10 May 2010

bikefix Exclusive: DIY Thru Axle

When I posted the build sheet for my Maverick ML8,an anonymous commenter asked why I hadn't gone with the 20mm thru-axle version of RockShox's Revelation on the big-travel fork. There were a number of reasons for my decision, including the shortage of middle-weight 20mm trail wheelsets and the sneaking suspicion that RockShox would be adopting the 15QR standard before long. As a light rider, I didn't know that I needed that much stiffness, and I wanted to maximize interchangeability between bikes.

There was another, secret, reason too. Last winter, a ride with Dan had me thinking. He was raving about how the change from a Manitou Minute and American Classic front hub to a Rock Shox Reba and DT 240 had improved the steering on his 29er. His feeling was that the 9mm DT Thru Bolt system was the key.

DT's RWS Thru Bolt is effectively a massive single-sided wing nut that runs through the hub (like a thru axle) and on which normal quick release dropouts (9mm front, 10mm rear) rest. The carbon-reinforced plastic handle can be repositioned to allow for good leverage (and to be tucked out of the way once fastened). DT claim up to a 50% improvement in clamping force over standard QR's. They also note that, as there is no plastic in the 'force flow,' RWS skewers are more consistent when faced with disc brake-generated heat.

While I was aware of the RWS system, I was under the impression that it was a DT-only option. Later, when converting my Fulcrum Red Metal 0 wheelset from 15QR to quick release, it occurred to me that the solid axle with pressed-in end caps would readily lend itself to an RWS retrofit (because the force of the RWS can't crush the bearings). I ordered up an RWS thru bolt and decided to make it happen.

In no more than 20 minutes, a friend with a lathe was able to knock the axle's 9mm nubs off and drill the end caps to just over 9mm using a T-sized drill bit in the tail stock. The thru bolt slid right in and the wheel was back together another 15 minutes later.

Though I'm reasonably sure that Fulcrum would recommend against the modification, I've suffered no ill effects from the change. The wheel spins just as beautifully as it did before the change and I've noticed no creaking or other movement. The RWS is no slower to mount or remove than a standard quick release and certainly looks good.

Now it may be a testament to the stiffness of the Revelation or a function of my own light weight, but I haven't noticed a major any difference in front end precision with the RWS mod. Looking around while writing this, there are a number of riders on MTBR who swear by the conversion, though (and I thought I was so clever). Still, it was an easy change (though the RWS thru bolt runs a steep $65) and an interesting exercise. The change may well have stiffened up my front end- but it wasn't noticeably flexy to begin with. It is something that I would certainly consider doing on an inherently flexier 29er, though.



1 comment:

Anonymous said...

Can this be done with RM3's?

Did you consider a 9 mm conversion for your back wheel too?

What diameter did you drill the end cap at 9.5mm, or 10mm etc?