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Discussion Starter · #1 ·
I have a 2019 salsa Fargo that I built in late 2018. It came with a carbon fire starter fork which I ended up ruining so I had to put a steel fork on it. The carbon fire starter fork specs at a 45 mm offset and a 483 mm axle to crown. I ended up putting a surly krampus fork on with a 483 mm axle to crown and a 47 mm offset. Salsa and surly both assured me this fork would work just fine but it might make the bike just a tad bit twitchier but they said I probably wouldn't notice much. I recently changed headsets from an external to an internal on the lower so I was playing around this morning and decided to see what my trail measurements were. I did this because while setting up new Jones bars I was taking it for a ride around the block and I noticed that it had a lot of wheel flop at slower speeds. I used an online trail calculator. I measured the head tube angle at 68° which falls close to what salsa claims on their website. I punched in the 47 mm offset and my wheel size which is 29x2.6. I was shocked to get a trail reading of 103 mm! I punched in the specs for the carbon fork and it was a 105 mm! Am I missing something here? I always thought that most bikes on the market were anywhere from 50 to 80 mm of trail? This just seems extremely high but it's in the ballpark with what it was the day I purchased the frame and fork. I figured this was the appropriate forum to ask this question even though this is a production frame.
 

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Just a matter of updating your trail numbers to reflect current mtb geometry. To be sure, most drop bar road and gravel bikes still fall in that 50-80 trail range as well as some old school classic XC mtbs like my 2011 Giant Anthem which has a trail in the 70s. New XC mtbs with "progressive" or modern XC geometry, though, now run in the high 80s and 90s and, of course, trail, all mountain, enduro and downhill mtbs run higher trail numbers. Even the current Fargo with a 69 degree HTA and 51mm offset running standard 2.25 mtb tires now runs in the upper 80s. No way will you get under 100, though with 68 degrees HTA, 47mm offset on the fork and 2.6" tires. Going back to the 51 offset fork and running 2.2 or 2.25 tires would drop it below 100.
 

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Discussion Starter · #3 · (Edited)
Just a matter of updating your trail numbers to reflect current mtb geometry. To be sure, most drop bar road and gravel bikes still fall in that 50-80 trail range as well as some old school classic XC mtbs like my 2011 Giant Anthem which has a trail in the 70s. New XC mtbs with "progressive" or modern XC geometry, though, now run in the high 80s and 90s and, of course, trail, all mountain, enduro and downhill mtbs run higher trail numbers. Even the current Fargo with a 69 degree HTA and 51mm offset running standard 2.25 mtb tires now runs in the upper 80s. No way will you get under 100, though with 68 degrees HTA, 47mm offset on the fork and 2.6" tires. Going back to the 51 offset fork and running 2.2 or 2.25 tires would drop it below 100.
The original fork was not 51°, offset. The original fork from what I can find on online was 45 mm of offset. So this replacement forks a couple millimeters higher so this tells me that originally right out of the box this bike always had these kind of trail numbers. I never calculated it before and so I was just shocked to see this today
 
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