Low/Standard Suspension

[ChazzyB]

Me neither, just trying to be friendly and helpful. It’s not a challenge, I couldn’t care less either way.
Sent from my iPhone using Tapatalk

I have some old fork springs in my garage. Several sets in fact. In reverse order of age: An SV650, a T140 and a 1953 AJS (fork and shock). I bet you a shit load of money that if I take any one of those springs, stick a kilogram weight on the top and measure the compression, then cut the spring in half with my metal-cutting disk and repeat the test, that the compression afterwards will be less.

No, forget the T140 springs - they were progressive wounds which I replaced with linear which were much better.

 

[ChazzyB]

why throw money away if you don't have to?.. a 2014 GS TE with 10k miles and a load of options fitted for £7500?.... maybe its worth a look.. sorry if it causes you grief...

No problem for me. I have a lowered GS already. ;-)

 

[beaver]

No problem for me. I have a lowered GS already. ;-)

what size are you?... leg measurement?

Is it a good deal... most are at least £1500 more with a lot higher miles.....

 

[ChazzyB]

what size are you?... leg measurement?

I hesitate to divulge that in a public forum. But it's short. 28" or 29" inches depending on how much I've had the night before... It's my second factory-fresh lowered GS.

 

[beaver]

I hesitate to divulge that in a public forum. But it's short. 28" or 29" inches depending on how much I've had the night before... It's my second factory-fresh lowered GS.

so at 6' and 32" leg, do you think a lowered one would be too low for me??

 

[ChazzyB]

so at 6' and 32" leg, do you think a lowered one would be too low for me??

Why would you, being of somewhat larger stature?

OTOH, if you put a normal height seat on the lowered GS the seat to footpeg distance is the same, just a bike that sits lower to the road. The standard low seat can be raised. Arguably, the lowered bikes handle better. Must be the shorter springs... ;-)

 

[beaver]

On the road, to get the weight lower is always good... thats what I'm thinking.. lower bike, higher seat?

not sure what bike size they recommend against person size?

 

[ChazzyB]

On the road, to get the weight lower is always good... thats what I'm thinking.. lower bike, higher seat?

not sure what bike size they recommend against person size?

Buggered if I know. I just want to be able to get on and off a bike without too much trouble and not fall over when I stop. My lowered GS does that for me. I can't flat foot anywhere, so I'm careful when I need to stop. But on the move (as soon as), I love it.

 

[Sea Dog]

so at 6' and 32" leg, do you think a lowered one would be too low for me??

I'm getting on for 3 or 4 inches shorter than you and I manage a standard suspension bike with the standard seat in the low position perfectly happily. There's a much bigger market to choose from at original height, and a much bigger market to sell it back into. The lowered bike definitely has a place for those who simply aren't tall enough to manage a full size GS, but I can't see how you fit into that bracket - and neither does the BMW online seat configurator. Have you properly test ridden one?

 

[beaver]

But the 'low' bike is only 20mm lower than a normal one... thats 3/4"..... so nothing really?

 

[fred_jb]

so at 6' and 32" leg, do you think a lowered one would be too low for me??

It's not going to be too low, since the seat to footpeg distance will be no different to the standard bike with a low seat, and you can swap the low seat the lowered bikes come with for a standard seat, which is what I did. I'm just over 6' but have only average legs (31) and a long torso, so I ride the lowered bike with standard seat. I usually have the seat in the high position for solo use but put it in the low position with a pillion to get an even more secure footing. So same comfort as standard bike, lower centre of gravity, more secure footing - what's not to like?

 

[Mr Bean]

I have some old fork springs in my garage. Several sets in fact. In reverse order of age: An SV650, a T140 and a 1953 AJS (fork and shock). I bet you a shit load of money that if I take any one of those springs, stick a kilogram weight on the top and measure the compression, then cut the spring in half with my metal-cutting disk and repeat the test, that the compression afterwards will be less.

Not if it has been linear wound it won't, the compression will be the same. If progressively wound it might, or might not depending on which part is cut.

 

[ChazzyB]

https://www.quora.com/If-a-spring-is-cut-in-half-what-happens-to-its-spring-constant

 

[beaver]

It's not going to be too low, since the seat to footpeg distance will be no different to the standard bike with a low seat, and you can swap the low seat the lowered bikes come with for a standard seat, which is what I did. I'm just over 6' but have only average legs (31) and a long torso, so I ride the lowered bike with standard seat. I usually have the seat in the high position for solo use but put it in the low position with a pillion to get an even more secure footing. So same comfort as standard bike, lower centre of gravity, more secure footing - what's not to like?

Hi.. thanks for that.. I'd kind of thought last night not to bother with it... but you posting this at 6' may of changed my mind a bit... you can even get high seats...
I know the actual bike is the same.. just how close it is to the floor changes...
Does anyone know the actual reduction in height of the bike... say filler cap as seat height is very confusing... I know you quoted 20mm before, but have seen up to 2" quoted as the actual reduction??

 

[fred_jb]

Hi.. thanks for that.. I'd kind of thought last night not to bother with it... but you posting this at 6' may of changed my mind a bit... you can even get high seats...
I know the actual bike is the same.. just how close it is to the floor changes...
Does anyone know the actual reduction in height of the bike... say filler cap as seat height is very confusing... I know you quoted 20mm before, but have seen up to 2" quoted as the actual reduction??

Because they automatically supply the lowered bike with low seat they tend to quote the overall reduction in seat height compared with standard suspension/standard seat. However, I'm sure that the ride height of the bike is only reduced by 20 mm, and assuming the normal sag of the bike when loaded with rider is about 1/3 of the suspension travel, then the difference reduces to only about 14 mm when (equally) loaded, but as they say - every little helps!

 

[fred_jb]

I have some old fork springs in my garage. Several sets in fact. In reverse order of age: An SV650, a T140 and a 1953 AJS (fork and shock). I bet you a shit load of money that if I take any one of those springs, stick a kilogram weight on the top and measure the compression, then cut the spring in half with my metal-cutting disk and repeat the test, that the compression afterwards will be less.

No, forget the T140 springs - they were progressive wounds which I replaced with linear which were much better.

The two half springs have the same rate (how many mm they deflect per kg of load) because the rate depends only on factors such as the stiffness of the material, diameter of the wire, etc, and not on the overall length.

What you may be confusing this with is the total amount of compression and therefore suspension travel available from the spring - this will depend on the length, so will be half for the half spring.

EDIT: not sure about this now - will do some more research!

I take it back - spring rate also depends on number of coils so you are correct to say that all things being equal the half length spring will be stiffer.

See: http://www.bluecoilspring.com/rate.htm

Fred

 

[fred_jb]

https://www.quora.com/If-a-spring-is-cut-in-half-what-happens-to-its-spring-constant

Haha - love it!

 

[beaver]

Because they automatically supply the lowered bike with low seat they tend to quote the overall reduction in seat height compared with standard suspension/standard seat. However, I'm sure that the ride height of the bike is only reduced by 20 mm, and assuming the normal sag of the bike when loaded with rider is about 1/3 of the suspension travel, then the difference reduces to only about 14 mm when (equally) loaded, but as they say - every little helps!

People talk about scraping things and their boots around bends etc... this I'd guess to be more than 20mm... just talking to a dealer in Preston... he's saying you can't increase the height on lowered ones.. and a lower one scrapes!.. makes you wonder how they get away with selling the things!

 

[beaver]

Here we go.. definative answer from people who know (its sad ite not BMW.. they we're clueless!!)

The K50/K51 GS stanchions have been superceded four times, culminating in the current part number 8404842. This is because of issues with the aluminium top plugs not being crimped into the stanchions tightly enough.
All supercessions are interchangeable, i.e. all variants are the same length. So, yes, that is bull.

The ESA level sensors (6870000, identical front and rear) will indeed need to be recalibrated when fitting the replacement shocks. You can either do this at the dealer’s using their in-house diagnostic computer, or do it yourself by purchasing either the GS-911wifi or GS-911usb Generation 2 diagnostic tool. Here is a link to the manufacturer’s site;

https://www.hexcode.co.za/

The rear level sensor attaches near the upper left rear subframe mount, with a rod down to the rear swing arm, and the front one attaches to the front left of the main frame and has a rod down to the left hand side of the Telelever arm – obscured behind the left hand radiator. You shouldn’t need to touch the sensors, however.

Regards,
Stuart

www.motorworks.co.uk

 

[fred_jb]

Interesting information, but I would expect the stanchions to be no different between lowered and standard bikes, as it is the spring/damper unit which is shorter on the lowered bike.