How much trail is too much?!

[ghisallo-bda]

Ever wondered about the optimum trail number for you? I did for a long time. I posted here and asked for advice. The Jerk and Mr Kirk posted with good advice as did many others and I thank you all.


Well I tried a change. I went from a 50mm fork with a 72deg hta to a 45mm raked fork. The trail went from 5.56cm to 6.09cm. The steering felt good with the 50 fork but I wondered if it might be just a little better with the 45. I have always heard of the euro pros having much trail to give them great stability and handling.

Well in short, the 45mm fork made the bike ride like a dog! The front wheel wanted to really wander around at lowish speed and whenever I got out of the saddle the bike felt like it would wander away from me as I stood. It felt okay at a high speed but not enough to offset the really wierd feelings at lowish speeds.

So be careful when fiddling with your steering geometry. I had always heard that the ideal trail was 5.5 to 6.1 cm. I guess I favour the lesser 'ideal' trail figure.

Despite all this I can't be too bummed as I am further along the path to knowing EXACTLY how I like a bike and why!

Again many thanks to all those who offered their advice.

[victoryfactory]

After telling Kelly that I wanted my new Legend to have very stable handling, he increased my trail to 6.42 and seatstay to 42
The result? the bike feels rock solid, so far so good
VF

[Peter]

I had a bike with a 72.5 head angle and 47mm of rake, for 57mm of trail. It felt like the bike did not want to turn or the headset was pitted. It didn't drive me nuts but it was less than ideal FOR ME.

So, when I was hit by a car and had the front end rebuilt, I asked the repairperson (different brand than the framebuilder) to give me a 73 head angle and 50mm of rake, for 51mm of trail.

I VIOLATED THE CARDINAL RULE OF SCIENCE: WHEN TESTING A HYPOTHESIS, CHANGE ONLY ONE VARIABLE AT A TIME.

My result was a bike that felt like it was on caffeine and it definitely needed your attention all the time. It was fun, and certainly rideable, but when I put a load on the rear rack such as panniers, and I did that daily, then the bike was still rideable but no-handed riding was off limits. The bike now had the shakes.

I relented after a few months and figured I had to get a new fork built with less rake. The repairperson said no; it's acceptable to bend the blades back 5mm to reduce the rake; any more than that and he'd recommend a new fork. So I brought the fork in and 10 minutes/$20 later I was out the door.

Quelle difference! 73 head angle/45mm rake/56mm trail.

The steering was tamer and the shakes when loaded were gone as well.

My experience coincides with what I've read; 55-57mm of trail seems to be the sweet spot for a road bike.

[Louis]

Grant Petersen did some extensive testing and wrote about the results in RR #31 (just out). You may want to check that out.

(To anyone who hasn't read one, I heartily recommend the Rivendell Reader. It’s a great antidote to the racer-boy stuff that tends to dominate in some cycling circles. Not that one would not be able to race a Rivendell product, but most folks don’t think of them as that type of bike.)

Louis