https://forums.garmin.com/developer/fit-sdk/A place to ask and answer questions related to the Flexible and Interoperable Data Transfer (FIT) Protocol.en-USTelligent Community 13https://forums.garmin.com/developer/fit-sdk/f/discussion/439649/recommended-integration-architecture-for-a-web-based-cycling-coaching-platformFri, 10 Jul 2026 13:45:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:a28b80ad-8890-41a9-92cc-0408c353ffe67349784Hello Garmin Developers, I am developing a web-based cycling coaching platform that analyzes completed cycling activities to generate personalized ride recommendations. Unlike applications that only use activity summaries, our recommendation engine depends on the original FIT activity files because we derive additional physiological and performance metrics from second-by-second telemetry such as power, cadence, heart rate, GPS, elevation and speed. Before implementing the platform, I would like to understand Garmin's recommended integration architecture. For a web-based coaching platform where users authorize access to their Garmin Connect accounts, is the Garmin Connect Activity API the recommended approach for automatically receiving completed FIT activity files? Or is there another supported integration that Garmin recommends for platforms performing post-ride analytics and coaching? The platform is currently under development and will initially be evaluated with a small community of cyclists before a broader public release. Any guidance would be greatly appreciated. Thank you.https://forums.garmin.com/developer/fit-sdk/f/discussion/435484/developer-onboarding-blocked/2044441Fri, 10 Jul 2026 13:41:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:e1c6b47f-b7c6-44b6-b09a-91e61ca756eb7349784Hi, I'm experiencing something similar. I submitted an inquiry regarding the Garmin Connect Developer Program for a web-based cycling coaching platform and haven't received a response yet. Has anyone recently been approved for the Activity API, or is onboarding currently delayed?https://forums.garmin.com/developer/fit-sdk/f/discussion/439240/swim-interval-summary-screen-during-programmed-workouts/2043535Tue, 07 Jul 2026 09:52:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:8f1aee00-334f-4a40-8a8d-dbb193a600496146796From what’s been shared by Garmin developers, the SDK doesn’t currently provide a way to trigger the same interval summary screen during rest periods that appears in free swim mode. The summary view with countdown is built into Garmin’s native workout logic, but isn’t exposed through custom SDK programming—so while you can design custom swim workouts, replicating that exact screen isn’t supported at this time. www rootinsurance comhttps://forums.garmin.com/developer/fit-sdk/f/discussion/439242/requesting-manufacturer-id/2043324Mon, 06 Jul 2026 17:43:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:de4cdf76-5dae-45c7-bc59-24a68db49db5Ben FITSend an email to eng.busdev at garmin.com with your request, and give them a few days to reply.https://forums.garmin.com/developer/fit-sdk/f/discussion/439242/requesting-manufacturer-idFri, 03 Jul 2026 23:24:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:f20700d6-7054-4a61-b86a-bfe0dbf6fd854380222Hi, I work for a company that manufactures a device that produces FIT files. I'd like to request a Manufacturer ID to use instead of the developer value 255. I gather this used to be done via thisisant.com. There is a form linked from https://www.thisisant.com/developer/resources/tech-support/ but I can't access that even when logged in as the highest level of membership currently available (ANT+ Adopter). What is the process now that ANT+ Membership has closed?https://forums.garmin.com/developer/fit-sdk/f/discussion/439240/swim-interval-summary-screen-during-programmed-workoutsFri, 03 Jul 2026 22:03:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:e075c256-e003-4bf2-a7ee-1a66d6956ba8edwardsmsWhen programming a Swim workout via the SDK is there any way to get a Garmin Forerunner 970 to show the interval summary screen during the rest periods. The screen I want is the same screen the watch shows when doing a free workout. I swim some laps, press the lap button and a screen with a summary of the last set appears with a countdown timer for the rest period.https://forums.garmin.com/developer/fit-sdk/f/discussion/437310/python-sdk-weight_scale-weight---potential-bug/2040328Wed, 24 Jun 2026 15:18:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:f53f603b-218c-4e3d-8563-f932d7b716d38294519Thanks for the explanation and the fix! I uploaded some new data and it indeed has been corrected.https://forums.garmin.com/developer/fit-sdk/f/discussion/438278/attrezzatura/2040050Tue, 23 Jun 2026 19:43:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:e07f82d0-c78e-4eea-b75f-60c5e8cae928Ben FITThere is a similar question in the Connect Web App forum. I suggest posting your question there to show your support for this feature request. RE: Gear Trackinghttps://forums.garmin.com/developer/fit-sdk/f/discussion/438278/attrezzaturaThu, 18 Jun 2026 09:53:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:0a991d5d-ef91-466d-b890-b7cc00dd76b52025128come faccio ad azzerrare i km dell'attrezzatura? Ho appena impostato catena e copertoni, ma uun copertone ha 2.000 km come faccio a cambiare i km e non farlo partire da 0? graziehttps://forums.garmin.com/developer/fit-sdk/f/discussion/437310/python-sdk-weight_scale-weight---potential-bug/2038763Wed, 17 Jun 2026 14:00:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:48b8ae07-ddc8-4a68-85c3-2f59fd03532dEli FITWith the release of the 21.208 SDK, this behavior is now fixed. Weight in the weight_scale mesg is now properly a uint16 and will apply scale as expected when either encoding or decoding data. The new version was published to PyPi available here: https://pypi.org/project/garmin-fit-sdk/https://forums.garmin.com/developer/fit-sdk/f/discussion/437845/create-workout-with-steps-using-the-sdkWed, 10 Jun 2026 17:04:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:aff0d127-5cf5-4cfe-ab45-7b5e1bf51df6RePeterHi, I am currently developing a strength training application for my Garmin watch. The application is able to record an activity using the Toybox.ActivityRecording.Session. After running the workout with session.start(), session.stop() and session.save(), the activity is stored on my device and is uploaded to Garmin Connect. If I create a strength training with my watch using the standard strength training app, I have a number of sets including reps, the time of the set and the time of the pause. It looks like this in Garmin Connect: When I create an activity with my self made application, I cannot add any sets to the strength training. The method 'createFIeld(...) is not creating the correct data field in the FIT file. By decoding the FIT file from my watch, I found the required data that is used to create the sets inside the Garmin Connect app: [ {...}, { "frame_type": "definition_message", "name": "set", "header": { "local_mesg_num": 2, "time_offset": null, "is_developer_data": false }, "global_mesg_num": 225, "endian": "<", "field_defs": [ ... ], "dev_field_defs": [], "chunk": { "index": 13, "offset": 1546, "size": 51 } }, {...} ] Therefore, I tried to create the data inside my application, but haven't found any way to create the data field for sets. Does anybody know, how to add the sets to my application, so I can view the sets inside the Garmin Connect app?fieldsdkFIT datahttps://forums.garmin.com/developer/fit-sdk/f/discussion/389942/looking-for-corrupt-fit-files/2036743Sun, 07 Jun 2026 05:58:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:d8a504d6-b0ee-4366-ad24-a0e7c3b7b295AlanNo worries. Next time when you have such files, you can upload them here.https://forums.garmin.com/developer/fit-sdk/f/discussion/389942/looking-for-corrupt-fit-files/2036619Sat, 06 Jun 2026 12:12:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:dca9b199-17ee-4478-9cbd-016129e572e4Duma-70thanks Alan but it's been so long that I don't have the file anymore.https://forums.garmin.com/developer/fit-sdk/f/discussion/389942/looking-for-corrupt-fit-files/2036618Sat, 06 Jun 2026 11:51:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:2197af98-22a1-4b21-8b67-5e7c1417fd3fDuma-70thank you for trying. it didn't work.https://forums.garmin.com/developer/fit-sdk/f/discussion/389942/looking-for-corrupt-fit-files/2036564Sat, 06 Jun 2026 03:16:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:33d9ddda-a867-4183-9c36-627b97f593ccAlanCan you upload your corrupt files to Google Drive or attached to a reply so that I can analyze them for you? Currently my understanding of the FIT file is on the official FIT file format specification at https://developer.garmin.com/fit/protocol/ . So if a file is corrupt, I can try to make it follow the specification. It is interesting to see other possible corruption patterns which makes the data look strange though the file still follow the specification.https://forums.garmin.com/developer/fit-sdk/f/discussion/389942/looking-for-corrupt-fit-files/2036383Fri, 05 Jun 2026 10:42:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:565734a5-2d5c-4193-9f3c-9e8094b2c9f84870762I may be able to help with testing. I have encountered several corrupted FIT files over the years due to interrupted syncs, device freezes, and incomplete activity saves. Corrupt FIT files are unfortunately a fairly common issue in the Garmin ecosystem, and many users rely on repair tools such as FIT File Repair Tool or FIT File Tools to recover activity data. It would be interesting to see whether your analysis can help identify common corruption patterns across different devices and firmware versions.https://forums.garmin.com/developer/fit-sdk/f/discussion/437310/python-sdk-weight_scale-weight---potential-bug/2035633Tue, 02 Jun 2026 17:17:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:519de691-7e92-4455-8e05-454090b800eaEli FITHello, this is the correct place to raise this question. You are right that the issue is due to the weight field in the weight_scale mesg having a type of weight (enum) rather than a uint16. The weight type is a uint16 value under the hood but is interpreted by the Python and JavaScript SDKs as an enum rather than the intended numeric type. This causes both the encoder and decoder to handle the value without applying or reversing the scale/offset. For example, when encoding a weight with a decimal e.g. 85.56, the encoder will currently truncate the value to 85 rather than apply the scale of 100. 'weight': { '0xFFFE': 'calculating', }, Thanks for bringing this to our attention! We'll work on getting this fixed in both SDKs and address this post when it has been released.https://forums.garmin.com/developer/fit-sdk/f/discussion/437346/does-garmin-firstbeat-silently-track-aerobic-threshold-in-fitTue, 02 Jun 2026 13:22:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:79bfca8c-001b-48ef-a152-95d8b74c6492RinseRepeatIs it plausible on the newest Garmin watches they silently track Aerobic Threshold in the Firstbeat ecosystem? The advanced historical projected LTHR is new since Fenix7/Fenix8 since the Fenix6 Firstbeat doesn't do that Which makes me wonder if buried particularly in Run activities they are silently tracking Aerobic Threshold It cannot be done from a single run, it would have to be over several activity/weeks, so it would have to be forwarded in each FIT file Just to clarify, LTHR is actually anaerobic threshold (aka Ventilatory Threshold 2) Aerobic Threshold is sometimes rarely called "fatmax" or Ventilatory Threshold 1 aka AeT AeT is typically half of vo2max but not always depending on training/genetics I'm kinda surprised Garmin doesn't openly expose/track Aerobic Threshold as of 2026, they've practically exhausted every other metric in Firstbeat But it basically MUST silently do it since you are given an Aerobic+Anaerobic score for each Runhttps://forums.garmin.com/developer/fit-sdk/f/discussion/437310/python-sdk-weight_scale-weight---potential-bugMon, 01 Jun 2026 17:58:00 GMTa9571b57-dd57-479e-8763-8f8a603e40aa:477e7794-958a-46ca-8bcd-a660429fc3ba8294519I wrote an encoder based on the pythonSDK test_encode_activity_recipe.py. It seemed to work well except for the weight key like below: mesgs.append({ 'mesg_num': Profile['mesg_num']['WEIGHT_SCALE'], 'timestamp': scale_date, 'weight': 8400, #decoding issue? 'muscle_mass': 66.0, })Code The 'weight' is a weight type and supposed to be in kilograms; however, it seems to scale incorrectly (8400 instead of 84.0kg). The other keys that use mass (eg/ muscle_mass) all convert from to kilograms okay when uploading the FIT file to Connect. Perhaps it's a type weight vs type unit16 issue? Thoughts? Thanks! PS Hopefully I'm writing this in the correct place, apologies if not.fitsdkpythonscale