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Design feature is only available on displays at 1024px or greater

BAR REACH 610 mm GROUND CLEARANCE 95 mm SEAT TUBE ANGLE 73 deg BAR STACK 450 mm SADDLE HEIGHT 625 mm FRONT TYRE CLEARANCE 10 mm REAR TYRE CLEARANCE 10 mm 5 mm CLEARANCE TOE FRAME REACH 510 mm FRAME STACK mm HEAD TUBE ANGLE deg BOTTOM BRACKET DROP mm FORK RAKE mm CHAINSTAY LENGTH mm STEM ANGLE deg TOP TUBE ANGLE STEM LENGTH mm CRANK LENGTH mm RESPONSE FACTOR STEERING FACTOR Grey = All data. White = Your size. AGILE QUICK STABLE SLOW VERTICAL COMPLIANCE TORSIONAL STIFFNESS ISOLATED RESPONSIVE DIRECT FORGIVING

Stem & Bar Combination Used for Analysis

SizeXXSXSSMLXLXXL
Stem809090100110110120
Handlebar380400420420420440440

Engineer Your Bike

Frame Mass
200g

Total Mass
2.5kg

Base Options

Fork & Axle Type
Reference Size This will determine your starting geometry and highlight models in this size in the steering & response graph.

Geometry

Frame Stack ( mm)
Frame Reach ( mm)
Head Tube Angle ( deg)
Fork Rake ( mm)
Seat Tube Angle ( deg)
Bottom Bracket Drop ( mm)
Chain Stay ( mm) A longer chainstay will provide better shift quality.
Top Tube Angle ()Sloping geometry is more compliant.
Saddle Height ( mm)
Stem Length ()
Stem Angle( deg)
Stem Spacer ( mm)
Crank Length ()
Handlebar Width ()
Handlebar Reach ()

Stiffness

Flex Level

Components

Bar & Stem
Saddle
Rims
Hubs & Spokes
Tyres & Tubes
Groupset
Chainring
Cassette
Bottom Bracket
Pedals
Brake Routing
Special Order

Colour

Hubs
Lugs & Headbadge
Paint
Logo
Bar Tape
Saddle

Custom Text

Drive Side Dropout
Non-Drive Side Dropout

Research

YOUR BIKE. YOUR WAY. OUR CRAFT.

We believe you are the best person to design your bespoke custom bike. Our mission is to empower you to direct the design of your bike – tuning it to your specific needs. All you need is the right information.

To guide you, in “Engineer Your Bike” you are able to compare each of these factors to the top products in the market, giving you a real world reference point.

With the following four simple factors you can adequately tune the performance of your bike:
1. Steering – How sensitive the steering is to rider inputs
2. Response – How sensitive the bike is to steering inputs
3. Torsional Stiffness – How stiff the bike is in cornering
4. Vertical Compliance – How compliant the bike is at the saddle

STEERING FACTOR

Combining the concepts of “Flop Factor” and “Steering Gain”,
a higher steering factor equates to a faster steering bike.

“Flop Factor” is the amount the front wheel “flops” as the handlebars are rotated. A higher Flop Factor is experienced as quicker or more sensitive steering, similar to power steering in a car. A lower head tube angle will amplify it, making the steering quicker.

“Steering Gain” is the amount of leverage in the steering system and is proportional to your stem and bar size. A longer stem, or wider bars will make the steering slower.

You may think the Head Tube Angle relationship should be the opposite. Race bikes have high head tube angles. Aren’t they fast steering? Not necessarily, as steering and response can be confused.

RESPONSE FACTOR

Once it has been steered the bike will respond by moving laterally in an arc. The “Response Factor” is our method of capturing this response, with a higher value being more agile or manoeuvrable. But overdo it and it will become too sensitive and require constant correction.

To calculate it we use established methods from motorcycle dynamics involving the front and rear normal trails and weight distribution.

It is sensitive to the front trail meaning the Head Tube Angle is the most important factor. A higher Head Tube Angle makes the bike more agile as is found in race bikes. Fine tuning is also possible by modifying the Chainstay Length, or Frame Reach.

TORSIONAL STIFFNESS

Sometimes referred to as Steering Rigidity or Head Tube Stiffness, it is actually the torsional stiffness of the entire frame from fork to rear dropout. To measure this, the frame is twisted at the head tube using a dummy fork and with the rear dropout mounted on an axle.

A higher stiffness frame will deflect less under load creating a more direct response. This develops a faster response when cornering, but will be less forgiving over bumps.

You can compare our lay-up options to the existing products in the market to help you decide the stiffness you prefer. If you are still unsure please contact us and we will give you our advice based on your frame size, rider weight and riding style.

VERTICAL COMPLIANCE

There is a strong correlation between vertical compliance and comfort. For most riders more compliance is better, but some energy is lost when pedalling while seated due to seat post flex. Some riders don’t like the feeling of a flexible seat post and prefer a more direct connection with the road.

Whilst vertical compliance is a dominating factor in ride comfort, damping also plays a significant role. This is where Bastion’s breakthrough frame technology has an advantage. Using Titanium lugs formed into intricate shapes we are able to achieve the torsional stiffness of the best carbon frames, but with a smoother ride.

Be aware that Top Tube Angle plays a significant role in Vertical Compliance. Please make sure to select this carefully.

ENGINEER YOUR BIKE

Perfection is subjective and your voice is the one that counts. Within the dimensions of your bike fit, you can tune the performance of the bike to suit you and the way you ride.

Head Tube Angle should be your primary tuning tool, but also, Frame Reach, Bottom Bracket Drop, and Chainstay and Stem Length can be used for fine tuning.

If you have any questions please do not hesitate to contact us. We would be pleased to advise you if you are unsure.