Headfirst into the deep end of bike spec.

Headfirst into the deep end of bike spec.

BikeCo.com rider @JCyouKnow dials in his spec for a recent race.

On trail performance of mountain bikes is advertised as a sum of the total components.  That is to say if we assigned a max value of 10 to each component in your cockpit the equation would be:

Handlebar 10 + Stem 10 + Headset spacing 10 + Grips 10 = 40 Total

A handlebar with only 50% capacity for a rider would carry a 5 instead of a 10.

Deficient Handlebar 5 + Stem 10 + Headset spacing 10 + Grips 10 = 35 Total

The hole in the above logic is that all the cockpit components must work in symphony with each other.  Instead of a “SUM” (addition) the total performance rating an improved way to look at it would be the “PRODUCT” (multiplication) of your components – which leads to:

Handlebar 10 x Stem 10 x Headset Spacing 10 x Grips 10 = 10,000

Deficient Handlebar 5 x Stem 10 x Headset Spacing 10 x Grips 10 = 5,000

So with the deficient bar instead of the “Sum” of your performance being  88% the “Product” of your component equation is 50%.   “Almost working” became “no where close” fast.

OK out of our theoretical math and back to why you’re here – your on trail riding experience.

Component spec requires a clear understanding of 1. What deficit you want to address 2. Which parts effect the desired change 3. What interacting components will need to be addressed to avoid a second performance drop.

In order to keep this from being a 100 page thesis let’s work with an example we have all seen, heard, read, had beat into the ground – headtube angle.

As a rider can you pick out the trails which benefit from a slacker headtube?  A steeper headtube?  Are you racing and dialing in for a single run?  Is this a pleasure bike for all conditions?  How sophisticated is the frame manufacturer?  Slacker for slacker’s sake is not the answer to handling – there is much more going on than simply hanging a chopper angle out in front of your bike.

Geometry and suspension considered top notch may benefit in high speed groomed trails with a slacker headtube.  However the slacker headtube angle often hinders performance in low to mid speed and across loose chunky terrain.

Did you work with handlebar rise, handlebar sweep, handlebar width, stem length, stem angle (rise, neutral, drop), stem/headset spacer height, riding position (don’t underestimate the value of Body English riding a mountain bike!) before you decided on headtube angle mods?  A quality resource will review if any of the above will help you find a more confident feeling front end.  The right bar, stem, and height will take a bike from so/so to so good really fast.  Plush suspension, not inefficient – plush, will allow you to slacken the bike temporarily by sliding your weight further back on the bike.  These suggestions typically won’t polarize the bike’s performance as much as dial it in across a wider range of terrain.  All the benefits of your headtube slackening are quickly lost in the marbles between corners if you can’t maintain your desired entrance line to the next corner.

Or let’s say you did modify your headtube angle.  Did you do it with an angled headset, fork travel adjustment, new fork with a different axle to crown, air spring sag and compression circuit adjustment, race spacers, rear suspension tune, tire size bias, etc?  How much did you need to go?  Which was the easiest, least expensive or most effective?  All are viable possibilities if you can define the problem.  Which mods are positive for your riding and which ones have the risk of side effects?

So what’s the answer?  Answer is there are no easy answers in this world.  Your bike’s performance is tied to how each component works with the next.  The more you progress as a rider the easier it is to see the performance differences.  Your neighbor who eyes your rig?  He’s impressed with your carbon fiber handlebars.  After a few seasons of riding you know that rise, sweep, angle, weight and strength all play factors into how the bar rides and how long it lasts.  With so many bikes offering a variety of immediate setups that affect geometry – think of the new models of 29” bikes which offer 120 or 140mm fork options, or the 26” bikes running 160, 150 or 140mm – you should Demand More of your resource and review what options will take your riding to the next level.  Your riding experience, aspirations, style, favorite trails type should be taken into account spec’ing your bike.  Are you being asked qualifying questions or shown a color matched component?  Does your resource’s staff understand the applied theory or just a % off MSRP?

The more complex your bike the more important it is to have a quality resource to work with on your spec.  If you are looking to ride the latest, most tech, dream rig it is even more critical you have an open relationship with an informed resource.  Build equity with your resource – be involved in your purchase – ask questions – be wary of manufacturers or retailers offering the magic “silver bullet” products.  Like our earlier equation illustrated the wrong component can do more harm than good.  It’s human nature to not want to buy parts twice – which usually means after you purchase something that doesn’t work right you start purchasing other components chasing your tail.

I hope this helps explain the intricacy that riders face when spec’ing builds.  See you on the trails – Nate@BikeCo.com

 

 

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