Telelever Front End

Hi pittsy, thanks for that, in fact one of the toughest things about MCN's TechWatch is keeping the articles down to that size, there's always lots more I'd like to expand on. But it's aimed at a fairly broad readership, some who are very interested and now a lot already, and others who have only a general interest, so they need to be short and punchy if possible. What I tend to do therefore is split subjects up and write about different aspects of the same thing - I've covered other aspects of Telelever before, including its suitability for ABS and the additional unsprung weight compared with forks, as well as that harsh ride.

You could make the wheelbase change very little by altering the geometry, but that would affect how much it dives under braking too, and I think this would become excessive if you did that (either that or it would rise up like a Honda Cub when you brake, I haven't looked at the detail of geometry changes). What's important is that the force pushing the wheel horizontally back towards the bike is acting to extend the suspension by an amount that balances the weight transfer attempting to compress it. As the geometry is now this force is slightly less, so you get a little dive, but change the geometry and you change this too. So as always there's a compromise being struck here.

Herb, there's a fascinating article on the problems of the Desmosedici here:
Desmosedici troubles

Interesting read that Kevin.

I think the whole MotoGP fanbase is watching Ducati with interest to see what they do.

I was speaking with an Italian colleague and he said public opinion is with Rossi. Ducati are expected to get Rossi to the front and if they don't their reputation in Italy will take a very long time to recover.

Sorry to hijack the thread.

I'll have a nibble...

When BMW first introduced Telelever on the R1100RS way back in 1993, with a little pushing they admitted the unsprung mass was - and this is from memory - 1.8kg (4lb) more than the equivalent telescopic front end - conveniently there was a K-series which used the same wheel and brakes, and the 1100RS set-up was 1.8kg more than that. This has been reduced as Telelever has been developed, but two years ago when I was discussing this with some BMW engineers we were still chatting on the assumption that telescopic forks have the smallest unsprung mass.

In fact they refer more accurately to unsprung inertia, which takes into account what you're saying about the A-frame's base moving less rapidly than the point end, but even then they say telescopic forks are superior in this respect. Where performance really matters, even BMW use telescopics, as with the S1000RR.

The proportion of unsprung to sprung mass does matter, a very heavy bike will have a better ride quality than a light one with the same unsprung mass, certainly, as the forces being transmitted up through the suspension will be same yet they'll be working against a greater mass, which in turn will accelerate (vertically) more slowly.

But there is an absolute here too, that unsprung mass should be as low as possible, regardless of the sprung mass. First, it takes more effort to force a heavy wheel up over a bump than a lighter one. That extra effort is transmitted through the tyre, so this is worked harder by increased unsprung mass. When the wheel reaches the top of the bump, with increased mass its inertia is greater, therefore it has a stronger tendency to lift clear of the top of the bump rather than stay in contact with it. In other words, reducing unsprung mass means the wheels and tyres are more capable of following the undulations of the road surface, so grip is improved and the tyre is worked less hard.

Agreed, if the sprung mass of the bike is greater the springs are stronger and the force holding the wheel to the ground is greater is it moves up and down - hence ride quality is better - but you still gain by reducing unsprung mass as it will do all of this better still when the weight is lower.

The mass is very relevant then of the unsprung components because they are constantly being accelerated vertically over bumps in the road, and with force = mass x acceleration. The forces generated by bumps at a given speed are the same, so the acceleration of the wheel (and again I mean vertically) increases, meaning it's able to follow the surface of the road more accurately.

Only one simple formula there...

Pittsy, the HP2 Sport engenders the same avaricious thoughts in me.

I agree that the detailing on the bike is superb, but two things put me off. The first is that replacement panels are on the expensive side, with something like the belly pan being several thousand pounds. The second is that the engine needs a full rebuild at the 25,000 mile mark.

I'm still tempted...

I found this site quite interesting so I bookmarked it for future reference.

http://www.carbibles.com/suspension_bible_bikes.html

I have never ridden a Duolever bike, but I like the feel of the Telelever on my R1200s.

Turn in is excellent, and if necessary (ie I have messed up) I can hold a line while trail braking towards the apex, the bike continues to hold much the same line when the brakes are released. There is still a slight tendancy to run wide, but no where near as much as on my previous bikes with conventional suspension, and its easily correctable with minimal steering input.

BMW have stuck with funny front ends for a long time. Someone must believe in it, hopefully for more than just marketing reasons.

If they do I have never noticed. I will have to check that out next time I ride it.

Do your bars rock? I dont see why the 'S' would be any different to the 'R' in that respect.

I've owned a number of telelever (boxers) and duo-lever (K's) bikes. Separating the suspension from the steering, like a rear wheel drive car is a good thing in theory in terms of allowing each item to get on with it's job respectively.

The telelever takes time to learn. It does have feedback, but its far more subtle than conventional USD forks. It takes time to fully appreciate and gel with it's feel and the feedback that it offers. Once fully acclimatised, you can place your trust in it and bully it into race-rep type heavy counter-steering forces as you thrust it hard from one side to the other again.

By contrast, duo-lever feels a heavier piece of engineering, but does seem to offer a little more in terms of conventional feel and feedback.. I think turn in rate, or at least effort is heavier/slower than the telelever, but the overall design looks more robust and feels more conventional for those who fear change/difference.

The thing that I most like about both systems and in particular the tele-lever is a significant reduction in rebound stroke, as felt through the wrists. Having broken both wrist twice and them being tenuously held together with a titanium trellis frame (bologna red natch) in each, I really appreciated how much I didn't have to back off when hitting rippled tarmac and pot-holes on modern Beemers.

In addition, without such significant fork dive, it gave my wrist a far easier time when braking really hard. This doesn't work so well with a sports bike because you need to load up and push the front tyre much harder. But with a relatively skinny Adventure bike tyre it's ample often advantageous.

To put what I have written above into context, the last time I rode a boxer I didn't enjoy it all that much, for the simple reason I'd been off them too long. They're not a CBR, that when you jump on, it feels like you've never been away from it. However, once fully dialed in again. I.e. Living with it, rather than just demo riding it, like a Harley in a different vein - it just kind of gets under your skin and you get attuned and in tune with it's feel, and the same with it's engines character. Then what happens is if you haven't ridden a mainstream bike in a long time, you try one and then can't wait to get back to your boxer again.

That's the hook and that' s why most owners who move on from BMW's and try other things, often end up returning to the marque, no matter which bike range they try with BMW the next time around. And, for instance, BMW sales are up hugely in America and yet surprisingly their top seller isn't the GS, but the conventionally suspended S1000R!

Pittsy. The telelever has two pivot points moving independently to the front wheel so that probably has an impact.......what I can't fathom.