Tuesday, 30 July 2013

How to Lower a CBR 1000F

CBR 1000F Lowering Link

There are various reasons why you might like to modify the stance of a bike.

Streetfighter types like to raise the rear ends of their bikes because they think it looks cool. The reason they think it looks cool is that vintage special builders do this to decrease the stability of their machines for more responsive cornering (with the added benefit of increased ground clearance, which means the bike can be leaned over more, which also helps with cornering). And it does look cool (up to a point).

Drag racer types lower both ends of their bikes for arcane reasons to do with centres of gravity and moments of inertia. Basically, it makes the bikes less inclined to wheelie.

Off-road types like to raise both both ends of their bikes for better ground clearance over obstacles. 

Adventure bike types also do this even though they don't generally need better clearance over obstacles. What they really need is to get their feet down securely to stabilise their heavy machines so lowering them might actually be a better way to go.

Which brings us to road-riders, who generally only lower their machines in order to better touch the ground with their feet.

I've been talking about lowering Big Honda for a while now and there are a number of reasons why I wanted to do this.

Firstly - Cosmetics. I like long, low bikes. If you have a bike that's already quite long, and you lower it, it looks even longer. I love that stretched street-bike look. I suspect it might be a bit dysfunctional, but as a look, it rocks! And at some point in the future, I may take Big Honda this far, but for the moment I just want it to be a little lower, and look a little longer without compromising it's useability too much.


How to Lower a CBR 1000F
As a practical daily runabout this may be slightly compromised but I think it looks fantastic!
Secondly - Feeling. I've run a number of lowered bikes over the years and I like the way they feel. Lowering the centre of gravity just feels more stable and secure and controlling the bike feels easier. But there's a tradeoff - you can't lean as far before bits of the bike start touching the ground. This is obviously detrimental to handling. However, driving normally, on a public road I very seldom lean a bike so far that it touches down, so on a road bike, and particularly on a tourer, I'm happy to trade some of that unused lean angle for the feeling of solidity.


How to Lower a CBR 1000F
Big Honda's new stance.

Thirdly (and this is really the main reason) - Comfort. It's comforting to be able to get both feet flat on the ground and it's nice to be able to get on and off a bike without any effort (Fully loaded adventure bike, I'm looking at you) but that's not exactly what I mean.

You see, the CBR 1000F has clip-on handlebars and they're quite low. If you want to go fast (over 90mph) it's a pretty comfortable bike. But when you're not going fast, (which if you live in a city is most of the time) you carry too much weight on your wrists and the bars stretch your shoulders and neck. 



How to Lower a CBR 1000F
VFR Clip-on bars mounted at the very top of the fork stanchions. The yokes (triple-trees) have been dropped down the forks, lowering the front of the bike while the rear of the bike has been dropped using a lowering link. This effectively raises the bars.

So my first attempt to alleviate this discomfort was to fit clip-on bars off a 1989 VFR 750. These pretty much bolted up with no modification. They're about 2" higher and a little closer so they do give an improvement. But on the trip to Kerry I still had pains in my neck and shoulder (from an old injury).

When I first put the VFR clip-ons on, I fitted them so that they were flush with the top of the fork-leg as opposed to touching the top of the top-yoke (triple-tree). This raised them about another 10mm. So, my really convoluted  reason for lowering the bike, was to bring the fork legs higher up in the top yoke which would effectively raise the bars.

In fact, the bars stay exactly the same height they've always been, but the rest of the bike is lowered under them. 


How to Lower a CBR 1000F
The new office. Note the GPS holder mounted on the filler cap bezel. More details on this Here


I could have just fitted handlebars which would have taken about the same amount of effort, but like I say, I just like low bikes. In fact, if I still get pains in my neck and shoulder, fitting handlebars will be my next move.

So how do you go about lowering a bike? 

Well the front is easy, you just open the yokes and slide the forks up through them, then clamp the yokes up again. I'm oversimplifying this a little, but not too much. You need to have an idea of how much travel the forks have so the fork-sliders/mudguard/wheel don't hit the bottom of the yoke. And if your bike has handlebars (as opposed to clip-ons) you might only be able to lower the bike a little before the fork legs hit the bars. With clip-ons this isn't an issue. It's generally possible to lower the front up to about two inches using this method. 


How to Lower a CBR 1000F
After lowering the rear, sliding the forks up inside the yokes restores the rake angle to it's normal setting of 27 degrees off the vertical.


How you lower the back depends on what kind of rear suspension you're dealing with. With a twin-shock setup you generally just fit shorter shocks, but you could relocate the shock mounts if you're a bit more adventurous.

This works with a Cantilever Monoshock  too, but you might be lucky enough to have a shock that's adjustable for ride height. The Öhlins shock on my Superlight has a couple of inches of ride height adjustment.

All this stuff works on a Rising-Rate Monoshock too, but cutting and welding the shock mounts is a lot of effort - there are much easier ways. Replacing the shock for an adjustable (or shorter) one is relatively easy but quite expensive unless you're lucky enough to pick one up second hand. The generally accepted way to lower this type of suspension is to use an aftermarket lowering link.

These are easy to get for popular, late model bikes and are easy to fit. 

My last couple of posts Here and Here deal with this in a bit more detail, but essentially, I wasn't able to get a lowering link for a CBR 1000F so I made my own. This dropped the back end by 30mm.

I then lowered the front by a corresponding amount by sliding the forks through the yokes as described above.

So now the whole thing sits a bit lower, except the handlebars, which are where they always were but feel like they've been raised.  The geometry remains essentially unchanged and the suspension works the way it's always done (in other words, it's no worse, but there's still room for improvement). I've ridden it for a couple of days (including some off road trails on Sunday) and ground clearance isn't an issue. It'll still do kerbs and speed bumps without touching down. So from a useability point of view the bike is unchanged.

However, the bike looks cooler without looking like it's really low.

It feels nicer to ride - it's hard to describe, but Diane drove it and she said it felt better too.

And it's more comfortable - the extra 30mm height on the bars puts them pretty much where I want them to be. I'll be going for a long trip next weekend so it remains to be seen if they're comfortable enough...



How to Lower a CBR 1000F
Does this make my boom look big?


#BigHonda #CBR1000F #CBR1000FTouring #Mercenary #MercenaryGarage

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