Issue #009 Issue #010 Tours & Travel


What does a multi-day gravel adventure have in common with a bunch of Hi-Fi nerds, liquor-soaked fruit and a school trip? You’re about to find out. To celebrate the launch of its new gravel handlebars, the ACROS team invited us to take part in an exclusive adventure in the Swabian Jura – and five lucky GRAN FONDO-readers were chosen to tag along.

“Gravellers across the country, listen carefully and praise our new handlebars! You shall bring your gravel machines, strong legs and of course your best attitude!”

The solemn call spread throughout the country and reached the farthest corners of the realm. Of the many brave souls who responded to the appeal, unafraid of daunting new adventures, five lucky subjects were picked with a raffle. Shoulder to shoulder and dressed in their finest battle gear, the five “chosen ones” gathered in … Renningen — yes, Renningen, about 25 km west of Stuttgart. Once they arrived at the headquarters of German precision-components manufacturer ACROS our five heroes were easily recognizable — a huge grin on their face gave them away. “Finally we won something…”— you bet, and it’s way cooler than a stupid blender! Before jumping in the saddle we indulged in a rich breakfast and were given a comprehensive tour through the sacred rooms of the church of ACROS.

What does ACROS actually make? Many of us know the brand for its high-quality headsets but only a few of us know how much work actually goes into their production. For us and our five trusted GRAN FONDO readers the factory tour was a true eye-opening experience. As boring as the subject of ball bearings may sound to you this was a very exciting experience and a mind-boggling realisation of how much know-how and technology there is behind ACROS products. How much grease do you need to put into a headset? What distinguishes an average bearing from a good bearing? And why are Hi-Fi nerds so jealous of the ACROS test lab?

ACROS relies on a number of modern techniques and production processes which find their origins in space technology. Why? ACROS’ sister company Horst Weidner GmbH — WHG in short — is a premium German bearing specialist that offers custom solutions for high-tech products from heavy-duty cranes to satellites. Its maximum deviation tolerance sits in the micrometer range, which translates into 0.000001 m. These strict parameters also apply to all ACROS products.

Each bearing is specifically built for its intended use. This is why ACROS offers a vast range of different bearing-grease qualities to meet the requirements of the respective application. The most expensive grease costs over € 2,000 per kg!

But let’s answer our original question: an ACROS headset requires exactly 0.4 g of grease. ACROS buys its bearing-balls directly from Japan and the German bearing specialists claims to spare no expense or effort to meet its own, very high quality standards. We can only guess how much effort, love and work go into an ACROS bearing during production — our tour gave us a pretty clear idea and we gained some exciting insights. For example we know that temperature fluctuations can affect the accuracy of the milling machines to an extent that fine adjustments have to be made throughout the day. Demagnetizing machines also play a crucial role in this delicate production process; even the smallest magnetic load could prevent the parts from being washed properly and cause micro-sized metal chips to stick to the bearings. The devil is in the detail: when you weld a frame, the frame warps. At least with steel and aluminium you can easily re-align the frame once you’re done with the welding. ACROS bearings on the other hand only tolerate imperfections in the My range: 1 My is 0.001 mm. A helpful comparison? A hair measures between 0.08 and 0.1 mm of thickness. Last but not least is the acoustic quality control every ACROS bearing undergoes; this relies on instrumentation that would make any Hi-Fi nerd’s heart beat just a little faster. Each bearing is checked for noise – the lower the noise level is the smoother the bearing runs. The ultimate goal? Total silence!

A song made of headsets, liquor and gravel paths

But enough with the theory! Once the breakfast and the copious amounts of strong coffee had helped us wake up we started getting our bikes ready. Our destination? The Rohrauer hut in the Swabian Jura, more or less 80 km from Renningen. Sunshine? Check! Tyre pressure? Check! And off we went! Everyone in the group was looking forward to the gravel roads we had ahead of us. Erwin — ACROS’ Business Development Manager — hadn’t over-promised earlier that morning. The route took us along an old Panzer-route near Sindelfingen, past the local ammunition depot, through a strip of superb, freshly-laid tarmac and enchanted forest paths. It was hard to find the ideal tyre setup for this route and everyone had their very own opinion. If you’re after a comprehensive overview of the current hot gravel tire models available on the market you can check out our gravel-tyre test on.

With the sun at its Zenith we rolled into a lovely Swabian village. Everyone around here seemed busy working and getting the town ready for its annual Franco-German friendship celebration. We asked some of the local building crew: “Is there any beer yet?”. The festival hadn’t even started but we still managed to convince the locals to pull a few pints for us — after all, our gravel party was already in full swing. After a few kind words of persuasion we were finally holding a well-deserved, freshly tapped pint of cool beer in our hands. The moral of the story: there’s always a reason to celebrate and raise a glass!

The air felt hot as one of the last beautiful summer days was coming to an end — that’s exactly when we got to the foot of our last climb.

I spy with my little eye… and it’s red – that’s a hard one, it could be either the glowing fireball in the sky or the LEDs on my Wahoo announcing a galloping heart rate. Gravel climbs are still the best way to feel the burn in your legs.

From the edge of the cliff we dropped down into the valley — pretty much vertically as a breath-taking view gave us a last glimpse of sunshine — finally no more mountain was standing in between us and the last warm rays of sun — it was the Golden Hour. This called for a few more cool pictures and one last take with our flying colleague, the Mavic drone. But all of a sudden a clunky, frightening noise spoilt the peaceful silence “Bssst-clunk-phoooww… oh Shit!” and we we’re all looking in terror. Luckily the collision with the garden fence hadn’t damage our drone too heavily. We assumedthat our drone pilot was more focused on the village-celebration than on his actual job.

“Shush, the teacher is coming!

But luckily after this little incident with the drone, everything went smoothly on our way to the accommodation. Shortly after our arrival we realised that we were in for a surprise: a shared room! This made the school-atmosphere even stronger and after the second pint we were all pretty intrigued by the idea: “Psst the teacher is coming! To top off a perfect day there was a large bonfire with a barbecue, chilled beers and — you guessed it — liquor-marinated fruit. Of course, we wanted to find out whether the liquor was flammable but unfortunately a combination of slightly burnt bread sticks and schnapps-soaked fruit didn’t quite do the trick — none of us had managed to pass the fire breathing exam just yet…

The next morning the wild gravel-bunch set off to reach the ACROS headquarters. From here everyone would eventually return to the different corners of the country. The dream was slowly coming to an end. We cruised over forest highways and gravel paths, flew over smooth singletrack and old tank-routes and glided across freshly laid tarmac roads… to finally arrive to the Eselsmühle in the Siebenmühlen valley. We took a coffee break with the finest cakes and most beautiful vegan delicacies and got the last decisive motivational kick for the very last leg of our journey. We enjoyed a moment of peaceful rest under an old oak tree and realized: gravelling is just awesome. We’re feeling great. A good life can be this simple!

On the last meters Erwin took us by surprise and pulled a town sign sprint. Who says that gravel wheels aren’t suitable for road sprinting? Gravel miles make for many smiles: Arriving in Renningen there was a high-fiving mayhem, and a bunch of happy, very satisfied faces at the end of an incredibly successful weekend – with new mates, old friends and great experiences in our hearts.

Thanks a bunch ACROS!

This article is from GRAN FONDO issue #010

GRAN FONDO Cycling Magazine is published in a digital app format in both English and German. Download the app for iOS or Android to read all articles on your tablet or smartphone. 100% free!

Did you enjoy this article? If so, we would be stoked if you decide to support us with a monthly contribution. By becoming a supporter of GRAN FONDO, you will help secure a sustainable future for high-quality cycling journalism. Click here to learn more.

Words: Photos: Robin Schmitt, Axel Brunst