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Sunday, October 20, 2013

Building a Seven Axiom SL...and making it fully custom

"The right tool for the job...choosing every part to make the bike fully custom"

I make no secret about the fact that the part of my job that I enjoy the most is building a fully custom bike for a  client from the ground up.  There's something special about choosing each individual part for a specific reason -- making every part go to work and solve some problem for that particular client.  In addition to that, designing a frame where every tube, every joint, and every feature is decided upon based on the client's wants and needs.

It can be hard to see what I mean when talking abstractly about "some client" and "some bike".  So to elucidate better, I'm going to go through a recently built bike and tell you about the bike in detail and what each part "does" for the rider it was built for.

So here is the bike -- a custom-sized Seven Axiom SL with custom raked Seven 5E fork.

A bit about the frame itself:  A fully custom Seven Axiom SL frameset should tick a number of boxes -- 
  • The frame geometry should allow the rider to have their contact points (saddle, pedals and handlebars) in their most comfortable and efficient position.  This is the bare minimum that a custom builder should be doing for their client -- otherwise a stock, off-the-shelf bike would be providing the same benefit, although I'm constantly surprised of the number of new "custom" bikes I see in my studio for bike fitting services, that have suspiciously stock-looking geometry (and an uncomfortable cyclist on them to boot)
    • Needless to say every tube length and angle on a Seven bike that I am involved with designing is agonized over to make sure it will allow my client their best fit now, AND ten years from now (after all, most of us are slowly changing in our fit parameters)
  • Tube selection and butting/layup schedule should be matched to the rider:  Metal bikes (titanium and steel) can be butted -- or have material removed from each tube to make that tube be more flexible or stiff in a given direction.  Starting with the proper tube selection (i.e. a larger rider is going to need tubes with either a greater diameter and/or thicker walls) is key and then the fabricators need to intelligently butt and miter those tubes so they match the rider's size and desired bike characteristics.  Carbon bikes are made differently -- tubes and joints are created by laying uni-directional carbon fabric (think cloth where all the fibers run the same direction) down in particular sequence and pattern.  In a very basic explanation, if a tube has fibers running every direction but one, the tube will be more likely to flex in that direction.
  • Customized fork rake: this is the often over-looked secret weapon for a custom bike.  When done right (and this means meshing perfectly with the frame geometry) the right fork will make the balance and handling of the bike absolutely sublime.  It will respond predictably but effortlessly to its rider making them feel confident and stable at any speed and on any terrain.  Get the fork wrong and you end up with a poorly balanced, ill-fitting bike that doesn't corner well and often has a speed-wobble.
  • Accessories:  These are characteristics or add-ins we can put on a bike to make it do everything the client wants it to do.
    • Does the client do long rides and not like to wear a hydration pack?  Then three or more water bottle mounts may be necessary.  
    • Are they a bigger rider that lives in very mountainous area?  Disc brakes may make descending safer and more confidence-inspiring (yep, even on a road bike)
    • Do they want to travel all over the world with their bike?  Then S&S couplers, that allow the bike to break into two pieces and fit in an airline-approved suitcase, may be the ticket
    • This client thought she might do some light touring at some point in the future, so we put rack mounts on the frame -- they don't add much weight, nor do they get in the way so why not?
Simple little upper rack mounts above the brakes

On to the wheels......they're Stan's No Tubes Alpha 340 series, tubeless ready wheels with Hutchinson Intensive tubeless tires.

Why we used them:  The area this client rides in  -- western Colorado -- has a lot of thorns (the most troublesome are "goatheads" that spring from roadside weeds) and while it's not uncommon for riders to go  through long periods of flat-free existence, equally common are horrendous rides with 3 or 4 flat tires in the span of 10 miles.  The Stan's No Tubes tubeless wheelsets are great for their flat resistance -- my No Tubes mountain setups have been flat free for many months -- but I've not found the road wheels to be the most stout, so I think their most effective use is under riders that don't tip the scale over about 160 pounds.  My client was a good three to four dozen pounds under this threshold, though, so I knew they would work well.

Handlebars:  In this case we went with FSA Wing Pro Compact.  

Why we used it:  This is a great little handlebar for little hands.  Also, it has a decent flattened section on the tops which, when oriented right, provide a lot of hand positions.  I recommend this bar often when smaller riders want some shape to their bar, but don't want to spend an extra $300 on a set of ENVEs or 3Ts (my two favorite high dollar bars -- because they're strong and comfortable and really take full advantage of carbon as a material.  Many carbon bars end up having little weight savings or ride-quality improvement over a well made aluminum bar because of the way they're laid up).

Grouppo:  Shimano Ultegra (10 speed)

Why we used it:  11 speed wasn't yet available when this bike went into production, and given the option we probably would have gone with it, but it wasn't, so there.  This client test rode some Shimano and SRAM equipped bikes I loaned her and preferred the feel of the two lever shifting system on the Shimano.  Even though the SRAM is lighter, she just didn't fall in love with the Double-Tap system of the SRAM -- just personal preference; nothing more.

We went with 170mm cranks -- she is a smaller rider and according to her bike fit, among the readily available crank lengths, this length proved to be most efficient.  Is this the most efficient length for her?  Potentially....I know, not a resounding endorsement, but until crankarm selection becomes common from ~150 mm to ~210 mm (without spending a fortune) we have to make do with what we have.  Not everyone is ready to pay $800+ for custom crank arms.

The gearing included a compact front chainring and an 11-28 cassette in back.  This was nearly identical to the gearing she had on her old bike.  But an interesting thing happened.  Once we built the bike and she rode it for a few weeks, she found that the compact crankset no longer felt right.  She felt like she wanted more gear nearly all the time.  She wasn't particularly well-balanced on her old bike, which was a main reason for her going custom (and this tends to be very common especially among my clients that are under 5'4" -- it can be exceptionally difficult to find a bike that provides the proper fit coordinates as well as balances the client's weight appropriately over the bike) and once we did build a bespoke frameset for her, and then outiftted it with parts that would nail her fit coordinates AND compliment her riding style, she simply rode stronger and more efficiently.  This was not the first time this has happened, and one unfortunate side-effect was the need for a new crankset.  Certainly not a cheap part, so I got her the standard crankset at a severe discount.  She decided to keep the compact crankset on hand in case she had a really long tour or race rather than have me sell it for her and deduct further from her cost on the new one.  

This is probably the hardest customization to predict -- when an improvement in bike fit will create a need to "gear up".  Also, it can be a tough sell -- imagine telling a client "No I think you're going to want to change the gearing you've had for years because the new custom bike will immediately make you more powerful and efficient" -- sounds a bit too much like a sales line.  If the new bike is going to be built for a different task -- like touring -- then it's relatively easy to recommend a gearing change, but predicting the degree of benefit someone gets from a custom build is a bit like reading tea leaves, because it can't be easily or effectively tested without being on the custom frame already.

Seatpost:  Seven custom titanium setback post

Why we used it:  A titanium post can work wonders on the comfort and ride feel of any bike, no matter what material the bike is made of.  BUT, in my experience, you'll get a lot more out of it, if you have a decent length of seatpost sticking out of the frame.  About 6 inches (~15.25 cm) of seatpost from the saddle rail clamp down to the top of the seat tube is a reasonable starting point.  Less than that and you likely won't get the nice compliance the titanium provides.  

When this bike was first designed, it became clear that given her optimal saddle height we would have at least this amount so we went ahead with the Ti post.

If we hadn't had enough post length could we have modified the geometry of the frame to for more post?  Well, we did modify the geometry to account for the setback nature of the post, but modifying a frame design for more seatpost length will affect the standover, the top tube slope (which in turn changes how the head tube is welded or molded into the bike), and will affect how water bottles fit inside the frame.  Not insurmountable problems, but ones that could be greater than just not having a titanium post.

A few notes:  

-- in the pictures, you may notice that we have 3cm of (titanium) spacers under the stem and a couple mm of spacers on top.  I usually start a client a bit higher in their position and then we slowly lower them into position over the course of their follow up fit appointments.  I've found it's a much smoother process when we start high and work our way down with bar position.  Will we always need those spacers?  Perhaps not, but if we don't we can always cut more steerer off later and remove some spacers -- can't add them back if we cut too much the first time.  It's typical for me, and should be "best practice" at every bike shop, to start with as long a steerer as allowed at first.

-- the clamp on the Seven seatpost is great.  It has two bolts on the head: loosen one and you can control saddle fore/aft, loosen the other and you can control tilt.  The adjustments are independent of one another, which makes fine tuning saddle fit a breeze.

So that's the long and short of it.  Many hundreds of tiny decisions, all having to be made with rider fit and efficiency kept in mind all the while

1 comment:

  1. The material and aggregation is excellent and telltale as comfortably.