CyclePro Sinner trail bike

 

It is quite a rare bike as it was only manufacterd in 2002 to 2003 during the era when the brand was owned by the Swedish Hallman company.

Brief history of the brand can be found on the following page http://www.cykelhobby.com/cyclepro.html At the time it was labeled as a freeride bike but on todays standards with 130 mm of travel it is more of a trail bike and I dont't think it would be wise to take it in a downhill situaton

 

 

The bike is built on an aluminium frame with rear suspension. CyclePro called the suspension design as StarLink, which is very close to a Virtual Pivot design. It is realized very well with needle bearings on the upper and lower links and ball bearings on the mid link. The upper needl bearings are sealed with o-rings. The stock rear shock was a RST58, now replaced by a FOX RP23 Boost Valve. There are three travel settings on the shock link which translates to leverage ratios from 2 - 2.5 and 3. 

 

With the chosen suspension design these stress is concentated into two of the pivots. On the lower link the pivots seem to be under dimensioned which has caused the inner ring of the needle bearings to develop some wear. This is a non-standard inner ring with an inner diameter of 10 mm, outer diameter 12 mm and lenth 48 mm. The needle bearings themselves are standard units of type HK1210. After some research and luck I have found out that the identical suspension design is used in several bicycle models of Mongoose, the Teocali to name one. Mongoose owners have discovered this weakness as well one owner has put a lot of effort into designing an alternative made of a high-tech plastic material. His description can be found here http://www.fogma.co.uk/foggylog/archive/365.html This seems like a brilliant idea and my plan is to fabricate bearings out of POM.

  

The front fork is a Marzocchi Dirt Jumper 2 with 130mm travel, this model only has an adjustable pre-tension installed into a Cane Creek headset. It has a mixed groupset with Shimano XT rear derailleur, LX front derailleur and gear levers, Promax hydraulic brakes, Truvativ Husselfelt chainrings.

 

I have performed a major service by cleaning and regreasing all the pivots, changing brake fluid, and adjusting all the cables. Now I just have to wait that the snow sill melt away and the trails get rideable here in southern Finland.

 

RST58 MTB rear shock rebuild

This is a coil shock with hydraulic damping with adjustable rebound damping as well as a lockout. When I got the damper there was absolutely no compression damping, the rebound damping was fully functional. I couldn't find any information on this RST 58 damper, also tried contacting RST Europe but didn't get any response. So I searched for other damperes with a similar design to get an idea of how its put together.  Rockshox Super Deluxe seems similar in design and Vincent had dismantled one and posted a photo with all the parts, which helped me a lot: http://www.retrobike.co.uk/forum/viewtopic.php?t=178217 thanks for that!

I went on and disassembled the shock into pieces, shown in the picture below:

The root cause was obviously a broken O-ring of the upper reservoir cap. The compression side air and fluid escaped through the hole in the seal. Another problem was a worn rod bushing which caused the shaft to leak. I measured all of the installed o-rings, went on and replaced most of them. After replacing the bushing and seling rings I put the parts together and filled 5W fully synthetic shock oil through the hole where the compression damping valve screws in (note that the thread of the valve base is left-handed) I did several rounds of filling oil into the small aperture and moving the piston back and forth to purge air out. I filled as much oil as I could, now the shock works perfectly.