This is how it starts. I dial the arranged number, and a female voice tells me that our conference call is about to begin. Then, just as I realise I have no idea what Ralf Hütter's speaking voice is like, there he is: much younger-sounding than his 62 years, and, by the sound of it, a lot more relaxed about the interview ritual than I'd have thought.

"Hello, it's me," he says, enthusiastically. I then try a bit of night-school German. How are you? Wie geht's?

"Oh, you speak German."

A little, I tell him. Ein bisschen

"But you understand the lyrics in German?"

Some of them, I think, which really doesn't seem good enough, so I tell him that even if a lot of Kraftwerk's lyrics enter my head as sound rather than words, I definitely prefer listening to his group's music in its original language (take, for example, their 1981 UK No 1 The Model: in its English translation, rather clunky; in Hütter's mother tongue, both elegant and precise). There's then a quick exchange about the fact that he translates his own lyrics, before a pause.

"Have we talked before?"

No.

"How come you are into this type of music without meeting Kraftwerk?"

Well, here's the thing: you really don't do many interviews. At all.

At that, the last remaining original member of the most influential group besides the Beatles emits a sound I was not quite expecting to hear: the merest hint of a laugh.

In general, Hütter spares time for journalists about as frequently as Kraftwerk put out records. And look how infrequently they come: aside from the 2005 live recording Minimum-Maximum, Kraftwerk's last proper album was 2003's Tour de France Soundtracks. Before that they broke cover in 1991 to release The Mix, an anthology of souped-up treatments of some of their best songs, which represented the hard-won fruits of their conversion from analogue to digital.

This latter process, focused on their Düsseldorf studio-cum-HQ Kling Klang, seems to have taken around five years, which highlights Kraftwerk's somewhat mindboggling work cycles. Hütter talks about his operation in terms of a strong work ethic, and insists that he and his colleagues need to go into non-communicative seclusion to create their art; it is part of Kraftwerk's mythology that Kling Klang doesn't even have a phone. Less exacting minds might use all that time and calm to create no end of music, but that is not the Kraftwerk way, which seems to explain why three of the group's members - Wolfgang Flür, Karl Bartos, and, latterly, the group's co-founder, Florian Schneider - have now left Kling Klang for good. There are at least three reasons to suspect that Hütter and his three new(ish) Kraftwerk colleagues - Fritz Hilpert, Henning Schmitz and Stefan Pfaffe - may now be visible a bit more often. First, they have a brand-new live presentation, including a 3D segment (for which you'll need the obligatory glasses), about to receive its British premiere at the Manchester International festival. Second, this September should finally see the release of definitive versions of the eight albums - from 1974's Autobahn onwards - that form the Kraftwerk canon. On top of all that, Hütter assures me that new music will be on the way "soon", though this being a Kraftwerk interview, what that might mean remains unclear.

The prospect of interviewing Hütter only highlights his prolonged periods of public absence. It seems very odd that I know what he thinks about telephones, but aside from the prophetic hints contained in Kraftwerk's 1981 album Computer World, I have no idea what he makes of the ubiquity of text messaging and email. Mystery also surrounds the departure of Schneider, a subject rendered even more problematic by Hütter's famed reluctance to talk about either his personal life or his interior universe. His droll summary of his average day runs thus: "I wake up in the morning, I brush my teeth, I go to the studio, I work, I go back home, I eat, I sleep." All we know is that he lives close to Düsseldorf, taking time out to cycle thousands of kilometres every year, and apparently working diligently - but moving painstakingly slowly, while the world outside speeds on.

"We always work on new projects," he claims, before dispensing a beautifully Kraftwerkian take on what has often slowed them down. Essentially, they spent too long stuck in the dying days of the steam age, waiting for the right equipment to come along - particularly when it came to performance.

"I remember once, we played in Paris, starting around 8 o'clock or something," he says. "And all the big steel factories in the suburbs turned their electricity down, or up, and there was this big shock in the cable system, and the sequencers ran at double speed. We were so surprised." Another laugh. "The whole technical situation caused a lot of problems for us, so we couldn't play live. And all through the 80s, we didn't play at all."

This highlights one of Kraftwerk's interesting tensions: underneath the super-calm exterior, they have probably spent far too much of their career feeling terribly frustrated. This, Hütter reckons, is an essential matter of what he calls "psycho-electronics".

"It takes all kinds of different mental states, from patience, to anger, to a big smile when everything is functioning," he says. "But we chose to continue working, and follow the idea of the Man Machine. And for us, it's still working positively."

These days, their greatest allies are the laptops that carry the essentials of their show - which, he assures me, have worked just as well in freezing auditoriums in Tokyo as overheated festival tents in Australia. Technology, in short, has belatedly delivered: as Hütter coolly puts it, "The equipment is finally up to our standards."

Back in the distant past he issued one of his most fondly reproduced quotes, which once again seemed to cry out for a development that had not yet arrived. The telephone, he said, was "an antiquity - you never know who is calling, there is no image, it is an outmoded product that constantly disrupts work".

"Yes," he says now. "That was the 70s and 80s, [but] it still stands. You'd be polite, and pick up, and say 'Hello' and be surprised at what was at the other end of the line, maybe directing your future for the next minutes, hours, days. That's why in the studio we never have telephones. We choose to go into the music, creative process. Once this is finished, and we close the session, we come out again, and then, we've enough time to get in contact with our friends."

Has he been liberated by the advent of caller ID, or email, or SMS? Do those things make him more communicative?

"Yes, but it hasn't changed my general attitude. You know these situations: you're talking to somebody, and everybody's on different platforms all the time, so nobody's really concentrating."

What he says next is probably not intended as his verdict on Twitter - a Kraftwerkian development, if ever there was one - but it may as well be. "Everybody is becoming like ... " - he pauses - "a Stasi agent, constantly observing himself or his friends."

The concert in Manchester happens on 2 July. To Hütter's delight, it will take place in the city's Velodrome, also known as the National Cycling Centre - the mention of which takes us into a conversation about his most beloved pastime. Hütter, along with Schneider, took up cycling around the time of 1978's The Man Machine, and became such a fanatic that both Flur and Bartos blamed his obsession for Kraftwerk's dwindling productivity. At one point, he was said to be managing 200km a day; these days, he says, "a couple of thousand kilometres a year is possible".

And is he still in the habit of leaving the tour bus 100 or so miles outside the next city, and pedalling the rest of the way?

"Unfortunately not," he says. "We did that in the 80s: the bus would drop us, and we'd finish the last couple of hours by bike. But now, the tour schedule is so tight that mostly we're using planes. And when you don't know the territory and the habits of the traffic, or like in England on the other side of the road ... well, we have to concentrate on the concert." On a recent trip to New York, he says, he enjoyed cycling every day in Central Park, but avoided the roads. "It's not a competition with cars. I think that's a dangerous game."

In the early 80s, Hütter was injured in a cycling accident that happened on a dam on the Rhine. Cycling with his usual racing team, he apparently collided with another rider, and fractured his skull and went into a coma. Even temporarily, did it put him off?

"No. A lot of nonsense has been told about this, by people who were not even cycling with me."

It didn't affect the way he felt about cycling at all?

"No, and it didn't affect me. I got a new head, and I'm fine. It was a few days in hospital, and that's it. A very normal accident. It's one of those things where somebody tells a story, and the next guy adds another story, and in the end ... like I say, I got a new operation, and I got a new head. I just forgot my helmet, and I was in hospital for three or four days."

Is it true that having emerged from a coma, his first words were "Where's my bicycle?"

"Er ... no. I don't think so. But a lot of fantasy has been written."

Hütter does his best to benignly close such subjects down, a tendency that becomes even more pronounced when I ask him about the fate of Schneider, the member of Kraftwerk whose blankly kind face - seemingly always on the verge of a smile, without ever quite getting there - seemed to sum up their music's subtle emotional warmth to accidental perfection. It may not be one of the records that's about to be rereleased, but it is surely some token of his place in Kraftwerk history that their fourth album was titled Ralf und Florian.

Nevertheless, in January this year, just prior to Kraftwerk touring South America with Radiohead, it was announced that he too had left, after around 40 years at Hütter's side. News of his movements is hard to find: the most a few hours' research throws up is that he recently popped up at an electronic music convention in Frankfurt, looking as un-Kraftwerkish as could be imagined, wearing - of all things - a flat cap.

"He worked for many, many years on other projects: speech synthesis, and things like that," says Hütter. "He was not really involved in Kraftwerk for many, many years."

Do you miss him?

"Oh, what can you say? You have to ask him."

But do you feel his absence?

"No, not now. Because it's been such a long time, you tend to forget, because we're looking more forward. And it's been such a long time since he stopped working with us, so what can I say?"

Well, to take this down to brass tacks, are you in contact with him?

"No."

Needless to say, when the conversation returns to art and technology, he brightens up. For the record, Hütter does not own an iPod ("I compose music - I don't listen to much"), but when pushed, he sounds open to the possibilities that life beyond the CD is opening up. "What is an album? In that format, it was 40 minutes, by a decision made by vinyl: side A, and side B. And then the CD was longer - and now, it could be endless. We could do an endless album ... because for me, music is like 24 hours. We created the 168-hour week for Kraftwerk."

So in theory, there could be a 168-hour Kraftwerk record?

"Yes. Why not?"

This is how it finishes. A day after we speak, Hütter's PR forwards me an email. Peppered with Kraftwerk song titles, and written in the capitals-free argot that suggests a mind well acquainted with online communication, it reads a bit like a poem:

"hello john

further to our interesting conversation this afternoon

some thoughts about the continuum in the music of kraftwerk since the seventies

autobahn ... the endless journey ... the timing of the composition resulting from the technical possibilities of the vinyl longplaying record ...

europe endless .... and the final sequence ... endless endless

trans europe express .... sequencer rhythms playing themselves ...

and finally .... the robots .... and ...... music non stop ...."

His last words sound like a bit of a tease, but they will surely raise the spirits of those of us who would hate to see Kraftwerk tumble back into seclusion: ".... to be continued. ralf."

• Kraftwerk play the Manchester International festival on 2 July

mif.co.uk