trail & handling

neeb

How noticeable is an increase in trail from around 58 to 62.5mm?

current setup - 73 head angle, 43 fork rake, 58.3 trail.

potential new setup - 72 ha, 45 rake, 62.5 trail.

The second setup would also have a wheelbase about 1cm shorter and a stem 1cm longer (100 => 110). Actual distance from top of steerer tube to hoods would be about 1.75cm longer.

I know both trail values are within acceptable limits, but I'm wondering if it would take time to adapt. Particularly thinking of 1) cornering on descents and 2) stability at cruising speeds or slightly lower speeds when taking hands off the bars to eat and drink etc.

maddog 2

I think they'll feel a bit different but, as you say, they are within limits so no real problem. I ride two roadies (not at the same time) and one is CX geometry and one is normal roadie. I can tell straight away that they are different but within a mile or so I've adapted and it's not a problem.

The potential setup has a shallower head angle (i.e. slower steering) but more rake (i.e. faster steering), so these things will cancel each other out to some extent. You may find the longer stem length and overall stretch of the potential setup has a bigger effect on the way the bike rides than the trail issue.

neeb

I think they'll feel a bit different but, as you say, they are within limits so no real problem. I ride two roadies (not at the same time) and one is CX geometry and one is normal roadie. I can tell straight away that they are different but within a mile or so I've adapted and it's not a problem.

The potential setup has a shallower head angle (i.e. slower steering) but more rake (i.e. faster steering), so these things will cancel each other out to some extent. You may find the longer stem length and overall stretch of the potential setup has a bigger effect on the way the bike rides than the trail issue.

Thanks for that. The stretch will be identical, I will be able to replicate the reach to the hoods, saddle to bar drop and saddle position relative to bottom bracket exactly. My understanding of the fork rake is that although 45mm is longer than 43 and partially compensates for the shallower head angle, the head angle will make a bigger difference, hence the overall increased trail. But I did wonder if the 1cm shorter wheelbase might further compensate for the reduced head angle when cornering.

Basically, I will have slightly more trail but my hands will be slightly further forward relative to the front hub (the reduced wheelbase is all at the front end - chainstay length will change by only 1mm).

maddog 2

basically the new bike will feel a bit smaller, even though the contact points are in the same place. It's small differences though. Think about it like going from a 23mm tyre to a 25mm - the steering is a tad slower but it's no big deal. Road bikes steer too quickly IMO anyway - blame the race bike marketing approach.