diff --git a/tig-benchmarker/common/structs.py b/tig-benchmarker/common/structs.py
index 05c48a68..025001c0 100644
--- a/tig-benchmarker/common/structs.py
+++ b/tig-benchmarker/common/structs.py
@@ -43,7 +43,7 @@ class BenchmarkSettings(FromDict):
     block_id: str
     challenge_id: str
     algorithm_id: str
-    size: int
+    race_id: str
 
     def calc_seed(self, rand_hash: str, nonce: int) -> bytes:
         return u8s_from_str(f"{jsonify(self)}_{rand_hash}_{nonce}")
@@ -274,9 +274,9 @@ class TopUp(FromDict):
 
 @dataclass
 class DifficultyData(FromDict):
-    num_solutions: int
+    average_solution_quality: int
     num_nonces: int
-    difficulty: Point
+    algorithm_id: str
 
 @dataclass
 class DepositDetails(FromDict):
diff --git a/tig-benchmarker/master/main.py b/tig-benchmarker/master/main.py
index 7648bbc4..f64177ca 100644
--- a/tig-benchmarker/master/main.py
+++ b/tig-benchmarker/master/main.py
@@ -2,7 +2,7 @@ import logging
 import os
 import time
 from master.data_fetcher import *
-from master.size_sampler import *
+from master.race_sampler import *
 from master.job_manager import *
 from master.precommit_manager import *
 from master.slave_manager import *
@@ -19,7 +19,7 @@ def main():
     client_manager.start()
 
     data_fetcher = DataFetcher()
-    size_sampler = SizeSampler()
+    race_sampler = RaceSampler()
     job_manager = JobManager()
     precommit_manager = PrecommitManager()
     submissions_manager = SubmissionsManager()
@@ -33,12 +33,12 @@ def main():
             if data["block"].id != last_block_id:
                 last_block_id = data["block"].id
                 client_manager.on_new_block(**data)
-                size_sampler.on_new_block(**data)
+                race_sampler.on_new_block(**data)
                 job_manager.on_new_block(**data)
                 submissions_manager.on_new_block(**data)
                 precommit_manager.on_new_block(**data)
             job_manager.run()
-            samples = size_sampler.run()
+            samples = race_sampler.run()
             submit_precommit_req = precommit_manager.run(samples)
             submissions_manager.run(submit_precommit_req)
             slave_manager.run()
diff --git a/tig-benchmarker/master/master/client_manager.py b/tig-benchmarker/master/master/client_manager.py
index a62d841a..b984ffb6 100644
--- a/tig-benchmarker/master/master/client_manager.py
+++ b/tig-benchmarker/master/master/client_manager.py
@@ -177,7 +177,7 @@ class ClientManager:
                     B.benchmark_id,
                     B.challenge,
                     B.algorithm,
-                    (B.settings->>'size')::INTEGER AS size,
+                    B.settings->>'race_id' as race_id,
                     B.batch_size,
                     B.num_nonces,
                     COALESCE(C.average_solution_quality, A.average_solution_quality) AS average_solution_quality,
diff --git a/tig-benchmarker/master/master/data_fetcher.py b/tig-benchmarker/master/master/data_fetcher.py
index 31e36e4f..6a453fc8 100644
--- a/tig-benchmarker/master/master/data_fetcher.py
+++ b/tig-benchmarker/master/master/data_fetcher.py
@@ -71,7 +71,10 @@ class DataFetcher:
             difficulty_responses = list(executor.map(_get, difficulty_urls))
         
         difficulty_data = {
-            c_id: [DifficultyData.from_dict(d) for d in resp.get("data", [])]
+            c_id: {
+                race_id: [DifficultyData.from_dict(x) for x in v]
+                for race_id, v in resp["data"].items()
+            }
             for c_id, resp in zip(challenges, difficulty_responses)
         }
 
diff --git a/tig-benchmarker/master/master/precommit_manager.py b/tig-benchmarker/master/master/precommit_manager.py
index 0642a904..10285463 100644
--- a/tig-benchmarker/master/master/precommit_manager.py
+++ b/tig-benchmarker/master/master/precommit_manager.py
@@ -18,54 +18,11 @@ class PrecommitManager:
         self.algorithm_name_2_id = {}
         self.challenge_name_2_id = {}
 
-    def on_new_block(
-        self,
-        block: Block,
-        precommits: Dict[str, Precommit],
-        benchmarks: Dict[str, Benchmark],
-        challenges: Dict[str, Challenge],
-        difficulty_data: Dict[str, List[DifficultyData]],
-        **kwargs
-    ):
+    def on_new_block(self, block: Block, **kwargs):
         self.last_block_id = block.id
         self.num_precommits_submitted = 0
-        benchmark_stats_by_challenge = {
-            c.details.name: {
-                "solutions": 0,
-                "nonces": 0,
-                "qualifiers": 0
-            }
-            for c in challenges.values()
-            if c.block_data is not None
-        }
-        for benchmark in benchmarks.values():
-            precommit = precommits[benchmark.id]
-            c_name = challenges[precommit.settings.challenge_id].details.name
-            benchmark_stats_by_challenge[c_name]["solutions"] += benchmark.details.num_solutions
-            benchmark_stats_by_challenge[c_name]["nonces"] += precommit.details.num_nonces
 
-        for c_name, x in benchmark_stats_by_challenge.items():
-            avg_nonces_per_solution = (x["nonces"] // x["solutions"]) if x["solutions"] > 0 else 0
-            logger.info(f"benchmark stats for {c_name}: (#nonces: {x['nonces']}, #solutions: {x['solutions']}, #qualifiers: {x['qualifiers']}, avg_nonces_per_solution: {avg_nonces_per_solution})")
-
-        aggregate_difficulty_data = {
-            c_id: {
-                "nonces": sum(
-                    x.num_nonces if x.difficulty in challenges[c_id].block_data.qualifier_difficulties else 0
-                    for x in difficulty_data
-                ),
-                "solutions": sum(
-                    x.num_solutions if x.difficulty in challenges[c_id].block_data.qualifier_difficulties else 0
-                    for x in difficulty_data
-                ),
-            }
-            for c_id, difficulty_data in difficulty_data.items()
-        }
-        for c_id, x in aggregate_difficulty_data.items():
-            avg_nonces_per_solution = (x["nonces"] // x["solutions"]) if x["solutions"] > 0 else 0
-            logger.info(f"global qualifier difficulty stats for {challenges[c_id].details.name}: (#nonces: {x['nonces']}, #solutions: {x['solutions']}, avg_nonces_per_solution: {avg_nonces_per_solution})")
-
-    def run(self, size_samples: Dict[str, List[int]]) -> SubmitPrecommitRequest:
+    def run(self, race_samples: Dict[str, List[int]]) -> SubmitPrecommitRequest:
         num_pending_jobs = get_db_conn().fetch_one(
             """
             SELECT COUNT(*) 
@@ -92,11 +49,11 @@ class PrecommitManager:
                 algorithm_id=a_id,
                 player_id=CONFIG["player_id"],
                 block_id=self.last_block_id,
-                size=size_samples[a_id]
+                race_id=race_samples[a_id]
             ),
             num_nonces=selection["num_nonces"],
             hyperparameters=selection["hyperparameters"],
             runtime_config=selection["runtime_config"],
         )
-        logger.info(f"Created precommit (algorithm_id: {a_id}, size: {req.settings.size}, num_nonces: {req.num_nonces}, hyperparameters: {req.hyperparameters}, runtime_config: {req.runtime_config})")
+        logger.info(f"Created precommit (algorithm_id: {a_id}, race: {req.settings.race_id}, num_nonces: {req.num_nonces}, hyperparameters: {req.hyperparameters}, runtime_config: {req.runtime_config})")
         return req
\ No newline at end of file
diff --git a/tig-benchmarker/master/master/size_sampler.py b/tig-benchmarker/master/master/race_sampler.py
similarity index 53%
rename from tig-benchmarker/master/master/size_sampler.py
rename to tig-benchmarker/master/master/race_sampler.py
index 2b8223ec..da3320f9 100644
--- a/tig-benchmarker/master/master/size_sampler.py
+++ b/tig-benchmarker/master/master/race_sampler.py
@@ -9,13 +9,13 @@ logger = logging.getLogger(os.path.splitext(os.path.basename(__file__))[0])
 
 Point = List[int]
 
-class SizeSampler:
+class RaceSampler:
     def __init__(self):
         self.valid_size_ranges = {}
 
     def on_new_block(self, block: Block, **kwargs):
-        self.allowed_sizes = {
-            c_id: d["difficulty"]["allowed_sizes"]
+        self.active_race_ids = {
+            c_id: d["active_race_ids"]
             for c_id, d in block.config["challenges"].items()
         }
 
@@ -25,14 +25,14 @@ class SizeSampler:
         for config in CONFIG["algo_selection"]:
             a_id = config["algorithm_id"]
             c_id = a_id[:4]
-            allowed_sizes = self.allowed_sizes[c_id]
+            active_races = self.active_race_ids[c_id]
 
-            selected_sizes = sorted(set(config["selected_sizes"]) & set(allowed_sizes))
-            if len(selected_sizes) == 0:
-                selected_sizes = list(allowed_sizes)
-            config["selected_sizes"] = selected_sizes
+            selected_races = sorted(set(config["selected_races"]) & set(active_races))
+            if len(selected_races) == 0:
+                selected_races = list(active_races)
+            config["selected_races"] = selected_races
 
-            samples[a_id] = random.choice(selected_sizes)
-            logger.debug(f"Selected size {samples[a_id]} for algorithm {a_id} in challenge {c_id}")
+            samples[a_id] = random.choice(selected_races)
+            logger.debug(f"Selected race '{samples[a_id]}' for algorithm {a_id} in challenge {c_id}")
                 
         return samples
\ No newline at end of file
diff --git a/tig-benchmarker/postgres/init.sql b/tig-benchmarker/postgres/init.sql
index 0ce45ec9..23a121b4 100644
--- a/tig-benchmarker/postgres/init.sql
+++ b/tig-benchmarker/postgres/init.sql
@@ -116,7 +116,7 @@ SELECT '
     {
       "algorithm_id": "c001_a001",
       "num_nonces": 40,
-      "selected_sizes": [],
+      "selected_races": [],
       "weight": 1,
       "batch_size": 8,
       "hyperparameters": null,
@@ -128,7 +128,7 @@ SELECT '
     {
       "algorithm_id": "c002_a001",
       "num_nonces": 40,
-      "selected_sizes": [],
+      "selected_races": [],
       "weight": 1,
       "batch_size": 8,
       "hyperparameters": null,
@@ -140,7 +140,7 @@ SELECT '
     {
       "algorithm_id": "c003_a001",
       "num_nonces": 40,
-      "selected_sizes": [],
+      "selected_races": [],
       "weight": 1,
       "batch_size": 8,
       "hyperparameters": null,
@@ -152,7 +152,7 @@ SELECT '
     {
       "algorithm_id": "c004_a001",
       "num_nonces": 40,
-      "selected_sizes": [],
+      "selected_races": [],
       "weight": 1,
       "batch_size": 8,
       "hyperparameters": null,
@@ -164,7 +164,7 @@ SELECT '
     {
       "algorithm_id": "c005_a001",
       "num_nonces": 40,
-      "selected_sizes": [],
+      "selected_races": [],
       "weight": 1,
       "batch_size": 8,
       "hyperparameters": null,
@@ -176,7 +176,7 @@ SELECT '
     {
       "algorithm_id": "c006_a001",
       "num_nonces": 40,
-      "selected_sizes": [],
+      "selected_races": [],
       "weight": 1,
       "batch_size": 8,
       "hyperparameters": null,
diff --git a/tig-benchmarker/tests/data.py b/tig-benchmarker/tests/data.py
index e12e3870..e8a1a6dc 100644
--- a/tig-benchmarker/tests/data.py
+++ b/tig-benchmarker/tests/data.py
@@ -27,7 +27,7 @@ class TestData(unittest.TestCase):
             block_id="some_block",
             challenge_id="some_challenge",
             algorithm_id="some_algorithm",
-            difficulty=[1, 2, 3]
+            race_id="a=1,b=2"
         )
 
         rand_hash = "random_hash"
@@ -35,8 +35,8 @@ class TestData(unittest.TestCase):
 
         # Assert same as Rust version: tig-structs/tests/core.rs
         expected = bytes([
-            135, 168, 152, 35, 57, 28, 184, 91, 10, 189, 139, 111, 171, 82, 156, 14, 
-            165, 68, 80, 41, 169, 236, 42, 41, 198, 73, 124, 78, 130, 216, 168, 67
+            122, 94, 247, 46, 146, 71, 140, 234, 78, 160, 235, 180, 79, 32, 69, 205, 247, 91, 94,
+            43, 231, 184, 120, 114, 182, 226, 24, 176, 227, 170, 72, 31
         ])
         self.assertEqual(settings.calc_seed(rand_hash, nonce), expected)
 
diff --git a/tig-benchmarker/ui/src/app/pages/home/home.component.html b/tig-benchmarker/ui/src/app/pages/home/home.component.html
index 6dab9ebc..97b43a5e 100644
--- a/tig-benchmarker/ui/src/app/pages/home/home.component.html
+++ b/tig-benchmarker/ui/src/app/pages/home/home.component.html
@@ -88,8 +88,8 @@
         <th pSortableColumn="algorithm" class="tig-dark text-center">
           ALGORITHM
         </th>
-        <th pSortableColumn="size" class="tig-dark text-center">
-          INST. SIZE
+        <th pSortableColumn="race_id" class="tig-dark text-center">
+          RACE
         </th>
         <th pSortableColumn="batch_size" class="tig-dark text-center">
           BATCH SIZE
@@ -142,7 +142,7 @@
         </td>
         <td class="row-cell">
           <div class="flex justify-content-center align-items-center">
-            [{{ benchmark.size }}]
+            [innerHTML]="formatRaceId(benchmark.race_id)">
           </div>
         </td>
         <td class="row-cell">
diff --git a/tig-benchmarker/ui/src/app/pages/home/home.component.ts b/tig-benchmarker/ui/src/app/pages/home/home.component.ts
index dd5bb01c..35e2ad20 100644
--- a/tig-benchmarker/ui/src/app/pages/home/home.component.ts
+++ b/tig-benchmarker/ui/src/app/pages/home/home.component.ts
@@ -123,4 +123,11 @@ export class HomeComponent {
       clearInterval(this.interval);
     }
   }
+  
+  formatRaceId(value: string): string {
+    if (!value) return '';
+    return value
+      .replace(/=/g, ': ')
+      .replace(/,/g, '<br>');
+  }
 }