Riding long distance on various cycles I have learned a few things about how a bike handles, how to be comfortable, and a notion of what planing might be. Rather than spend some time on a dear diary ride report or a lampoon of the alleged leaders of my past time, casual distance cycling, I will attempt to share something that might be useful to others and help them understand some of the more subtle aspects of cycling.

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Geometry, low trail vs high trail

The difference between a low trail and a high trail cycle can be as little as a thumb width, but even a thumb width in fork rake or chainstay length can make a significant difference in the way a cycle reacts under a rider.

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 Bicycles turn, when moving at a speed higher than a running pace (10mph) by leaning, not by turning the handlebars. Riders instinctively do this when they employ the technique of riding with their chin pointing where they want to go or simply looking where they want to go. Deliberately using body weight to turn a cycle is known as steering with your hips. High trail cycles resist the lean of the cycle and through caster in the geometry (like the front wheels on a shopping cart) the high trail cycle is designed to self-right and not lean very easily. To counter the self-righting action of the caster the rider will place a fair amount of weight on the inside handlebar when turning (I call this ‘pushing the front’).

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 Low trail cycles do not have as much caster in the geometry, are not self-righting, fall easier, and thus turn easier. To damp the easy turning of a low trail cycle, the weight of handlebar bag works nicely, and is handy to carry things too.

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 A low trail cycle also counteracts the gyroscopic effect of a large 40MM+ heavy tire when turning. A heavy tire will cause the cycle to track straight, rather than lean or turn. High trail cycles with heavy tires (or heavy front loads) can counteract the gyroscopic effect (or the weight of a load) with wider handlebars.

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 Low trail cycles do not react to steering inputs at low speeds compared to a high trail cycle. One way to notice this is watching cyclists start riding from a stop light. A low trail cycle will tend to track straight, while a high trail cycle will tend to track from side to side as the cyclist gains speed and stability. This phenomena is also quite apparent when cycling in a group at night and climbing a steep hill. Riders on high trail cycles will oscillate from side to side and the light from their head light will move from side to side. A low trail cycle will not oscillate, and will have a more steady beam on the road.

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 Here is a link to calculating the geometric trail of a cycle.

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Geometry, chainstay length

Shorter chainstays (15 to 20mm shorter) make for better climbing off road, and allow a rider to stand and still maintain traction. Shorter chainstays also result in a more abrupt chain line and will limit some gearing combinations, particularly the small x small combinations if the big ring is fitted with ramps and pins. To gain a few more gears in the small x small combination, turn the big ring around so the ramps and pins are on the outside.

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Geometry, wide handle bars vs. narrow bars

Wide bars allow for counteracting the self centering of a high trail cycle, but there are some side effects to a wide bar. More wind resistance; wide bars place your arms out in the wind, slowing the cycle. More perceived frame flex; wide bars have more leverage and can reduce the perceived lateral stiffness of a frame, particularly when carrying heavy loads. Increased reach to the bars; wider bars often require a switch to a shorter stem, to compensate for the increased reach out to the ends of the bars.

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Narrow bars are best used on low trail cycles as low trail cycles rely less on handlebar inputs for steering and more on body weight movements. Benefit of narrow bars are better aerodynamics and less perceived frame flex – that is, a cyclist can employ a frame with lighter tubes and not overwhelm the frame as easily because of the reduced leverage of narrow bars. Narrow bars will also cause a heavily loaded cycle to feel less flexible for the same reason, reduced leverage against all the weight.

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A touring cycle with low trail, narrow bars, with a front biased load will allow lighter tubes to perform more effectively, and feel more stable than a cycle with high trail, stout tubes, wide bars and a rear biased load.

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 Geometry, fitting handlebar bags and front platform racks

Handlebar bags, or the weight on a platform rack, should fit within the space roughly between the head tube and the front axle of the cycle. Placing the load in this area damps oscillations of the front wheel also known as speed wobbles and results in a more stable cycle when loaded than when not loaded. Placing the bag more forward or centering the handlebar bag over the front axle will not allow the load to damp oscillations and will reduce stability of a cycle and exaggerate steering inputs and make it harder to compensate for exaggerated steering inputs.

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low trail cycle with optimal load carrying space indicated with red box. A ten pound load can be carried in this space without negative effects on handling or stability.

low trail cycle with optimal load carrying space indicated with red box. A ten pound load can be carried in this space without negative effects on handling or stability.

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Low trail cycles with slack frame angles and the resulting increase in fork rake necessary for low trail, will have a larger space for a handlebar bag without negatively effecting steering inputs than a low trail cycle with steep frame angles. Low trail cycles with steep angles, with a smaller ideal load carrying space, require thoughtful rack selection and load placement to not upset handling balance. Berthoud bags which are narrow front to rear are suited to cycles with steep angles; most other bags that are deeper front to rear (ostrich, jitensha) are suited to low trail cycles with slack frame angles.

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high trail cycle with platform rack. load is well in front of axle.  A heavy load on this rack will exaggerate steering inputs and resulting corrections, causing instability. Looks cool, though.

high trail cycle with platform rack. load is well in front of axle. A heavy load on this rack will exaggerate steering inputs and resulting corrections, causing instability. Looks cool, though.

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Low trail cycles have a relatively large space for a bag. High trail cycles have little or no space and place much of the bag and its weight forward of the front axle. Weight forward of the axle exaggerates turning inputs and will result in an unstable cycle. Wider bars on a high trail cycle with a front load will reduce the influence of a front load, but at the expense of poor aerodynamics, increased reach, and more perceived flex in the frame.

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1950's French purpose-built cycle for front loads still places load too far in front of axle, but compensates with wide handlebars for leverage.

1950’s French purpose-built cycle for front loads still places load too far in front of axle, but compensates with wide handlebars for leverage.

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Top tube length also influences space for a handlebar bag indirectly. A shorter top tube, with the resulting longer stem length required for fit, results in a smaller space for a bag.

Review the first image and imagine the stem longer. The resulting space left for load carrying is smaller.

Review the first image and compare with this one with the stem made longer. The resulting optimal space left for load carrying is smaller.

For maximum space for a handle bar bag, a longer top tube and shorter stem is desirable. Generally the easiest way to get a long top tube on a cycle is to move one size up from what you might normally be fitted to, ie riding a 58×58 cycle when you would normally ride a 56×56 or a 54×54. Stand over height is sacrificed, but it is easier and more comfortable to sit on the top tube of a taller frame while waiting for a red light to change to green or for a friend who has stopped for a moment during a ride.

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Next up: Fitting yourself to a cycle and comfort on a cycle for rides of long duration.

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