Predictika · Bicycle components

An AI sales agent's road bike drivetrain build, checked before it goes out

An AI sales agent prepares a build sheet for a Shimano 2x12-speed road or gravel rear drivetrain for a bike shop: the shifter, rear derailleur, cassette, chain and wheel, and the largest sprocket on the cassette. Before it goes out, the agent sends the build to Predictika, which checks it against a declarative model of Shimano's published 2x12-speed rear drivetrain compatibility chart and returns a verdict, every reason and the derailleur range it computed. The shop is fictional.

Scope: Shimano ROAD/Gravel 2x12-speed rear drivetrains (Dura-Ace R9250, Ultegra R8150, 105 R7150 and R7100, GRX RX825, RX820 and RX610): shifter, rear derailleur, cassette, chain and wheel. See everything this validator covers

This validator models builds of Shimano 2x12-speed road and gravel rear drivetrains, based on chart C-454 of Shimano's Products compatibility information (Ver 2.7, October 7, 2026), not just the scenarios shown below.

  • Two groups — the 105 R7100, GRX RX820 and RX610 group (ST-R7120, ST-RX820, ST-RX610 with RD-R7100 or RD-RX820) and the Dura-Ace R9250, Ultegra R8150, 105 R7150 and GRX RX825 group (eleven shifters with RD-R9250, RD-R8150, RD-R7150 or RD-RX825); a shifter and derailleur from different groups are blocked.
  • Cassettes — CS-R8101-12, CS-R7101-12 and CS-HG710-12 for the first group; those plus CS-R9200-12, CS-R8100-12 and CS-R7100-12 for the second.
  • Chain and wheel — CN-M9100, CN-M8100, CN-M7100 or CN-M6100; twenty wheels and freehubs from the chart. A wheel the chart does not list needs a person to confirm its freehub fit.
  • Derailleur capacity — the largest-sprocket range the chart gives each derailleur (30 to 34 teeth for RD-R9250 and RD-R8150, 34 to 36 teeth for the others), and the capacity the build sheet states.
  • Discontinued parts — parts the chart shows as discontinued (CS-R8100-12, CS-R7100-12, WH-RS770, WH-RX830, WH-U5000) need a person to confirm availability.

Any 2x12-speed road or gravel build of these parts is in scope — not only the scenarios pictured here. Not covered: 2x11, 1x12 and earlier speed counts, mountain bike and e-bike drivetrains, brakes, crankset and front derailleur, prices (this chart gives none), and which cassette has which largest sprocket (the build declares it).

The AI sales agentBuilds the drivetrain build sheet from the customer's order and says it is ready.
Predictika validatorChecks every rule at once and returns the verdict, each finding, and the computed figures.

7 scenarios in 3 groups · each group runs from the agent’s first attempt to the outcome · click one to switch

What the agent proposes

The AI sales agent says

Illustrative agent statement. The validator receives the structured request below.

Proposing agent: AI sales agent (scripted)

Before sending, the agent must call Recorded run

Predictika validator


      

        
        
        
      

      
Waiting for the call.

      
    

  

  
  

    
Where rules-based CPQ gets it wrong
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Our assessment of what a typical rules-based CPQ (product rules, price rules and validation rules, as in Salesforce CPQ) does with the same cases. It is a judgment about effort and reliability, not a claim that nothing can be built.

    
What the validator caughtTypical rules-based CPQPredictika
A shifter and derailleur from different groupsOnly with workarounds
The chart pairs shifters with derailleurs in two groups. A rules-based CPQ needs a pairing rule for every shifter and derailleur combination, and each new model means new rules.		The shifter and derailleur arrive in one request and the group pairing is checked on every call.
A largest sprocket the derailleur cannot takeOnly with care
The range depends on the derailleur, and the cassette's largest sprocket is a separate figure. A rule can compare them, but each derailleur needs its own limits kept in step with the chart.		The range is computed from the derailleur and compared with the build on every call, at both ends.
Parts of a different speed countOnly with care
An 11-speed chain or cassette is easy to leave in a 12-speed build when the part list is long; a rule has to name every wrong part.		Anything the 2x12-speed chart does not list is flagged, wherever it sits in the build.
Every problem returned in one answerOnly with workarounds
Rules tend to fire as the order is saved or a step is completed, so a person often fixes one error and meets the next.		All findings come back together, whatever order the choices arrived in.

  

  

    
What this validator catches: findings from its test cases
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Every rule is checked on every call, in any order the choices arrive; one problem never hides another. Blocking findings stop the quote; approval findings need a person to sign off; everything else is computed.

    
1The chart shows a part in this build as discontinued; a person should confirm it is still available before the build is sent.
2The chart lists only the CS-R8101-12, CS-R7101-12 and CS-HG710-12 for the RD-R7100 and RD-RX820; the cassette ordered is a different one.
3The wheel is not one the 2x12-speed chart lists; a person should confirm its freehub fit against Shimano chart C-731.
4The shifter ordered is not on the 2x12-speed rear drivetrain chart; Shimano lists it on the 2x11-speed chart.
5The rear derailleur ordered is not on the 2x12-speed rear drivetrain chart; Shimano lists it on the 2x11-speed chart.
6The cassette ordered is not on the 2x12-speed rear drivetrain chart; Shimano lists it on the 2x11-speed chart.
7The chain ordered is not one of the chains the 2x12-speed chart lists (CN-M9100, CN-M8100, CN-M7100, CN-M6100); it is an 11-speed chain.
8The shifter ordered is from the 105 R7100 / GRX RX820 / RX610 group, which the chart pairs only with the RD-R7100 and RD-RX820; the derailleur ordered is a different one.
9The shifter ordered is from the Dura-Ace R9250, Ultegra R8150, 105 R7150 and GRX RX825 group, which the chart pairs with the RD-R9250, RD-R8150, RD-R7150 and RD-RX825; the derailleur ordered is a different one.
10The build has a largest sprocket of 28 teeth; the chart requires at least 30 teeth for this derailleur.
11The build has a largest sprocket of 36 teeth; the chart allows up to 34 teeth for this derailleur.
12The build has a largest sprocket of 32 teeth; the chart requires at least 34 teeth for this derailleur.
13The build has a largest sprocket of 38 teeth; the chart allows up to 36 teeth for this derailleur.
14The build sheet states that the derailleur takes a largest sprocket of up to 32 teeth; the chart gives 34 teeth for this derailleur.
15The build sheet states that the derailleur takes a largest sprocket of up to 34 teeth; the chart gives 36 teeth for this derailleur.
16The build has a largest sprocket of 40 teeth; the chart allows up to 34 teeth for this derailleur.
17The build sheet states that the derailleur takes a largest sprocket of up to 36 teeth; the chart gives 34 teeth for this derailleur.

  

  

    
Scenarios and results
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The recorded result of the validator for each scenario on this page: the request the AI agent sent, the verdict, and every finding, in the order they appear above.

    
1. Shifter and derailleur groups: Dura-Ace derailleur on a 105 R7100 shifter

    
The agent's request. Please prepare the build sheet for a Shimano 2x12-speed road bike: shifter ST-R7120, rear derailleur RD-R9250, cassette CS-R8101-12 with a largest sprocket of 34 teeth, chain CN-M8100 and wheel WH-R8170. The build sheet states that the RD-R9250 takes a largest sprocket of up to 34 teeth. It is ready to send.

    
Verdict: Blocked.

    
    
      
  • Shifter from the 105 R7100 / GRX RX820 / RX610 group with a derailleur from the other group. The shifter ordered is from the 105 R7100 / GRX RX820 / RX610 group, which the chart pairs only with the RD-R7100 and RD-RX820; the derailleur ordered is a different one.
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2. Shifter and derailleur groups: The agent resubmits after fixing the errors

    
The agent's request. Please prepare the build sheet for a Shimano 2x12-speed road bike: shifter ST-R7120, rear derailleur RD-R7100, cassette CS-R8101-12 with a largest sprocket of 34 teeth, chain CN-M8100 and wheel WH-R8170. The build sheet states that the RD-R7100 takes a largest sprocket of up to 36 teeth. It is ready to send.

    
Verdict: Allowed.

    
    
      
  • Chart range. The chart gives this derailleur a largest sprocket of 34 to 36 teeth.
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3. Largest sprocket: A 36-tooth cassette on an Ultegra derailleur

    
The agent's request. Please prepare the build sheet for a Shimano 2x12-speed road bike: shifter ST-R8170, rear derailleur RD-R8150, cassette CS-R8100-12 with a largest sprocket of 36 teeth, chain CN-M8100 and wheel WH-R8170. It is ready to send.

    
Verdict: Blocked.

    
    
      
  • Largest sprocket above the derailleur range. The build has a largest sprocket of 36 teeth; the chart allows up to 34 teeth for this derailleur.
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  • Part shown as discontinued in the chart. The chart shows a part in this build as discontinued; a person should confirm it is still available before the build is sent.
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4. Largest sprocket: The agent resubmits after fixing the errors

    
The agent's request. Please prepare the build sheet for a Shimano 2x12-speed road bike: shifter ST-R8170, rear derailleur RD-R8150, cassette CS-R8100-12 with a largest sprocket of 34 teeth, chain CN-M8100 and wheel WH-R8170. The build sheet states that the RD-R8150 takes a largest sprocket of up to 34 teeth. It is ready to send.

    
Verdict: Needs approval.

    
    
      
  • Part shown as discontinued in the chart. The chart shows a part in this build as discontinued; a person should confirm it is still available before the build is sent.
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  • Chart range. The chart gives this derailleur a largest sprocket of 30 to 34 teeth.
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5. Largest sprocket: The agent resubmits after fixing the errors

    
The agent's request. Please prepare the build sheet for a Shimano 2x12-speed road bike: shifter ST-R8170, rear derailleur RD-R8150, cassette CS-R9200-12 with a largest sprocket of 34 teeth, chain CN-M8100 and wheel WH-R8170. The build sheet states that the RD-R8150 takes a largest sprocket of up to 34 teeth. It is ready to send.

    
Verdict: Allowed.

    
    
      
  • Chart range. The chart gives this derailleur a largest sprocket of 30 to 34 teeth.
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6. Speed count: An 11-speed chain and cassette in a gravel build

    
The agent's request. Please prepare the build sheet for a Shimano 2x12-speed road bike: shifter ST-RX825, rear derailleur RD-RX825, cassette CS-R8000 with a largest sprocket of 36 teeth, chain CN-HG701-11 and wheel WH-RX870. The build sheet states that the RD-RX825 takes a largest sprocket of up to 36 teeth. It is ready to send.

    
Verdict: Blocked.

    
    
      
  • Cassette not on the 2x12 chart. The cassette ordered is not on the 2x12-speed rear drivetrain chart; Shimano lists it on the 2x11-speed chart.
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  • Chain not on the 2x12 chart. The chain ordered is not one of the chains the 2x12-speed chart lists (CN-M9100, CN-M8100, CN-M7100, CN-M6100); it is an 11-speed chain.
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7. Speed count: The agent resubmits after fixing the errors

    
The agent's request. Please prepare the build sheet for a Shimano 2x12-speed road bike: shifter ST-RX825, rear derailleur RD-RX825, cassette CS-R8101-12 with a largest sprocket of 36 teeth, chain CN-M6100 and wheel WH-RX870. The build sheet states that the RD-RX825 takes a largest sprocket of up to 36 teeth. It is ready to send.

    
Verdict: Allowed.

    
    
      
  • Chart range. The chart gives this derailleur a largest sprocket of 34 to 36 teeth.
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Narration transcript
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The text of the narrated walkthrough, step by step.

    
    
      
  1. Welcome to a demo of Predictika's Validator. An AI sales agent prepares a build sheet for a Shimano 2x12-speed road or gravel rear drivetrain for a bike shop: the shifter, rear derailleur, cassette, and more. Before it goes out, the agent sends the build to Predictika, which checks it against a declarative model of Shimano's published 2x12-speed rear drivetrain compatibility chart and returns a verdict, every reason and the derailleur range it computed. The shop is fictional.
    2. 
      
  2. I will start with the first request by the agent.
    3. 
      
  3. The agent says. Please prepare the build sheet for a Shimano 2x12-speed road bike: shifter ST-RX825, rear derailleur RD-RX825, cassette CS-R8000 with a largest sprocket of 36 teeth, chain CN-HG701-11 and wheel WH-RX870. The build sheet states that the RD-RX825 takes a largest sprocket of up to 36 teeth. The rest of the request is on screen.
    4. 
      
  4. Before it goes out, the agent calls the validator.
    5. 
      
  5. Blocked, with two findings, all in one answer. The cassette ordered is not on the 2x12-speed rear drivetrain chart; Shimano lists it on the 2x11-speed chart. The chain ordered is not one of the chains the 2x12-speed chart lists, such as the CN-M9100 and CN-M8100; it is an 11-speed chain.
    6. 
      
  6. The validator returned two blocking findings in one answer. A check that reads one field at a time would pass most of this; it shows only when the choices in the quote are checked against each other.
    7. 
      
  7. What this shows: for parts of a different speed count, a rules-based CPQ is error-prone for this.
    8. 
      
  8. Now the agent resubmits.
    9. 
      
  9. The corrected request. It changes the cassette to CS-R8101-12 and the chain to CN-M6100.
    10. 
      
  10. It calls the validator again.
    11. 
      
  11. This time the validator clears it.
    12. 
      
  12. Both earlier findings are cleared, and the validator's figure matches the quote.
    13. 
      
  13. Two problems caught in one call, fixed in one pass, and a clean quote. That is the value of Predictika's validator: catching mistakes before they reach the customer. Now you can try the other scenarios yourself.
    14.