I'm too short!

How would you go about lowering a Commando?

Shorter shocks will look after the back of the bike but I'm hearing conflicting things about
what to do to lower the front.
Most say you need to shorten the fork tubes (or install shorter Atlas or Manx tubes) and
then cut a corresponding amount out of the spring, which makes sense. Where I get confused
is with what do do with the damper tube and rod. Based on what I know about how the forks
work shortening the fork tubes and springs will cause the bottom of the damper rod to sit
closer to the bottom of the damper tube, which means it will bottom out easily. So then it
would make sense to me to shorten the damper rod an appropriate amount as well. However,
according to the Clubman racing website both the Atlas and the Commando used the same length
damper rod! Adding to my confusion is the fact that Atlas damper tubes are 1 3/8" shorter
than Commando damper tubes.

What have others here done to lower their bikes?

Thanks!

Gary

Nithburg
Check with Matt at CNW. I believe they lower some of the builds.
Cheers,
Thomas
CNN

Lower the seat (usually remove foam)
18in wheels
shorter shocks
shorter forks

Commandos aren't the tallest bikes so that's the good news. There are a few people on the forum who have made these mods.

Might be the less expensive way .



might explain a few things . Platform boots were all the rage in the 70s . :lol: http://www.shoeoodles.com/mens-shoes-bo ... cycle-boot

How much do you need it lowered? If you could get away with thicker soled boots that would be better than altering the bike.
However, if the bike must be changed shorter fork springs and shorter rear shocks would probably be the quickest.

GB

How about less padding in the seat? A friend lowered his wife's saddle height a lot by cutting foam from the top and sides. Seems like a cheap fix. It worked for me when I went the other way with thicker harder foam. I like a tall bike.

You can follow my personal path in reducing the seat height of my Mk3 here:

mk3-rebuild-complete-for-now-t4121.html

While I went with a wider 18" rear wheel, I did this to gain a larger selection of tires (and cosmetics); my choice of tire had the same rolling diameter as the OEM 19" tire and thus had no effect in lowering the seat. Installing a shaved-down Corbin seat had a large effect, as did installing Atlas shocks. The shocks increase the rake by 0.75 degrees, in principle increasing the straight-ahead stability of the bike while reducing slightly the side-to-side quickness; truth be told, as a recreatonal rider I really can't tell the difference in handling.

For me, the confidence of being able to ground both boots at a stop was paramount in my rebuild. I remembered too many anxious moments when I had to stop quickly on my Combat and had to choose which boot to ground, the peril of a 34" seat height and a 29" inseam. I'm now free of these anxieties.

Mild pull-back bars address the short-arm problem.

On a stock bike the dampener rod length controls the stroke of the slider by having the valve crash into the inside of the dampener cap. So if you cut one inch off the fork tube (I do this a bit) and make no other changes you will find the sliders extending that one inch not really helping too much with lowering. So you would need to shorten the rod by one inch as well. I think you might find it better to use the light wt. Progressive springs with no 3/8 spacers and not shorten the stock springs it will make them too stiff. And also no more than an inch removed from tubes because of problems with the front fender crashing into things at full travel.

Not a cheap solution, but Norvil UK makes a 2" lower frame. See: http://www.norvilmotorcycle.co.uk/ part #065404LOW

Buy a Corbin seat..

There's an article on Norvil's website that explains how Les' daughter Kate had her forks lowered. I think her bike is a 650.
Hers was done by using shorter damper tubes.
The way I see it, this has exactly the same effect as shortening the spring and the damper rod.
Her bike also used shorter stanchions to reduce the risk of bottoming.

Because I also suffer from duck's disease, I lowered my forks by shortening the damper tubes. To be more precise, I cut the bottom section (the tapered piece) off the tubes and fitted new ones which I made. I lowered the ride height by 1/2".
My stanchions are standard so there is theoretically more chance of bottoming, but that has never been an issue for me. In any case, the Norton forks do have some degree of hydraulic bump stop.

However, topping out at full extension has always annoyed the hell out of me. Don't anyone dare tell me it's because of worn damper rods and caps, mine are fine, and that's in no way meant to provide a hydraulic stop anyway.
The workshop manual has an illustrated explanation of how the hydraulic stop at full extension is supposed to work. The only problem is that it can't possibly work with the components as they are manufactured; put simply, the two holes near the bottom of the stanchion are in the wrong position. Careful measurement of all the parts of my forks indicated that the holes should have been at least 43mm farther up stanchion. This has been known for many years and it would have been easy to correct when making replacement parts, but nothing seems to have been done about it.

The covenant conversion approaches the problem another way, by adding an extra (or a longer) top bush to overcome the fact that the holes are out of position.

The way I see it, my shortened damper tubes don't make the topping out situation any better or any worse. What they did mean however was that the extra top bush I added had to be longer than it otherwise would have been, by that extra 1/2".
It worked. No more banging forks.

Cheers
Martin

PS: Regarding your concern about the damper rod bottoming: it can't.
The stanchion will bottom out long before the rod gets anywhere near the bottom of the tube. Even with shorter stanchions the rod should stay well clear of the bottom of the tube.

Matt Spencer said:

Might be the less expensive way .

might explain a few things . Platform boots were all the rage in the 70s . :lol: http://www.shoeoodles.com/mens-shoes-bo ... cycle-boot

Click to expand...

These must be a lot of fun when you want to hook your instep under the gear lever to change gear :?:

Use these boots and convert to hand change :?:

Thanks for all the advice (and smart ass comments), its much appreciated. This weekend I had the opportunity to sit on another Commando that had been lowered about 2", and while it felt good to have both feet planted firmly on the ground I realized that I don't need to go that low. So I think I'm going to start off by trying a set of shorter rear shocks as Rick in Seattle did and see how that works, if its not enough I'll either shorten the forks or go shopping for some platform soles.

This is how my bike sits now:



Thanks

Gary

Shorter rear shocks is a good way to lower w/o much interfering with lean fouling sharpness but may have to modify side stand for resting lean angle. Its common practice to strap down a show room bike forks and rear suspension some so it shines better in the 1/4m testing, so might try that for sense of what length shock to fit. Just watch out for good size speed bumps to hi center on.

Gary,

Another way to lower the front is to purchase and install custom triple clamps which allow you to slide and clamp the fork tubes. Framecrafters makes a nice set for something over $600 with an eccentric to allow rake angle adjustment. Probably less costly items out there.

http://www.framecrafters.net

I am thinking that when faced with cost and time of cutting and machining of tubes and internals one would be well on their way to a simple bolt on item such as custom triple clamps.

You can also consider going with an 18 inch front rim which allows you to run some lower profile tires and gain some enhanced handling if you opt for an aluminum rim.

As mentioned above, reducing/changing the foam in the seat is another quick and simple way of reducing the seat height. There are service providers that do this and I can refer you to one in the Greater Chicago Area if interested.

You did not mention which Commando you wanted to lower so for reference, the 750 Commandos had a rake angle of 27 degrees whereas the 850 Commandos had a rake angle of 28 degrees (slower turning). Also note the raising or lowering the rear by 1 inch equates to decreasing or increasing the rake angle by roughly 1 degree.

Not suggesting you do any of the above but put them in your bag of tricks.

And finally, there's the Commando "hop-up" kit discussed extensively on other Brit Iron lists a few years ago.

Nithburg said:

Thanks for all the advice (and smart ass comments), its much appreciated. This weekend I had the opportunity to sit on another Commando that had been lowered about 2", and while it felt good to have both feet planted firmly on the ground I realized that I don't need to go that low. So I think I'm going to start off by trying a set of shorter rear shocks as Rick in Seattle did and see how that works, if its not enough I'll either shorten the forks or go shopping for some platform soles.

This is how my bike sits now:

Thanks

Gary

Click to expand...

At the front you may be able to get away with pushing the fork tubes up 1 inch though the top of the yolks, but check mudguard-frame clearance with front brake fully on

[/quote]At the front you may be able to get away with pushing the fork tubes up 1 inch though the top of the yolks, but check mudguard-frame clearance with front brake fully on[/quote]

you'd have to push very hard if it's a Norton? aren't all the top yokes tapered to match the top of the stanchions?

You can lower the forks sag by slicing out about an inch of factory spring, which stiffens it up and putting in a very weak thin spring just to take up the slack, then do the damper tube hole raising mod to give silent soft bottoming, which won't happen any more often than prior fork. Just use caution in the leaning at speed. Fitting 17" rim would lower some too, though 16" rear was once the rage and still is for a few most famous Commando riders.

Tyre Size AND rim size is relevant . a 4.00 18 is as tall as a 3.50 19 , at the risk of stateing the obvious .

You wanna check the Diameter or suchlike before committing to the expense . A W I D E low profile onell help stop the hardwear drag ing . Though the hated 16 in fronts were hated for bump steer , or the offset on the wobble bumping .
or was that the ofset on the bumps wobbling .



:!:

Matt Spencer said:

Tyre Size AND rim size is relevant . a 4.00 18 is as tall as a 3.50 19 , at the risk of stateing the obvious.

Click to expand...

Of course it is relevant if one insists on doing the same thing over and over again - what's that bit about insanity?

Just rough measured the OD of the 19" Commando with Dunlop K81's at 26"

By example, a Dunlop 2.75/3.75 - 18 will yield around a 23" OD. That would lower the front 1.5".