Rear wheel puzzle

BiKenG · Mar 18, 2018

I'm puzzled by the R1100GS Service Manual which states that to remove the wire spoke rear wheel, the caliper should be taken off first, but this is not required for the cast wheel. Why is that? I would have thought the Final Drive Unit was the same, with the disc attached to it, so why have to remove the caliper first? Or is the disc attached to the wire wheel?

Cyrano · Mar 18, 2018

Yes, on GSs and all 1150s the disc is attached to the wheel.

BiKenG · Mar 18, 2018

Thanks. Is there a reason for that do you know? Makes no sense to me as to why the different wheel construction would dictate a different brake disc attachment.

Does that apply to the last RHD 1200GSs also and mean that the Final Drive Units is therefore different for the different wheel types? I thought on bikes like the GS with cast or wire wheel options they could be swapped. Is this not the case? Could a wire wheel (without disc) be used on a Final Drive Unit with disc attached?

Steptoe · Mar 18, 2018

BiKenG said:
Thanks. Is there a reason for that do you know? Makes no sense to me as to why the different wheel construction would dictate a different brake disc attachment.

Com'on, give it some thought.

Wire wheel has a hub where you can mount the disc. A Cast wheel doesn't.

The wheel mounting flange on the final drive of 1100/1150 GS models has the same disc securing holes as used on the RT/RS models, but obviously it isn't used on the GS.

All the K series bikes have a final drive flange mounted disc.

BiKenG · Mar 18, 2018

Steptoe said:
Com'on, give it some thought.

Wire wheel has a hub where you can mount the disc. A Cast wheel doesn't.

Ha, thanks for the info, but I'd suggest you give it some more thought. There is NO reason why a cast wheel couldn't have the disc mounted. It has a hub just the same as a wire wheel, although it's all one piece of metal with spokes and rim.

However, that's not the real question. It is obviously (to me anyway) beneficial to have the disc staying with the Final Drive and NOT being attached to the wheel. This makes wheel removal and re-fitting a lot easier. So why did BMW NOT do that with wire wheels? Even if as you suggest they are ideally suited to have the disc mounted on them, why do that when it's a far better solution to have the disc mounted on the final drive?

In fact that rather begs the question of whether a wire wheel (without disc) can be fitted to a Final Drive that has the disc mounted on it? Is it in fact a choice as to where the disc is mounted? On the Final Drive or on the wheel?

jefformston · Mar 18, 2018

BiKenG said:
Ha, thanks for the info, but I'd suggest you give it some more thought. There is NO reason why a cast wheel couldn't have the disc mounted. It has a hub just the same as a wire wheel, although it's all one piece of metal with spokes and rim.

However, that's not the real question. It is obviously (to me anyway) beneficial to have the disc staying with the Final Drive and NOT being attached to the wheel. This makes wheel removal and re-fitting a lot easier. So why did BMW NOT do that with wire wheels? Even if as you suggest they are ideally suited to have the disc mounted on them, why do that when it's a far better solution to have the disc mounted on the final drive?

In fact that rather begs the question of whether a wire wheel (without disc) can be fitted to a Final Drive that has the disc mounted on it? Is it in fact a choice as to where the disc is mounted? On the Final Drive or on the wheel?

I'm sure BMW had a reason, not that it matters though simple fact it cast wheels weren't an option on the 1100/1150 GS models. It wasn't until the 1200GS came along that cast wheels made an appearance on the GS.

BiKenG · Mar 18, 2018

Ok, reasons aside, can a discless spoked wheel be fitted to its Final Drive Unit that has disc attached?

Paul Young · Mar 18, 2018

BiKenG said:
Ok, reasons aside, can a discless spoked wheel be fitted to its Final Drive Unit that has disc attached?

I don’t believe it can. The disc mounts on the spoked wheel hub would foul the arrangement.

Steptoe · Mar 19, 2018

Paul Young said:
I don’t believe it can. The disc mounts on the spoked wheel hub would foul the arrangement.

I did hint at that earlier but apparently it's wrong - but the fact that any combination can be fitted if you really wanted to do it that badly and at huge expense hadn't been considered. There are many K series bikes out there with the disc sandwiched between wheel and final drive flange with no disc mounting bolts just the four wheel studs going through the four wheel bolt holes in the disc, lost count in the past at the amount I've undone and disc had rolled away D

Steptoe · Mar 19, 2018

BiKenG said:
Ha, thanks for the info, but I'd suggest you give it some more thought. There is NO reason why a cast wheel couldn't have the disc mounted. It has a hub just the same as a wire wheel, although it's all one piece of metal with spokes and rim.

All wheels have hubs. But you were asking about Bmw wheels.

Paul Young · Mar 19, 2018

Steptoe said:
..any combination can be fitted if you really wanted to do it that badly and at huge expense hadn't been considered...

So true

. I've considered grinding the lugs off the R1100S rear wheel I'm using, so that I can go back to a separate mounting plate and not have to remove the caliper to take the wheel out.

Wrigsby1 · Mar 19, 2018

Paul Young said:
So true . I've considered grinding the lugs off the R1100S rear wheel I'm using, so that I can go back to a separate mounting plate and not have to remove the caliper to take the wheel out.

In the 10's of times I have changed tyres etc, using the toolkit provided, sometimes at th ed side of the road, it has never occurred to me why bm have wasted at least 3mins of my time each change... Also the rear rh pillion peg wold become redundant if I didn't hang the caliper there...

gog · Mar 19, 2018

Wrigsby1 said:
Also the rear rh pillion peg wold become redundant if I didn't hang the caliper there...

You mean that isn't what that sticky out part of the subframe was intended for? I always assumed it was called the 'caliper hanger'.

Steptoe · Mar 19, 2018

Wrigsby1 said:
In the 10's of times I have changed tyres etc, using the toolkit provided, sometimes at th ed side of the road, it has never occurred to me why bm have wasted at least 3mins of my time each change... Also the rear rh pillion peg wold become redundant if I didn't hang the caliper there...

I usually have to remove a rear wheel several times a week and it's never occurred to me what an inconvenience moving the caliper out of way could be.... A huge benefit is taking the opportunity to prevent the caliper from seizing on its sliding pins

BiKenG · Mar 20, 2018

Steptoe said:
I usually have to remove a rear wheel several times a week and it's never occurred to me what an inconvenience moving the caliper out of way could be.... A huge benefit is taking the opportunity to prevent the caliper from seizing on its sliding pins

Fortunately, you can keep on doing it that exact way and have to remove the caliper each time. I, however, see that as an irritating waste of time and effort if the disc can instead remain attached to the Final Drive Unit as per Honda SSSA arrangements with which I am more familiar and enables me to easily swap to different wheels and tyres while keeping the pads paired with the same disc. Otherwise you have to either swap the disc between the wheels or swap pads to keep them with their wheel and disc assembly, or you simply don't care and have to rely on the pads bedding in to the different disc each time.

We are all different with different requirements. Some riders can't be bothered to get off the bike while filling with fuel, whereas I prefer to stretch my legs while filling. No bother to me at all and I prefer to avoid any possibility of pouring petrol all over my trousers. But that's just me. We're allowed to be different and vive la différence I say. Well, I would if I was french.

Steptoe · Mar 20, 2018

BiKenG said:
We're allowed to be different and vive la différence I say. Well, I would if I was french.

And BMW is allowed to be different from Honda... vive la différence

Rear wheel puzzle

BiKenG

Registered user

Cyrano

Registered user

BiKenG

Registered user

Steptoe

What a waste.

BiKenG

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jefformston

Registered user

BiKenG

Registered user

Paul Young

Under-used member

Steptoe

What a waste.

Steptoe

What a waste.

Paul Young

Under-used member

Wrigsby1

Well-known member

gog

Well-known member

Steptoe

What a waste.

BiKenG

Registered user

Steptoe

What a waste.

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