Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
App Overview
Bike Calculator Pro
Bike Calculator Pro is the pro version of the original Bike Calculator iOS app released in 2010
$2.99 · In-app purchases
PRICE
$2.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.0
1 ratings · Top 30%
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
Build your own version
Build Kit
Make this idea yours
A product spec, screen plans, and build steps for your coding agent.
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Add to a Remix
Combine features and design from your favorite apps.
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What should your app do differently? Your note travels with the kit so your coding agent builds around your idea.
What's included15 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Screen plan
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Differentiate and validate
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Bike Calculator Pro: map the core Health & Fitness workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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Opportunities
AI-GENERATED OPPORTUNITY HYPOTHESES
These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Add more performance metrics like elevation gain, power output.
Assumption to check: Limited features compared to other fitness apps
Validate with people who use this workflow before building.
Hypothesis 2
Implement a more visually appealing UI with animations.
Assumption to check: User interface could be more engaging
Validate with people who use this workflow before building.
Hypothesis 3
Incorporate social sharing options for rides and achievements.
Assumption to check: No social features or community aspect
Validate with people who use this workflow before building.
Hypothesis 4
Offer a freemium model with essential features free and premium features additional.
Assumption to check: Pricing model may deter users
Validate with people who use this workflow before building.
App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
App Store description
Bike Calculator Pro is the pro version of the original Bike Calculator iOS app released in 2010. It is a performance calculator. You and your bike are a machine subject to external forces that you - the engine - must overcome in order to move. Bike Calculator estimates how fast you'll go, how much time you will take, how much energy you will use and more. This app and our original Bike Calculator app are not gear calculators. The pro version was developed in association with www.bikecalculator.com and incorporates many enhancements including a new segments view and new energy output options for eBikes and kilojoules.
Written user reviews are not shown here. Check current App Store reviews >
Screenshots
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Build scope
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Define the first version
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Set boundaries
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Check the hard parts
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
SUGGESTED BUILD STACK
React Native
Expo
Axios
react-native-reanimated
@react-native-community/hooks
React Navigation
BUILD KIT DIFFICULTY
Intermediate
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.
