Researched and written by IanJ July, 2006
Why a different shock?
One of the deficits of the Ninja 250 is that its stock rear shock is severely undersprung for a heavier rider such as myself. When I bought my new '06, I knew that I would want a better shock, and ended up gathering a good amount of information on what is available. This is an overview of that information.
If you're overwhelmed by terminology, there's a brief glossary at the end of the article.
There are two broad classes of shock available for the Ninja 250: those from other bikes, and those produced specifically for the 250 by the aftermarket. This article focuses on aftermarket shocks built specifically for the Ninja 250.
The aftermarket options
There may be more than these options available, but this is what I've found so far.
The Bitubo XZE01 will theoretically fit the Ninja 250. Bitubo has a decent reputation as a maker of suspension components, their products gracing a number of Italian bikes. Their published information is sparse, but we may reasonably conclude that their shocks use a shim-stack valve and an internal reservoir. Adjustments include preload and rebound, but not compression.
The US distributor gave me an impression of extreme cluelessness on the phone, and I would tend to avoid Bitubo for that reason alone. He said the current price on an XZE01 is $571, although that fluctuates due to the exchange rate between the US dollar and the Euro.
This shock would probably be suitable for any type of riding, from commuting to racing. It's likely to be comparable to the Penske or Hagon shocks, probably falling somewhere between the two in terms of performance.
Dave Quinn is the US distributor for Hagon shocks, and although it's not specifically listed on his website, the Hagon website lists a fitment for the Ninja 250 (search for GPX250R/EX250F). The part number is M64007, and the October, 2007 price is $394. If you need an uprated spring (and at 240 lbs in gear, he said I didn't need an uprated spring), there's an additional $60 fee for the larger spring and valving adjustments.
Hagons use shim-stack valves, and are emulsion (non-reservoir) shocks. They're adjustable for preload, and have a combined adjustment for rebound and compression. The combined adjustment uses a balancing valve system, so all you really have to do is dial in more or less damping, and the shock takes care of the balance between rebound and compression damping.
Due to the emulsion system and the linked compression and rebound damping, this shock is suitable for commuting through track-day use, but is probably a bit sub-standard for racing. In particular, the emulsion nature of the shock means that hard use will see it cavitating and losing damping, and the linked adjustment may not provide precise enough control for more advanced racers. Here's a comparison of the Hagon and the stock EX250 shock.
Ohlins is a well-oiled marketing machine. Their suspension components are good, but they're not generally worth the 30% premium over other good suspension components. That's particularly true on the Ninja 250, where the rest of the bike can't match the shock's capabilities. Avoid Ohlins shocks for the Ninja 250 unless you truly have more money than sense.
Ohlins shocks start at around $1100, and go up from there.
Penske is in a similar boat with Ohlins. Like Ohlins, their products exceed the Ninja 250's performance, particularly as regards frame and fork stiffness. Unlike Ohlins, the consensus of opinion is that their components are worth the price.
With that said, the Penske 8900 series (and any other models which fit) would make an excellent upgrade to the Ninja 250, particularly for top-tier racing. Penske uses current shim-stack valve technology, and even their most basic shock (Penske Sport) includes preload, rebound, and ride-height adjustment. It can also be upgraded to a full race shock at any time.
For racing use, spring the extra $200 for the $800-level fully adjustable shock.
The other reason to consider a Penske is that Penske shocks are modular, and can be easily and relatively cheaply reconfigured for another bike. So, if you're planning on upgrading to a different bike, it might make a lot of sense to upgrade to a Penske shock now, and take it with you when you swap bikes.
An aside from BrianM: "The Penske Sport is only a viable option for someone who wants the full Penske shock, but can't afford the $800 up front. So you buy the Sport now, and then when you get the money together you send the shock back with another $300 and have it converted to an 8981, or $600 and get an 8987 (87 is the triple adjustable, not worth it for anyone shy of a racer)."
"I can't recommend the Penske Sport without the future upgrade. It's just WAY too expensive for the limited function it returns. Even with the full 8981 iteration, it's pretty expensive for most 250 owners/riders. One of those things to lust after, but not really within the scope of the majority."
Works has been making shocks for motorcycles since 1973. Unfortunately, they have stuck with that 1973-era technology, and are still using it in all their products. That is, they're using the now-outdated ball-check valve. This makes them harder to adjust and harder to rebuild.
Along with the 1973 tech, however, comes a 1973 price. The basic Works shock (the Steel Tracker) can be had for $350, $420, or $500. The $350 version includes preload adjustment only. The $420 model has preload and rebound adjustment. The $500 model incorporates all three adjustments: rebound, compression and preload.
Aftershocks Suspension says they've set up numerous Ninja 250 racers with Works shocks with good success. Aftershocks' president, Phil Douglas, explained that the Works shocks are a good match to the 250's level of performance, particularly for the price point. He explained that he rode a Ninja 250 as both a racer and a street rider for a number of years, which is how he came to his conclusions about suspension components for the bike.
WP (not to be confused with Works Performance -- WP used to be called White Power, but you can imagine why they changed their name) makes excellent shocks. They don't make a model specifically for the Ninja 250, but they list the EX500 as a supported model. Any shock which fits the EX500 will physically fit the EX250, and will be sprung and valved pretty close to correctly.
There is no US distributor, so the price is only a guess. The WP website had me call the US KTM distributor, who said I should call my local dealership. After calling 7 different dealerships, I haven't found one which can even order WP parts. WP doesn't seem to be making a huge effort to sell aftermarket products in the US; there isn't any information on their distributor list.
The EX500 shock model number is 17.17.H9.03 according to their fitment list (an Excel spreadsheet file). Click on Which for my bike.
The WP shock most likely uses shim-stack valves. Their website says they offer adjustable length standard (which will allow you to raise or lower the rear of the bike), and that the listed shock comes with preload and rebound adjustments. This shock will be suitable for all types of riding, from commuting through racing.
Suspension companies with no EX250 shock
The following companies produce suspension components, but don't have a model which fits the Ninja 250 (not an exhaustive list):
Ball-check valve: one of two common methods used to achieve damping in a shock. A ball-check valve is usually implemented as a steel ball pressed into an orifice by a spring. Oil is forced past the ball to achieve damping. See also shim-stack valve and damping.
Compression damping: a reduction in the shock's ability to compress freely. Compression damping enhances rideability on the leading edge of a bump. See also damping.
Damping: a reduction in the ability of a shock to move freely. This is typically done by forcing oil through some kind of a restriction. A spring without a shock absorber has no damping whatsoever.
Emulsion-type shock: a shock which provides no barrier between the oil and gas (usually air or nitrogen) in the shock body. Emulsion shocks are typically not pressurized. Because of these two factors, the air and oil can mix (either via churning or cavitation), which reduces damping effectiveness. Contrast with the reservoir-type shock.
The oil and gas mixture will separate after a short period of sitting, and these types of shocks are fine for the street. They just won't hold up under the constant stress of racing.
Preload: the amount a spring is pre-compressed by the suspension system. Spring preload compresses the spring by a set amount (this amount is usually adjustable, although the stock Ninja 250 shock lacks this adjustment), which corresponds to a certain amount of weight, as determined by the spring rate. See also spring rate.
Progressive spring: a spring which has been wound such that the spring rate is non-linear. Usually a progressive spring will start out very soft, and get stronger as it's further compressed. Most suspension professionals do not recommend progressive springs because they complicate suspension tuning, and can actually make suspension less responsive. See also: spring rate. See also: Why Progressive springs are a bad idea
Rebound damping: a reduction in the shock's ability to expand after being compressed. This is a shock's main job. Rebound damping keeps your bike from bouncing up and down like a pogo stick. Adjustable rebound damping is usually desirable, and is more important to have than a compression damping adjustment. See also damping.
Reservoir-type shocks: shocks which provide some kind of barrier, usually either a flexible rubber barrier or a metal piston, between the oil and gas (usually nitrogen) in a shock. Reservoir shocks are usually pressurized. Because of this pressure, the oil can't cavitate under heavy use, making them better suited to high-stress environments such as racing or offroad use. Contrast with the emulsion-type shock.
Shim-stack valve: one of two common methods used to achieve damping in a shock. A shim-stack valve is much what it sounds like: a stack of thin pieces of metal, precisely shaped and sized. It is held together by spring pressure, and oil is forced through it to achieve damping. Shim-stack valves are a more modern design than ball-check valves. Their primary advantages are greater flexibility in tuning, and easier tuning. Contrast with the ball-check valve.
Spring rate: the amount a given spring compresses for a given weight. Front fork springs are usually expressed in kilograms per millimeter. Rear shock springs are usually expressed in pounds per inch or kilograms per centimeter. For instance, a 450 lb/in spring will compress one inch when 450 lbs is applied to it, or two inches when 900 lbs is applied to it. Spring rates are usually linear unless they're explicitly stated to be progressive. See also progressive spring.