Bay Area, be sure to stop by our booth at the SF BIKE EXPO next weekend! We'll be selling some old inventory and of course the ever popular WiseCracker bottle opener just in time for the holidaze.

New CX Commuter

I just finished assembling my new commute bike and I can't wait to log some saddle time on this baby. As shown it weighs in at just over 22 lbs with dual disc brakes and mostly MTB drivetrain including XTR shifters and rear derailleur, XT 12-32 cassette and dual-pull front derailleur, and Shimano R600 compact cranks with Race Face 36/46 chain rings.

The front end geometry is setup around a Wound Up CX disc fork and tallish head tube for a more upright body position. The bars are the FSA Metropolis model; basically a modern mustache bar with 31.8mm center diameter. They are flipped over to hit my hands in just the right spot.
Frame geometry is derived from the standard Whole Shot 'cross lineup which has been evolving over the past few years.

The left side/ISO disc dropout is triangulated with a support tube welded between the seatstays and chainstays. Sliding dropouts are used for extra flexibility in case I want to convert this bike to one speed. The front/rear brakes are Hope Mono Minis with Scrub metal matrix rotors.

Special thanks to Paragon for supplying the brass 'jam nuts' used on the sliding dropouts...way better than the standard ones I've been using.

Kenda Kommando cross tires mated to Velocity VXC rims (painted to match the frame) and Sun Flea disc hubs round out the whole package.