Farnsworth Engineering

Bikes fall into categories based on a lot of factors.

A “tour” bike is built for long days and often a mix of riding and camping.  The bike has low gears and mellow handling because it is not about racing but rather simply about enjoying the day.

When I grew up my first serious bike was a loaded “touring” bike. It was a nicely built classic touring bike from Japan sold under the Bridgestone brand.

My Dad and I did many long rides including trips to Sugarloaf mountain, the Skyland drive, Amish country, Williamsburg, and many other great places.

The bike served me well for many years and my dad also later spent some time riding it. Overall it was a good bike but the design had problems.

It was almost 30 years ago but I think the bike was a Bridgestone T-500 similar to the following:
http://sheldonbrown.com/bridgestone/1985/pages/18-bridgestone-t-500.html

Starting with the good stuff that I remember about the bike:

• Classic stable handling with the low bottom bracket height, relaxed angles, and long chain stays
• Good brakes for the era (cantilever design)
• Wide range 15 speed drivetrain
• Comfortable bars, saddle, and overall riding position
• Decent quality in all parts

The stuff that was not so good was often related to the era.  It was about 30 years ago and bikes have moved forward.

• The headset and stem design sucked; modern 1.125 threadless systems are a world better
• Shifting was not great
• The the wrap style style seat stays attachment was a bad design.  You can see them in the catalog photo.  The stays eventually cracked where they “wrap” onto the seat tube.  Modern TIG welded joints are much a much better approach.  The tubing on these old bikes was also smaller diameter thick wall vs. the larger diameter thin wall high strength steel used on modern bikes.
• The top tube was a bit high and stand over height was not great.
• Cable guides on the top of the top tube (I prefer under the top tube)
• The cranks creaked and even fell off once (modern cranks are much better)
• I was still growing when we got it and the bike never really fit perfectly

Don’t get me wrong, I loved the bike, it was great and my Dad gave it to me.  I very much enjoyed the bike and often think back on great rides that I did with my dad.  The Bridgestone was my first “real” bike and I will always be thankful that he took the time to ride with me.

After I got my first “racing” bike my Dad started riding the Bridgestone.  Eventually the Bridgestone cracked and had to be replaced.  After the old bridgestone cracked he replaced it with a nice TIG welded Cannondale.

The Cannondale tour bike was a really nice model similar to the following.

My Dad still rides.  The Cannondale is at least 20 years old now.  He is ready for a new bike.  I want to build him something nice.  The bike needs to ride a lot like the Cannondale but with modern component updates and refined style.  The functional geometry that Cannondale used for their bikes worked well for general touring and pleasure riding.  They actually kept the geometry basically the same for many years because in terms of “classic” touring it is best to go with what works.

When I think about a tour style bike today, I imagine  modern technology focused on general relaxed riding.

Change that come to mind are:

• tig welding (duh)
• mountain bike inspired sloping top tube ( the bike will ride the same as a a horizontal top tube but using a sloping top tube will give better stand over height )
• 1.125 threadless headset, stem
• indexed shifting with 20 gears
• better brakes with modern disk and maybe hydraulic
• better wheels with improved bearings
• everything lighter, stronger, and more durable
• A mix of mountain bike and road components to support a wide range of gears
• better fit…

The following is a vague picture of what I think a modern touring bike should look like.  This bike is inspired by the co-motion pangea.   The 26″ wheels look a little funny but they make a lot of sense for a touring bike because they save weight, allow a lower top tube, plus they are stronger and lighter than larger wheels.

A sloping top tube makes sense because after a long day of riding it is a little easier to swing your leg over a bike that has a lower top tube.  On the front end, the bars need to be high enough for a relaxed position.

Every line is drawn…..

And later every line is fabricated….

I live in the city of Raleigh but am super luckly that my house is only two miles from Umstead park where we have really nice fire roads.

My wife and I had a fun little trail ride today. Near the end of the ride, she was asking me about log crossing technique. We did this little video clip showing the basics. My technique still sorta sucks but I have improved from where I was last year.

I would like to say short chainstays and proper bottom bracket height is critical but in truth “it’s not about the bike”. Technique trumps everything.

The key thing that I have learned is to focus on confidence. Simply hold to the belief that if you get your front wheel over the apex of the log the rest of the bike will follow. A little bit of speed helps but you don’t want to go too fast. The final bit is keeping your weight back so you don’t stack up on the way down the log.

For lofting the front wheel the best approach is to slightly pull up on the bars and at the same time apply pressure to the pedals to in effect power wheelie. With the front wheel up, you can bash the chainring into the log. If you time the crank phase and add a slight “bronco” you can cross some pretty big logs.

What about you guys, do you have an tips or techniques.

Once a year there is the big NAHBS show for handbuilt bicycles. I did not go to the show but have enjoyed looking at the photos on the internet. The NABS site has tons of great photos and other websites like Velonews, CyclingNews, Bike Rumor have additional photo galleries.

My favorite bike from the show was from Groovy Cycle Works. The Groovy bikes are always great and the paint takes things to the next level. I liked this one mostly because it is green.

The bike shows are great for the art and craft of bicycle building. For 2014, the show comes to Charlotte, NC. I plan to go to the show next year to checkout the crazy bikes in person.

I am making some modifications to my Henry James JIG.

In particular, I am obsessed with making the rear end of the next bike perfect.

On a 29er single speed, chainstays are what gives the bike it’s life.  Stiff chainstays give you great power transfer and improve the handling.  Tire clearance with short chainstays adds to the challenge and to top things off many riders have issues with heel clearance.  More then any other area the chainstays are where you fight to go from good to perfect.

On my current bike things are “good” with nice short stays but I can only run a maximum of 2.1 rear tire and I dimpled the rear end just about as far as possible.

My plan for the next bike is to step up to 22mm round chainstays to improve lateral stiffness and at the same time give the bike more theoretically vertical compliance. I am also planing to run 2.35″ tires with room for a good bit of mud and the occasional broken spoke.

Since I want my bike to be strong and keep all the stiffness from the stays I plan to only have a very minimal dimple in the drive side chainstay.  The dimple will be small and placed exactly where it is needed to allow the chainring to clear the stay.  This approach provides better stiffness and strength as compared with crushing both stays because the non-drive stay will have it’s full cross section and the drive stay will have 18mm cross section in the dimple area and 22mm cross section in all other areas.

The other bit that makes the plan work is good “S” style bending to snake the chainstay around the tire and provide heel clearance for duck footed pedaling.  The chainstay needs to allow a 160mm rear rotor and will have a small crimp to allow the chainring to be really close to the rotor area.

The final bit will be 142×12 through axle dropouts and a PF30 bottom bracket shell up front.  The bike will run an eccentric for chain length adjustment.  The throw of the eccentric throw will be forward only.  The bike will “magic gear” for 36×22 at 90 degrees with a brand new chain. There will be plenty of throw for any gear I want but since I ride 36×22 most of the time I want everything to be 100% optimized for that one.

For all this to work the layout needs to be 100% spot on and alignment of all components is critical.

Special bits for the jig assist me in layout. The dummy crank spider helps me position the drive side chainstay exactly where it should go. The plate ensures that the “S” bend stays are in perfect phase. The little mounting block for the plate doubles as a reference for the area that I need to reserve for the brake rotor.

The chainstays are still a bit long.  I still need to finish machining some more bits for the JIG then later on I can cut the miters on the chainstays and position everything for welding.

I still plan to make a dummy cog holder and a few other bits so I can dial things and “magic gear” check things.

My commute to work includes a little bit of bandit single track.  One of the parts that I really enjoy is a short steep little technical climb.  The trail has roots, rocks, holes, and little washed out sections.

This morning, I was powering through the area with a good bit if speed to “attack” the start of the steep section.

As is often the case the crash was sudden with my front wheel abruptly dropping into a hole.  My weight shifted forward and then I felt a crack and found myself going over the bars.

It looks like the left bar end gave way under the stress just before I went down.

The good news is that I was relatively unhurt with only slight stiffness in my wrist.  Other then the broken bar end the bike seemed fine on the rest of the ride to work and the ride home.

Today, I started my preparations for the 2013 race season.

I am anti-doping to level the playing field.

All season long I will have this kick ass excuse for every time I suck at races.

Yes, you guessed it, I gave blood at the Red Cross Blood drive.  If you are faster then me you should give two pints at your local blood drive.

I am still a huge fan of the monster drivetrain that my friend Terry made for me.

Yes, it is huge!

Yes, it is heavy!

Yes, it is overkill!

But it puts a smile on my face each time I ride and does not look like it will wear out any time soon.

Recently I made a tweak the the way the cog is mounted.  My favorite rear wheel setup is Paul Components WORD.  I now have a modified white industries freewheel with five stainless steel bolts to mount up the monster.  The White Industries freewheel is the gold standard for durability.  This setup is rock solid and seems totally bomb proof.

Happy trails!

I got some new bike bits in the mail today from Paragon Machine works.

I am planning “S” bend stays, press fit 30 bottom bracket format, 44mm head tube, and through axle dropouts. These bits support some relatively new standards for mountain bikes and it will be interesting to give them a try on the next build.

The press fit 30 bottom bracket shell and 44mm head tube look like the best of several competing new standards. These standards reflect the movement towards forks with tapered steering tubes and cranks that use oversize hollow spindles. The bike industry continues to evolve and these new formats give riders more choices. In the context of single speed I am also excited about the idea of running an eccentric bottom bracket using the PF30 shell.

In particular I am looking forward to working with the special through axle dropouts. On a mountain bike, I want a totally solid connection with the wheels. The new axle format ensures that the wheel will never shift in the dropout and will always be in perfect alignment when installed with no second guessing or checking to see if the wheel shifted after a crash or rocky decent.

My new tube bender.

In Raleigh we almost never get any real snow.

I like snow but all we got was a little bit of dust.

Our winter is like summer in Canada; Last June, I was in Canada pushing my bike through deep snow.

I am planning some “S” bend chain and seat stays that I hope to make. I want to custom bend my own stays to gain more control over the process and learn about bending materials. Using “S” bend style stays helps provide clearance for big tires and prevents the riders heals from rubbing on the chainstay.

Custom bending with 7/8″ chainstays and 5/8″ seat stays should also produce a totally awesome ride. Based on the CAD design it should be possible to run 2.35″ tires and still have a super stiff drive train with enhanced lateral rigidity and tuned vertical compliance. I am also designing around features like a 142×12 through axle, eccentric based bottom bracket, and 44mm head tube.

To work out the specifications for bending the stays I did some 3D CAD drawings to sort out issues. I am not into bending for “artistic” designs. My goal is to optimize ride performance, fit, and tire clearance. I am a big fan of allowing the form to follow the functional requirements.

Cable guides, TIG brazing using Silicon Bronze.

The hose clamp helps with setup for tacking the guide in place. For brazing I use a bit of aluminum foil to help keep the shielding gas in place. The process requires a delicate touch because the Si/Bronze melts at a fairly low temp and does not flow very well. The reason I use Si/Bronze is that it puts much less heat stress on the tubing vs. true welding.

The difference between “welding” and “brazing” is that when welding the metal of the part you are working on melts and mixes with the metal you add. With brazing the metal you add melts but the metal of the part you are working on does not melt. Brazing allows the tube to maintain most of it’s original strength. The cable guide is in effect glued on using a bronze alloy.

Little details make all the difference….

I got my new Henry James frame jig and the fancy jig stand setup last weekend.

Overall the build quality for the JIG is outstanding. Everything is bright and shinny. Geometry setup is super fast and direct. It looks like it will be a good tool for my shop.

I will provide some follow up after I complete the next frame.

I enjoy having one really long ride each week and Sunday seems to be best day.

For the first three hours I did a moderate pace and simply enjoyed spending time in the the woods on my bike.

In fourth hour, I did some harder intervals on one of the more challenging trails. For the last two hours I joined the Natty Greene’s Southern Sunday Ride. I was parbaked at the start of the ride but riding with a group was fun and helped give me energy.

If you ride Raleigh area trails you can likely guess some of the tails I road based on these photos.

I am hard on my bike…

On my way to work on Monday, I bent my rim.

The repair only took a few minutes with a big pair of pliers. The rim is not as good as new but it works. It will be interesting to see how it holds up.