Low Trail Geometry

[Hikyle2]

Sorry to probably ask a question that's been beat to death by some, but I wanna understand more.

I have a surly cross check as a town bike with bullmoose bars and a soma porteur rack with an ILE rack bag. As you can imagine, it handles pretty poorly when even just the bag is on. I guess what I wanna know is would low trail really make the ride that much better?

I understand how low trail works and how to calculate it, but I find it hard to believe that the bike will ever be so easy to ride that i'm not having to muscle the front end because of the weight. I have debated getting a champs elysees fork as that's the cheapest fix but was just curious of opinions.

[buddybikes]

Why not traditional rear rack, rack bag and perhaps panniers?

[Old School]

"angled headset" from England might be even cheaper, and the machine work is unparalleled.

https://www.workscomponents.co.uk/15-degree-headsets-14-c.asp

[Hikyle2]

I'll be honest I like the look of a front rack, looks cleaner on the bike, and I have it at this point.

[Hikyle2]

"angled headset" from England might be even cheaper, and the machine work is unparalleled.

https://www.workscomponents.co.uk/15-degree-headsets-14-c.asp

Never heard of that, so it just changes the headtube angle? that's pretty crazy.

[spoonrobot]

Sorry to probably ask a question that's been beat to death by some, but I wanna understand more.

I have a surly cross check as a town bike with bullmoose bars and a soma porteur rack with an ILE rack bag. As you can imagine, it handles pretty poorly when even just the bag is on. I guess what I wanna know is would low trail really make the ride that much better?

I understand how low trail works and how to calculate it, but I find it hard to believe that the bike will ever be so easy to ride that i'm not having to muscle the front end because of the weight. I have debated getting a champs elysees fork as that's the cheapest fix but was just curious of opinions.

Yes, this is exactly what low trail will do because of the massively decreased flop. Riding my 35mm trail bike with 30 pounds on the front end doesn't even feel as sluggish and floppy as my 62mm trail bike with 5 pounds on the front end. 38mm trail bike with a normal load 5-10 pounds? Like it's not even there.

Have you read Fred Blasdel's writings on low-trail from back in 2013? Google his threads (on another forum so I don't wanna link) and it'll give you a better idea of what happens and why. I'd say go for it, secondary market value of the low-trail Soma forks is very good if you do not find it to your liking.

[Hikyle2]

Thanks, I hadn’t read his stuff specifically at it’s awesome. I love his reply’s to people on some post as well.

[etu]

Makes a HUGE difference to have a low trail fork if you're going to carry weight up front. I have been using a mini-porteur rack with anywhere between 5-20lbs on my commuter for the last five years and it rides incredibly well. The low trail geometry provides a stable but playful ride even without any weight, but is optimal with at least a few pounds.
Also IMO, the "liveliness" of a bike is preserved by not putting any unnecessary weight in the rear. Most people notice the downsides of the rear rack when pedaling out of saddle, but I think most of us flex our bikes side to side a little bit even when riding seated, especially on any climbs where there is additional torque. This little flex is what I would suggest as the source of the magic carpet ride. When this flex is muted through a overladen saddle bag or a rear rack, the ride quality suffers.
In the end, you'll just have to experiment and experience for yourself, but I would highly recommend it.

[HTupolev]

but I find it hard to believe that the bike will ever be so easy to ride that i'm not having to muscle the front end because of the weight.
The question is why the weight is having to be "muscled" in the first place. Even if the steering column has a lot of inertia, it's not hard to cause a bicycle to lean into a turn.

The big issue with handlebar bags is that the weight is located in a place where it puts torque on the steering column when the bike is leaned. If the bike is leaned to the right, the bag torques the steering clockwise when viewed from above; if the bike is leaned to the left, the bag torques the steering counter-clockwise when viewed from above.
This behavior is very similar to "wheel flop" caused by the steering geometry, and higher-trail steering geometries typically have more wheel flop.
In both cases, if either of these flop effects are very high, the rider might feel like they're battling against the flop when doing stuff like rocking the bike out of the saddle. "Very high" depends on the type of bike; mountain bikes tend to have high-trail geometries with tons of wheel flop, but they also use super-wide handlebars which give the rider tons of leverage over the steering axis.
Anyway, if there's too much flop due to the handlebar bag, you can compensate by using a lower-trail steering geometry to reduce the flop from the geometry.

The location of the front weight matters a lot in its effects. Panniers on lowrider racks don't tend to hold their weight way out in front of the steering axis, for instance, so well-balanced weight there can add inertia to the steering without adding flop.

[Hikyle2]

It all is starting makes sense since I’ve been riding the bike like this for over a year. The rear of the bike still behaves just as I would expect, it’s just the front end that is a worry so if I can solve that with the fork it’s definitely worth a shot. I think if anything I can then understand how it handles and if it’s ever worth getting a bike designed around it. This is just my commuter bike but I have a tendency to make every bike nicer than they might need to be.

[ColonelJLloyd]

A Surly with a high rake fork producing low-trail will still be a Surly. It will not magically transform the bike. And nothing happens in a vacuum so you will not confidently be able to say the change in fork is what made you like/dislike the result.

I would encourage you to try a bike or two that was designed out of the gate with low-trail geometry and see what it's like for you. Opinions differ greatly. I realize this is difficult to do in many cases. I bought a used low-trail bike. Then I sold it and ordered a custom one.

[spoonrobot]

A Surly with a high rake fork producing low-trail will still be a Surly. It will not magically transform the bike. And nothing happens in a vacuum so you will not confidently be able to say the change in fork is what made you like/dislike the result.

I would encourage you to try a bike or two that was designed out of the gate with low-trail geometry and see what it's like for you. Opinions differ greatly. I realize this is difficult to do in many cases. I bought a used low-trail bike. Then I sold it and ordered a custom one.

That's exactly what a low-trail fork did for me. I have a Soma Fogcutter that had 57mm trail with the stock fork. I swapped in the Soma low-trail disc fork and dropped the trail to 35mm and it's a completely different bike both with and without a front load - but moreso with. Especially on anything loose or on wet pavement.

The vast majority of frames designed around low-trail are effectively no different than those designed for mid-trail. For the OP's complaint wrt the Surly Cross Check - certainly a low-trail fork will offer the change he's looking for without other major geometry considerations:

but I find it hard to believe that the bike will ever be so easy to ride that i'm not having to muscle the front end because of the weight.

This BQ PDF is also interesting reading, one frame with three forks: http://yojimg.net/bike/kogswell/kogswell_docs/Model%20P:R/Kogswell%20PR%20brochure.pdf

[ColonelJLloyd]

That's exactly what a low-trail fork did for me. I have a Soma Fogcutter that had 57mm trail with the stock fork. I swapped in the Soma low-trail disc fork and dropped the trail to 35mm and it's a completely different bike both with and without a front load - but moreso with. Especially on anything loose or on wet pavement.

The vast majority of frames designed around low-trail are effectively no different than those designed for mid-trail. For the OP's complaint wrt the Surly Cross Check - certainly a low-trail fork will offer the change he's looking for without other major geometry considerations:


I don't disagree that a fork swap can make a night and day difference in the handling with front loads. I don't disagree with your experience or what you are effectively saying for you.

However, my overall point is in disagreement with your bolded statement. I think it's far from certain.

It likely sounds like I'm trying to be argumentative, but I'm not so I'm going to stop commenting here after saying that low-trail geometry is really one of those things that one has to try for themselves and the "feel" of it is interpreted very differently by people.

[jwin]

This may be to OT but related to low trail. I'm new here and learning so much about bikes that I never knew.

What I'm wondering is what exactly does trail do to affect the steering feel? I understand what trail is, but I can't seem to understand what the effect would be if say trail were 0mm? Your contact point is now on the steering axis - what does that feel like? What if your contact point was in front of the steering axis?

[cmg]

This may be to OT but related to low trail. I'm new here and learning so much about bikes that I never knew.

What I'm wondering is what exactly does trail do to affect the steering feel? I understand what trail is, but I can't seem to understand what the effect would be if say trail were 0mm? Your contact point is now on the steering axis - what does that feel like? What if your contact point was in front of the steering axis?

look at the diagram. As the trail gets smaller (cen of axle meets cen of fork angle ) front end becomes twitchy. bike will not center itself, can't ride no handed. As the trail increases or steering axis angle increases wheel increases it's tendency to want to flop over. bike will have a tendency to ride in a straight line. rider's weight is behind the fork normally but with a front rack center of gravity is shifted forward. Discuss

[marciero]

This may be to OT but related to low trail. I'm new here and learning so much about bikes that I never knew.

What I'm wondering is what exactly does trail do to affect the steering feel? I understand what trail is, but I can't seem to understand what the effect would be if say trail were 0mm? Your contact point is now on the steering axis - what does that feel like? What if your contact point was in front of the steering axis?

As you can guess, lots and lots has been written about this, and much from people "qualified" in some sense to give impressions worth listening to.
With regard to contact in front-that would be negative trail. The mechanical engineer (I think) Jim Papadopoulos has done a lot of work on bicycle mechanics and has demonstrated that a bike with negative trail can be ridden and balanced.

[marciero]

I like both high and low trail. They're just different. For me, a small front load on a high trail fork has not been a problem.

My nutshell summary of the difference in steering feel is that


The cutoff speed where the bike has tendency to go from oversteer to understeer is much higher on high trail.
The "on rails" feel on corners is a high trail phenom.
The flip side of the above is that the low trail waits for you to tell it where to go, and so more amenable to things like adjustments mid corner. Riders more used to high trail often describe this as the front end being "vague".

[Hikyle2]

I've heard the comment about them being vague, how they like to go in a straight line, so I'm pretty interested to see how it turns. I think the $200 fork is a pretty low barrier to entry for someone that's curious.

I have looked around for used low trail / randonneuring bikes, is there anywhere that's better to look than others? i've looked here obviously, ebay, and local to me. It seems like one of those things that only pops up occasionally that's not super spendy.

[slowpoke]

The big issue with handlebar bags is that the weight is located in a place where it puts torque on the steering column when the bike is leaned. If the bike is leaned to the right, the bag torques the steering clockwise when viewed from above; if the bike is leaned to the left, the bag torques the steering counter-clockwise when viewed from above.
This behavior is very similar to "wheel flop" caused by the steering geometry, and higher-trail steering geometries typically have more wheel flop.

Is this the definition of wheel flop? Because if it is, I actually notice more flop on my low trail bike (unloaded) than my mid/neutral trail bikes.

e.g. when I lean into into a turn on a low trail bike, the front wheel turns towards the direction of the lean. This feels like the bike will fall over. In contrast, on higher trail geometries, the bike's steering remains fairly neutral as the bike leans.

[slowpoke]

I have looked around for used low trail / randonneuring bikes, is there anywhere that's better to look than others? i've looked here obviously, ebay, and local to me. It seems like one of those things that only pops up occasionally that's not super spendy.

Check the 650b Google Group, look for old Treks (here's a list (http://sfcyclotouring.blogspot.com/2007/09/about-low-trail-and-low-trail-treks.html) by Jim G), or check Velo-Orange, Crust Bikes, or Cycles Toussaint.

[HTupolev]

Is this the definition of wheel flop? Because if it is, I actually notice more flop on my low trail bike (unloaded) than my mid/neutral trail bikes.

e.g. when I lean into into a turn on a low trail bike, the front wheel turns towards the direction of the lean. This feels like the bike will fall over. In contrast, on higher trail geometries, the bike's steering remains fairly neutral as the bike leans.
You're probably noticing a different factor.

When flop is affecting a turn, keep in mind the effects of countersteer. Torque that's trying to turn the steering farther into the turn will tend to have the effect of causing the bike to lean up and out of the turn.
(The centrifuge effect of the turn makes the whole situation kind of complicated, though.)

Wheel flop is something that people usually notice most directly when rocking the bike at low speeds out of the saddle.

[unterhausen]

I always thought that flop was misnamed. It's the amount that the head tube drops as you turn the fork. I really have to ride my high-trail gravel bike a lot before I'm comfortable standing out of the saddle. OTOH, numerically low trail bikes still have some flop. I have noticed a little bit of self steering when cornering with my low trail bike. It doesn't bother me, but I know some people don't like it. The self-steering is not caused by flop.

My general impression is that low trail bikes are floppier in the conventional meaning of the word.

[slowpoke]

I always thought that flop was misnamed. It's the amount that the head tube drops as you turn the fork. [...] I have noticed a little bit of self steering when cornering with my low trail bike. It doesn't bother me, but I know some people don't like it. The self-steering is not caused by flop.

Thanks! I did look up wheel flop later and came across the same definition as you've posted. I guess the term describing the phenomenon I experience may be "self-steering".

Some folks tell me that this may be due to wider tires having more grip, but I'll need to experiment more.

[unterhausen]

it's not the tires, I took the exact same wheel/tire combo off the previous bike which did not exhibit this tendency and put it on the low trail bike, which did.

[colker]

Would a 26in mtb be low trail? 71 degr. headset and 1.75in rake...

[HTupolev]

71 degr. headset and 1.75in rake...
A 71-degree head angle and 44mm of offset on 2" 26er tires would be around 69mm of trail. That's very low by MTB standards, but high by road standards.

MTBs generally have more trail than road bikes. There are a few interrelated factors here, the most obvious being the wider handlebars: the higher leverage that the rider has on the steering sort of "cancels out" the increased floppiness at low speed and stiffening at high speeds.

Would a 26in mtb be low trail?
Depends. 26er mountain bikes were made over a very long time span, during which geometry was constantly evolving.
Most early-80s MTBs were still based closely on the Repack "klunkers", which were largely beach cruisers employed for downhill duty. Trail figures were often 80mm or more, and the chainstays were absolutely enormous, often in the 470mm+ ballpark.

[marciero]

I always thought that flop was misnamed. It's the amount that the head tube drops as you turn the fork. I really have to ride my high-trail gravel bike a lot before I'm comfortable standing out of the saddle. OTOH, numerically low trail bikes still have some flop. I have noticed a little bit of self steering when cornering with my low trail bike. It doesn't bother me, but I know some people don't like it. The self-steering is not caused by flop.

My general impression is that low trail bikes are floppier in the conventional meaning of the word.

I'd sort of agree. At low to moderate speed if you jerk the steering back and forth quickly-more like shaking than steering-there is a noodly or "floppy" feel compared to high trail bikes, which dont feel that way at all. Of course, they are more prone to shimmy, which is probably related. And it's going to be related to the wheel flop too. The greater the wheel flop, the less floppy

[slowpoke]

Would a 26in mtb be low trail? 71 degr. headset and 1.75in rake...

Most likely not. Use Jim G's trail calculator to check, though!

http://www.yojimg.net/bike/web_tools/trailcalc.php

[colker]

Most likely not. Use Jim G's trail calculator to check, though!

http://www.yojimg.net/bike/web_tools/trailcalc.php

You are right: it´s quite high.

[Doug Fattic]

I have looked around for used low trail / randonneuring bikes, is there anywhere that's better to look than others? i've looked here obviously, ebay, and local to me. It seems like one of those things that only pops up occasionally that's not super spendy.I have in my shop a 1949 Claud Butler. One day I decided to throw it on my fixture to discover its geometry. I was surprised it has a head angle of 74º with a fork rake of 2 3/4" (the British weren't into metrics back then). Until I measured this frame, I thought low trail frames were mostly a French thing. I think the owner paid only a few hundred dollars for it on eBay.

Don't confuse the Claud Butlers made before 1957 with frames branded with that name made afterward. Claud went into bankruptcy and the name was sold and made by Holdsworthy after that. Some of the UK's best builders got their start at CB just before and after WWII like Bill Hurlow and Ron Cooper among others. Butlers in the golden age after the war were famous for their bilaminate "half lugs" made from flat plate.

[NHAero]

I'd like to resurrect this thread to help me think about the bike I'm having designed and built by Carl Strong. Carl so far has been the ideal collaborator - he listens carefully to input and has a firm hand on the design. However..

My head is swimming from reading about geometry for road bikes with fatter tires at low pressures. In particular, low trail etc. I have a pal in Seattle who rides 38 and 42 tires in both 650b and 700c and he is urging me to a front end geo with trail in the mid-30s. One of the points he notes is that tire pressure has a large effect on handling with low pressure chubby tires (let's say 650bx38-42, at 35-40 psi?) and when he has done mixed pavement and gravel rides he stops and changes the tire pressure. I have no experience between 700x37 tires at 55 psi and 559x2.2 tires at 25-35 psi, and the latter is a converted MTB so it has a suspension fork and super minimal BB drop so not that useful to compare.

I ride with a handlebar bag and this bike will have it also. With the normal stuff in it (spare tube, minipump, tools) it weighs about two pounds. Certainly possible to get that up over five pounds when it's packed. That bag goes onto 4 bikes. It has the least effect on handling on the two with 74 HTA and 48mm trail, and 73 HTA and 50mm trail. But these bikes aren't chubsters in the tire dept.

I've been reading the Blasdel posts referenced above. I'm looking for a road bike that can go on New England dirt roads, not on the rough loose gravel people are riding out west. Back in the day before I knew any better I rode the Bob Jackson on these roads all the time, with 25-32mm tires, always at high pressure (and I'm 140 pounds). I've learned from the bike with 700x37 that low rolling resistance fatter tires make that riding easier. But I am not looking for what people call a gravel bike, or a bike that can take a porteur rack and deliver cases of beer on it. BITD when I toured on my Bob Jackson, I had a bar bag and front panniers (before low riders existed) and put heavy stuff in the front panniers and light stuff on the rear rack and panniers. It all worked fine but maybe I was too unaware to notice :-) The thing is, that bike handled fine when it was stripped and running lightweight tubulars too. 73 HTA, 50mm trail. But always high pressure in the tires, even when I ran 32s (duh but I didn't know)

I have geo sheets on two similar bikes from generous fellow PLers. One is Sparky33's lovely Firefly, the other is Doomridesout's custom Seven. Both designed around 38-42 tires in a road configuration. Both using the Whisky Road Plus fork I am planning to use, with an offset of 51mm. Yields trail of 51 and 53mm with HTAs of 72.5 and 72.2. I know I have a bias towards steeper HTAs from all the bikes I have and have owned.

So - will a HTA of 73 and a trail of 48-50mm work with these 38-42mm tires at the low pressures people run them at (tubeless, carbon rims)? My Seattle friend says no, the bike will handle poorly on pavement. To achieve significantly lower trail means a custom steel fork because carbon forks don't come in low trail geo (not enough offset).

Second order question - if I start with a carbon fork that has a 1-1/2" tapered fork, and I want to put a 1-1/8" steerer fork in to replace it, will there be a headset solution that fits into the 44mm head tube?

Thanks for reading!

[bicycletricycle]

Interesting article on wheel flop-
https://kuromori.home.blog/what-is-wheel-flop/

[Bici-Sonora]

First, you are going to be riding this nice new Strong custom, not your friend from Seattle, so yours is the opinion that matters. If it were me, I would not order a custom with a geometry that I wasn't intimately familiar with and comfortable on. You need to ride some bikes with different trail numbers so see what you like. There is no other way IMO. My three favorite bikes have vastly different trail figures. I love them all, but they are very different.

Low trail. My MAP has a 73 HTA, with 65mm of offset. I run 650b x 42mm tires for a mech. trail of 34. It has a front bag, that always has a couple of pounds of stuff in it, and provisions for low-riders when touring. It handles way differently in corners than the other bikes I'll list below. I adjust to it in about 10 seconds when switching between bikes. I like low trail on this kind of bike, but even with a roller bearing headset, on big bikes, so some shimmy may be part of the deal. No hands riding can be tricky depending on speed and how the bags are loaded. Easy to change your line mid-turn.

Mid Trail/Neutral: Kirk MRB (Clean's) 73.5HTA 43mm offset, Trail is 54 with 30mm tires. Classic mid trail/neutral road race geo--quick but not twitchy, stable but still maneuverable and sporty. No hands riding is easy.

Higher end of Mid Trail/Neutral: Ritchey Ascent 71HTA 52mm offset, Trail is 59 with 48mm tires. Super stable, a bit harder to change direction mid turn than the Kirk. By far the most stable of the three for no-hands riding. Also stable with Swift La Paloma bag with around 5lbs in it.

[unterhausen]

That is an interesting article. To me, the idea that a front load is better balanced with respect to the steering axis on a low trail bike is pretty compelling. But the article also shows that bicycling is full of b.s. and I shouldn't trust anything that people "know."

I think there is probably something in those calculations that can be teased out to explain some of the differences in low trail and high trail.

[Bici-Sonora]

So - will a HTA of 73 and a trail of 48-50mm work with these 38-42mm tires at the low pressures people run them at (tubeless, carbon rims)?
Thanks for reading!

You may already know about these (or maybe they were called out earlier in the thread: TLDR:), but you can play with bike geometry and trail in Bike Insights (link to geo of two of my bikes referenced above): https://bikeinsights.com/compare?geometries=5d4210893253c30017a9675d%2C5f0c b2fca8c734001787910b&builds=5f232fc02f5f0200172df23b%2C5f0cbd55a8c73400 17879110

And the trail calculator:http://yojimg.net/bike/web_tools/trailcalc.php

[NHAero]

Didn't know about the Bike Insights page, that looks very cool.
I've measured some of my bikes very carefully (mount in a home made stand that holds the rear wheel, and push the rear tire against the wall) by taking horizontal and vertical measurements, so at least I have a good idea of what I'm already riding. I have noticed that the measurements don't always conform to the build sheets, either!

You may already know about these (or maybe they were called out earlier in the thread: TLDR:), but you can play with bike geometry and trail in Bike Insights (link to geo of two of my bikes referenced above): https://bikeinsights.com/compare?geometries=5d4210893253c30017a9675d%2C5f0c b2fca8c734001787910b&builds=5f232fc02f5f0200172df23b%2C5f0cbd55a8c73400 17879110

And the trail calculator:http://yojimg.net/bike/web_tools/trailcalc.php

[Mark McM]

THere are a number of dynamics that affect the stability of a bicycle, including flop, castor, trail, etc. When you add a weight to the handlebars, you accentuate a lesser known dynamic of bicycle stability, called the Two Mass affect.

As we all know, a bicycle stays upright by continuously steering the the front wheel into the direction of lean, which (as long as the bike is moving forward) causes the wheel contact points move back under the bike's CG, keeping it balanced But how does it do that steering without rider input? Trail and flop are one way, but differences in the moment of inertia of the frame and fork is another. When a bike falls over, it is basically rotating around an axis at the tire ground contact points. The rate it falls will related to its moment of inertia, which is largely affected by the distance from the ground to the CG - a taller bike falls slower. But another interesting thing happens when the bike starts to fall to the side - if the CG of the fork assembly is offset from the steering axis (as when there is a bag mounted in front of the handlebars), this weight will also fall in the direction of lean, which can turn the fork into the direction of lean. Because the CG of the weight on the fork is closer to its axis of rotation (the steering axis), the fork has a lower moment of inertia when turning on the steering axis than the entire bike does when it is falling over, so the bike will steer in the direction of the fall faster than the bike can fall over - and thus re-balance the bike before it can fall over. This is a large part of the reason that bikes with heavy bags and racks behave better with low trail - because the Two Mass affect can provide stability without adding excessive flop.

The Two Mass affect is described in this video:

https://www.youtube.com/watch?v=84Wczsi4vHg

[OtayBW]

I'd like to resurrect this thread to help me think about the bike I'm having designed and built by Carl Strong. Carl so far has been the ideal collaborator - he listens carefully to input and has a firm hand on the design. However..

If you're getting a road bike with 700c wheels, I would be very cautious about a trail in the mid-30s. I would think your discussion with Mr. Strong should start from something in the neutral (~55-57) range and go from there... GL

[NHAero]

If I boil it down, I think the question I'm looking to answer is, does riding a 38-42mm tire at low pressures work better with low trail than a front end geo I already know I prefer? Steep enough HTA (73 or more) and (I guess) low end of mid-trail (48-50mm). I have plenty experience with this geo, but not with low pressure tires. Thanks!

First, you are going to be riding this nice new Strong custom, not your friend from Seattle, so yours is the opinion that matters. If it were me, I would not order a custom with a geometry that I wasn't intimately familiar with and comfortable on. You need to ride some bikes with different trail numbers so see what you like. There is no other way IMO. My three favorite bikes have vastly different trail figures. I love them all, but they are very different.

Low trail. My MAP has a 73 HTA, with 65mm of offset. I run 650b x 42mm tires for a mech. trail of 34. It has a front bag, that always has a couple of pounds of stuff in it, and provisions for low-riders when touring. It handles way differently in corners than the other bikes I'll list below. I adjust to it in about 10 seconds when switching between bikes. I like low trail on this kind of bike, but even with a roller bearing headset, on big bikes, so some shimmy may be part of the deal. No hands riding can be tricky depending on speed and how the bags are loaded. Easy to change your line mid-turn.

Mid Trail/Neutral: Kirk MRB (Clean's) 73.5HTA 43mm offset, Trail is 54 with 30mm tires. Classic mid trail/neutral road race geo--quick but not twitchy, stable but still maneuverable and sporty. No hands riding is easy.

Higher end of Mid Trail/Neutral: Ritchey Ascent 71HTA 52mm offset, Trail is 59 with 48mm tires. Super stable, a bit harder to change direction mid turn than the Kirk. By far the most stable of the three for no-hands riding. Also stable with Swift La Paloma bag with around 5lbs in it.

[Bici-Sonora]

If I boil it down, I think the question I'm looking to answer is, does riding a 38-42mm tire at low pressures work better than a front end geo I already know I prefer? Steep enough HTA (73 or more) and (I guess) low end of mid-trail (48-50mm). I have plenty experience with this geo, but not with low pressure tires. Thanks!

Not necessarily better, but for sure a mid 30s trail number will feel different than something mid to upper 50s. For your use case scenario (smooth east coast dirt), it seems to me that a low-trail bike built around 650b x 42mm range (I run mine at ~40psi) will be a really comfortable bike that will handle a bit of front loading well. My MAP is great at that and feels sporty enough for everything except knives out group rides. However, there are some on this list who (thinking of you PCB!) who strongly dislike low-trail handling. I'm more agnostic. I wouldn't want all my bikes to be low-trail though. One is enough:)

I always enjoy your posts and know you have a lot of experience with different bikes. I didn't mean to imply you were an amateur.

[pbarry]

+1
You need to figure this out on the ground before signing off on the geo, (I'd be surprised if CS would build the low trail unless you were regularly carrying serious weight up front).
Get some wide tires and run em low pressure on pavement on whatever bike you have that will fit the width you're after.
Beware of the rabbit hole of advice from strangers/your buddy in PNW, (and mine!). Carl knows his stuff, ya gotta trust the builder. :)

First, you are going to be riding this nice new Strong custom, not your friend from Seattle, so yours is the opinion that matters. If it were me, I would not order a custom with a geometry that I wasn't intimately familiar with and comfortable on. You need to ride some bikes with different trail numbers so see what you like. There is no other way IMO. My three favorite bikes have vastly different trail figures. I love them all, but they are very different.

Low trail. My MAP has a 73 HTA, with 65mm of offset. I run 650b x 42mm tires for a mech. trail of 34. It has a front bag, that always has a couple of pounds of stuff in it, and provisions for low-riders when touring. It handles way differently in corners than the other bikes I'll list below. I adjust to it in about 10 seconds when switching between bikes. I like low trail on this kind of bike, but even with a roller bearing headset, on big bikes, so some shimmy may be part of the deal. No hands riding can be tricky depending on speed and how the bags are loaded. Easy to change your line mid-turn.

Mid Trail/Neutral: Kirk MRB (Clean's) 73.5HTA 43mm offset, Trail is 54 with 30mm tires. Classic mid trail/neutral road race geo--quick but not twitchy, stable but still maneuverable and sporty. No hands riding is easy.

Higher end of Mid Trail/Neutral: Ritchey Ascent 71HTA 52mm offset, Trail is 59 with 48mm tires. Super stable, a bit harder to change direction mid turn than the Kirk. By far the most stable of the three for no-hands riding. Also stable with Swift La Paloma bag with around 5lbs in it.

[Bici-Sonora]

Didn't know about the Bike Insights page, that looks very cool.

One thing I really like about Bike Insights is that you can visually see the geometry of highly regarded production bikes in your size (Moots Routt RSL, or Rivendell Quickbeam, for example) and see the stack/reach/trail, and a graphical representation of each frame overlaid against a bike whose geo you have experience with. You can also enter customs if you have build sheets.

[NHAero]

I have a lot of faith in Carl, not to worry.
I think a customer is a better partner the more they are informed about the consequences of what they may be asking for. originally I thought that because I wasn't asking for a "quiver killer, Swiss Army" bike that this would be fairly straightforward. I'm not intending to carry a lot up front. I'm not aksing for 27.5 x 2.1 knobbies. Since a 650bx38-42 isn't too far from the diameter of a 700cx25, I thought to stick to the geo of the bikes I like best. I hadn't thought about the different pressures making a big impact. And maybe they don't!


+1
You need to figure this out on the ground before signing off on the geo, (I'd be surprised if CS would build the low trail unless you were regularly carrying serious weight up front).
Get some wide tires and run em low pressure on pavement on whatever bike you have that will fit the width you're after.
Beware of the rabbit hole of advice from strangers/your buddy in PNW, (and mine!). Carl knows his stuff, ya gotta trust the builder. :)

[Bici-Sonora]

If I boil it down, I think the question I'm looking to answer is, does riding a 38-42mm tire at low pressures work better than a front end geo I already know I prefer? Steep enough HTA (73 or more) and (I guess) low end of mid-trail (48-50mm). I have plenty experience with this geo, but not with low pressure tires. Thanks!

That low end of mid-trail seems kind of like a no-man's land of trail. There are a lot of classic road bikes with trail numbers from 53-61, and a fair number of low trail randos in the 32-40 range, but seemingly not many bikes in between.

Velo Orange made a 700c rando bike in 2010 with a 73HTA, 55mm offset and 46 trail with 28mm tires. A current production bike would be the Fairlight Faran, with a 72.5HTA 60mm offset and trail of 44mm with 650b x 47mm tires.

Maybe the easiest low-trail bike to find used would be a Velo Orange Polyvalent. The tubeset is stout but it would give you a good idea of how a low trail 650b x 42mm bike with 35 of trail handles.

[NHAero]

I had thought that old classic road bikes commonly had the geo my 1972 Bob Jackson has - 73 HTA, 50mm fork offset, 50mm trail with a 700cx24 tire. Bigger bikes might have a bit less trail from steeper HTA, and smaller bikes the opposite.

That low end of mid-trail seems kind of like a no-man's land of trail. There are a lot of classic road bikes with trail numbers from 53-61, and a fair number of low trail randos in the 32-40 range, but seemingly not many bikes in between.

Velo Orange made a 700c rando bike in 2010 with a 73HTA, 55mm offset and 46 trail with 28mm tires. A current production bike would be the Fairlight Faran, with a 72.5HTA 60mm offset and trail of 44mm with 650b x 47mm tires.

Maybe the easiest low-trail bike to find used would be a Velo Orange Polyvalent. The tubeset is stout but it would give you a good idea of how a low trail 650b x 42mm bike with 35 of trail handles.

[pbarry]

If there’s a builder near you, or you could ship it to them, this would be your easiest mock up solution. Not a big job for someone who builds forks.

[R3awak3n]

already answered but I would not order a low trail bike without first having tried it. Some people are not a fan, some believe that you need a load in the front for the bike to behave properly, ect.

I have had a couple of low trail bikes the latest one was my elephant NFE. Although there were somethings about that bike I did not like, the trail was not one of them, I even rode the bike with no front rack or even load (just a small burrito bag) for the last months of ownership and I loved the way it handled. I am a fan of low trail geo and agree that you can put a nice load up front and the bike still rides as it should, its pretty cool.

I just bought a low trail bike a month or so ago, still have not really ridden it, just finished building it and way too cold out there (yes I am a wuss this year). This one has skinny tubes though so should ride different than the elephant (hopefully the tubes is what made the elephant not that interesting of a ride and what will make this bike better along with the low trail).

I am not sure where you are, I take it probably NH ahha and it is covid and all so maybe too far and you be welcome to try the bike and see if you like it. Its a 58.

I do agree, even though I like the way low trail handles not loaded, if I was not going to use a rack or a bag up front I would probably not go low trail either.... the forks do look beautiful but you are probably going disc and I think Id prefer a straight fork.

[NHAero]

I'm curious how people here define high, mid, and low trail ranges.

[twowheeledtexan]

The only thing low trail means to me is speed wobble. I’ve had a couple low trail bikes and couldn’t take my hands off the bars. However all my Rivs and Surly’s rode fine no handed and never had speed wobble. I had a Surly LHT fully loaded up front able to ride like it was on rails downhill at 40 mph with a load, no hands, no shutter, nothing. Just perfectly where I wanted it. I’ve never experienced a difficult to steer bike, but I have had bikes that couldn’t steer themselves and they were low trail.

[R3awak3n]

The only thing low trail means to me is speed wobble. I’ve had a couple low trail bikes and couldn’t take my hands off the bars. However all my Rivs and Surly’s rode fine no handed and never had speed wobble. I had a Surly LHT fully loaded up front able to ride like it was on rails downhill at 40 mph with a load, no hands, no shutter, nothing. Just perfectly where I wanted it. I’ve never experienced a difficult to steer bike, but I have had bikes that couldn’t steer themselves and they were low trail.



yeah this does seem like a problem on some bikes for sure. I had no wobbled on my elephant, ok, maybe if the front bag was super packed and I was going super fast but for most of the times there was no speed wooble... I have to say, judging a bike by not having speed wobble with no hands at 40 mph is just not a good way of doing it. If you are going that fast, you should have your hands on the bars and I never had any wooble with hands on the bar which is all it mattered to me.

[prototoast]

I'm curious how people here define high, mid, and low trail ranges.

I don't think the terms are particularly well-defined, but as a rule of thumb, I've heard <50 => low trail, 50-60 => medium trail, >60 => high trail.

[bicycletricycle]

I think it is easy to get caught up in this stuff. I certainly do. A lot of people are riding these types of bikes with higher trail numbers and having a lot of fun. Lower trail has some advantageous but with the risk of some shimmy, not sure it is is worth the risk.

[elladaddy]

The trail is mid thirties.

When I rode it with 650bx48s (36mm trail), I wasn't too pleased it's unweighted handling. But I was able to load it down with about 35 pounds and do some significant off road riding. Also descended mountain roads admirably. Mind you, I *hate* having weight on the fork. I find it almost offensive. Yet I could still marvel at the rideability with heavy weight. And no bike handles well with 20+ pounds of weight on it

I recently replaced the 48s with 42s (lowering the trail to 34mm) and shorted my stem 10mm. One of those things fixed the unweighted handling, which is now fine. I'm not sure how it will take weight now.

If getting a low trail bike, I highly recommend considering a lightweight frame. My bike (an Elephant) is very stout to handle rear weight as well and like all bikes built to handle big rear pannier loads, the ride is stiff, even with the 48s. One of the beauties of low trail is the ability to put most of the weight in front and have a rear triangle that will soak up the bumps.

[elladaddy]

I always thought that flop was misnamed. It's the amount that the head tube drops as you turn the fork. I really have to ride my high-trail gravel bike a lot before I'm comfortable standing out of the saddle. OTOH, numerically low trail bikes still have some flop. I have noticed a little bit of self steering when cornering with my low trail bike. It doesn't bother me, but I know some people don't like it. The self-steering is not caused by flop.

My general impression is that low trail bikes are floppier in the conventional meaning of the word.

I agree! It's unmistakable. I've coined this behavior "dive" to differentiate it from "flop"

[NHAero]

Thank you for this response.
What pressures were you running on the 48s vs the 42s?

The trail is mid thirties.

When I rode it with 650bx48s (36mm trail), I wasn't too pleased it's unweighted handling. But I was able to load it down with about 35 pounds and do some significant off road riding. Also descended mountain roads admirably. Mind you, I *hate* having weight on the fork. I find it almost offensive. Yet I could still marvel at the rideability with heavy weight. And no bike handles well with 20+ pounds of weight on it

I recently replaced the 48s with 42s (lowering the trail to 34mm) and shorted my stem 10mm. One of those things fixed the unweighted handling, which is now fine. I'm not sure how it will take weight now.

If getting a low trail bike, I highly recommend considering a lightweight frame. My bike (an Elephant) is very stout to handle rear weight as well and like all bikes built to handle big rear pannier loads, the ride is stiff, even with the 48s. One of the beauties of low trail is the ability to put most of the weight in front and have a rear triangle that will soak up the bumps.

[elladaddy]

Thank you for this response.
What pressures were you running on the 48s vs the 42s?

I had my 48s at 24# and it rode great, but steered less than great. 48mm Gravelkings are rather stiff, I think.

My 42mm Hetres are new, I bought the bike with them so I haven't measured the air, but it felt like about 55. I lowered it quite about, I'd say it's around 40-45 which has given it a kind of "on ice" feel..

[elladaddy]

I had my 48s at 24# and it rode great, but steered less than great. 48mm Gravelkings are rather stiff, I think.

My 42mm Hetres are new, I bought the bike with them so I haven't measured the air, but it felt like about 55. I lowered it quite about, I'd say it's around 40-45 which has given it a kind of "on ice" feel..

I should say, the 55# gave it the "ice" feeling. At the lower pressure, it's more neutral.