Wednesday, 20 March 2013

Single speed MTB crank sets - mechanics rant !

Just recently I up graded my stock crank set that came with the 2013 Kona Unit - why you ask ?. Well as a bicycle mechanic I was fed up with the left crank arm coming loose after a 20 min commute into the city  plus there was no way I would have ridden any distance on a crank set that continually works itself loose every day. The crank set that came on the bike uses the now popular style of external BB with an alloy crank bolt that provides the pressure to push the left hand crank arm onto the bearing face , this system only uses a 5mm allen bolt key for adjustment on the main crank bolt plus it has two opposing 5 mm crank bolts which are supposed to lock the crank arm in place. Sounds good , sorry but even though the system sounds like it should hold the cranks on tightly without any trouble it does not !. The main thing missing from the design is the stopper plate which is a Shimano design, the stopper plates main use is to firmly hold the opposing 5 mm allen bolt in position to stop it moving and it does this job very well. The stopper plate system in employed on many higher grade road and MTB crank sets and works very well. You can see the stopper plate in the Shimamo tech document pictured below.


The crank set I purchased is the new 2013 Shimano Zee crank set which has been designed for downhill racing and general MTB single speed applications where you need a good solid crank set in 104 BCD but do not require the added cost of a higher grade such as Shimano Saint etc. It uses the same system as the higher grade with a more basic finish. And is available for 68mm & 73mm BB shell diameters . The Shimano Zee crankset that I have recently fitted to my Kona unit is the same as the crank set pictured below


Of course I was considering changing the BB to a trad square taper and fitting either an older Shimano or Race face crank set or going nuts and ordering a nice made in the USA - White Industries or Paul Components crank set , but as I am not racing this bike I could not justify the added expense of a made in the USA crank set when the above Shimano crank set will do the job perfectly for a reasonable price. 

 I did receive some tech advice from the manufacturer of my old crank set , but putting a bit of loctite on the offending alloy bolt is not the best solution when that particular model crank set has been widely causing problems now for several years and is still fitted to some complete bicycles. 

So what brand of crank set did I recently throw into my rubbish bin at work along with all the rusty chains, clusters and old tyres - here is a clue to the manufacturers name ! 

Fucking   Shit   Accessories        
 

1 comment:

Doxrides said...

Future Shimano Advocate