Big Kev / Ride 415 Fork Offset Settings Explained

Big Kev / Ride 415 Fork Offset Settings Explained

You may have noticed the recent launch of our new Big Kev gravel-plus bike! One of the new features of Big Kev is that it comes equipped with the new Ride 415 fork. With the new fork, there are a few technical details regarding the ride characteristics that we'd like to explain so that you can tune your Ride 415 for your preferred ride feel when tackling various terrain.

In short:

The new Ride 415 fork is equipped with the ability to switch between two different fork offsets (also known as fork rake). It offers riders the ability to tune their bike's handling according to a desired riding style/preference or terrain. These two offsets will be labelled Forward (F) position and Backward (B) position throughout.

The F position makes handling quicker and needs less steering input to steer the wheel. Riding under load and at slower speeds will make the bike more controllable and is the preferred setup for most of the Curve crew when using Big Kev as a bikepacking bike. The F position is therefore the default position. Setting the offset to the B position slows down the steering and will be preferred by some as it will make the bike even more stable at speed. This is useful when riding unloaded around on faster gravel roads.


More in Depth:

F Position = 52 mm offset

The F position will give Big Kev a trail figure of 72 mm. No brake caliper adapter is necessary in this position.

Essentially: The shorter the trail figure, the quicker the steering. This will make slower speed riding (think technical single track) more controllable as less input is required from the rider to steer the wheel and point the bike to where you want to go. The opposite is experienced at fast speeds, where the quick steering will result in a more agile feeling bike as your steering input is exaggerated.

F position summary:
This setting would suit more of a bikepacking setup especially where Rocket Pooches, or some front load bags, are carried.

B Position = 46 mm offset

The B position gives Big Kev a trail figure of 79 mm. Please use the supplied brake caliper adapter when in this position.

In this application - The longer the trail figure, the slower the steering. The slower the steering, the more stable the bike feels at faster speeds. The byproduct of this stability at faster speeds is that at slow speeds steering becomes less stable. At slow speeds, wheel flop can also become noticeable, and some inexperienced riders may feel unnerved by this sensation. (Big Kev will not enter a dangerous range of wheel flop, but it is worth noting.)

The B position will also shorten the front centre figure (the distance from the centre of the BB to the centre of the front axle). This may increase the possibility of toe overlap in extreme circumstances. The geometry of Big Kev allows ample front centre space across all sizes and should, therefore, not enter a dangerous range meaning toe overlap should not be an issue. 

B position summary:
This setting would suit riders wanting more of a gravel race set up.

Note: Another way to increase or decrease your trail figure is to size up or size down your tyre size. The larger the front tyre you use, the more trail you will achieve. More on this later. 


What even is ‘Trail’?

The trail figure can actually be determined in two ways. Ground trail or mechanical trail. Ground trail is what most bike companies use and what we will dive deeper into here.

To obtain a ground trail figure you need two points.

  1. Draw a line from the centre of the axle vertically down to the ground. 
  2. Draw a line from the centre and at the angle of the headtube to the ground.

The horizontal distance along the ground between these two points is the ground trail figure.

The above diagram illustrates the ground trail figure based on what we specify as the optimal tyre size 29 x 2.1. This tyre has an outer diameter of 730 mm.

What Elements Make Up Trail Figures?

Head angle, tyre size and fork offset are the elements of a bike's geometry that make up this figure. Bike designers will find a balance of these three elements to obtain the desired handling characteristics according to the bike in question.

The general rules are:

• Steeper Head angle = Lower trail figure = Faster steering
• Smaller tyre = Lower trail figure = Faster steering
• Longer fork offset = Lower trail figure = Faster steering

Changing your tyre size is the easiest way to adjust the trail figure on most bikes. You may have noticed that your bike's handling may feel different after having tyres swapped. Particularly if swapping to different size tyres. 

The above diagram illustrates the ground trail figure based on a popular 700 x 45 gravel tyre. This tyre has an outer diameter of 715mm. As seen in Figure 1.0 and Figure 1.1, a difference of 3 mm is shown in the trail figure when changing nothing else apart from the tyres. This may seem like very little difference, but 3 mm is noticeable to the bikes handling. This along with the reduced weight of a smaller tyre will certainly be noticed.



Why is the trail figure so important?

One of the single most influential aspects of a bikes handling is the steering, and a bikes steering is dictated by the trail figure. The feedback of a bike’s steering is the first thing a rider will notice when riding a bike. So if this trail figure is not right, the bike will feel all ‘wrong!’

We take the handling of our bikes very seriously and we go to great lengths to ensure we have it right according to what type of riding the bike is likely to be subject to. This includes consideration to different tyre sizes and potential loads.

So there you have it! A whistle stop tour of the trail features of our new Ride 415 fork offset settings with a bit of jargon demystified for good measure. If you want to know more about Big Kev or the Ride 415 fork why not pop by HQ for a visit or get in contact with us for more information.

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    Hi James,
    Good question! And yes, that’s entirely correct. It’s not something I’ve specifically checked before, so I went ahead and crunched the numbers.

    All else being equal (apart from the flip chip orientation), you would have to go to a 700c x 35mm or 27.5″ × 2.1″ tyre to get the same trail figure. That’s a 40mm difference in wheel diameter which would, in turn, result in a lowering of the BB (and decreased ground clearance) of 20mm. The lean angle, i.e. the angle at which a pedal, with the crank at 6 O’clock, will strike the ground, is also reduced by 5˚ from ≈38˚ to ≈33˚. The exact angle very much also depends on the crank length and pedal used.


    Very informative layout of factors influencing trail. If the bike was optimized with the chip in F position and 2.1" tires, the B position should have a smaller tire size that has equal trail. Can you share that tire size with us, Curve?

    James Movius

    Thank you for the detailed explanation. I have the ride 415’s on my XXL Kev – built at Commuter Cycles (love the bike – I said I wouldn’t commute on it but now I ride it every day!).
    Neither Commuter Cycles or I can get the front brakes to seat properly – always resulting in scratchy and sketchy brake performance (GRX). I will have to look at the settings to make sure I am not in the B setting without the right spacer. Cheers

    Peter Corcoran

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