Using eccentric with TruVative Elita Crankset
09-04-10 | 10:12 AM
#1
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From: Montreal, Quebec
Using eccentric with TruVative Elita Crankset
After some 2000 km I needed to tighten the timing chain on our 2010 Co-Motion Primera. After looking at the manual and few posts here it did not seem to be a complicated thing. However, when I wanted to loosen the screws that hold the eccentric in place I noticed that the OEM TruVativ Elita crank makes them inaccessible (cf. photos bellow, which tried hard to take in level). So, I guess I will have to remove the timing chain and the crank, to actually turn the eccentric to the required position. Not too complicated, but I feel quite disappointed by the necessity of supplementary dumb hassle...
IMG_7202..jpgIMG_7201..jpg
IMG_7202..jpgIMG_7201..jpg
09-04-10 | 11:55 AM
#2
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Joined: Jan 2003
Posts: 324
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From: Tichborne, Ontario, Canada
Bikes: Trek 5200, Giant Rainier, Devinci Destination,Motobecane CF, Bike Friday family tandem, Bike Friday NWT
Boy oh Boy. And I thought I had a pita with the Cannondale eccentric. I'd give them a call.....an absolutely brutal design.
09-04-10 | 03:36 PM
#3
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From: Hollister, CA
Bikes: Volagi, daVinci Joint Venture
I assume with this style eccentric you only need access to one face . Why can't the eccentric be flipped around so the "screws" are accessible from the other side?
09-04-10 | 04:56 PM
#4
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From: Montreal, Quebec
Nope, there are 4 screws, 2 from each side of the eccentric, and all of them should be loosen. But this afternoon I bought an extra long and ball-ended allen key that could be used to torque screws even from a slight angle. Fortunately, the crank blocks the access just partially and the needed mis-alignement is small enough so that I was able to loosen the screws with this key without having to remove the crank. So the problem is solved. However, I am still wondering how they came up with such an unpractical design.
09-05-10 | 05:48 AM
#5
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From: Saranac Lake, NY, USA
The two ways to access the screws are either the ball end Allen wrench or to take a hacksaw and severly shorten the short leg of a conventional Allen wrench.
Why did they come up with the design? Because they are Co-Mo and need to differentiate themselves from other tandem makers
Why did they come up with the design? Because they are Co-Mo and need to differentiate themselves from other tandem makers
09-05-10 | 09:38 AM
#6
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From: Hollister, CA
Bikes: Volagi, daVinci Joint Venture
I suppose the Co-Mo design is lighter weight than what daVinci uses, but we have a single allen head screw on each of our two eccentrics and they seem to work just fine. Not that eccentrics need frequent adjustment, but four screws, two of which are difficult to access, seems like a PITA.
09-09-10 | 08:44 AM
#7
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The spider on our Ultegra cranks would have plenty of room to reach the allen heads....I'm guessing the design is a few years older than that crankset design?
However, our Robusta has the set screws (4) thru the bottom of the bottom bracket shell.
However, our Robusta has the set screws (4) thru the bottom of the bottom bracket shell.
09-09-10 | 09:45 AM
#9
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From: Just outside Kitchener, Ontario
Bikes: Nishiki Continental, Bilenky custom travel tinker, home built winter bike based on Nashbar cross frrame
Gee, you guys have me liking the design on our Bilenky more and more. It's essentially what Peter White shows on the Tout Terrain:
but with two Allen bolts, rather than three. To actually rotate the eccentric requires either a red or green pin tool, but there's room for that in behind the crank.
but with two Allen bolts, rather than three. To actually rotate the eccentric requires either a red or green pin tool, but there's room for that in behind the crank.
09-09-10 | 10:59 AM
#10
From my July 18th Blog entry regarding the Co-Motion 4-screw eccentric... I believe this would work in your situation as well.
There are worse designs.
Originally Posted by TG's Blog
The subtle nuance that exists with the combination of the 4-screw eccentric and the FSA SL-K cranks is that the SL-Ks molded-in crank spider precludes the ability to get any type of standard 4mm hex key (aka, allen key, hex or allen wrench) into the two left-hand screws used to secure the eccentric.
While it’s possible to use a ball-headed T-handle hex wrench to get to the screw sockets, you run the risk of marring the cranks & rounding a socket. Moreover, there’s a pretty good chance you won’t be able to generate sufficient torque on both left-side screws to keep the eccentric from creaking during hard pedaling efforts.
Therefore, what you need if you own a Co-Motion with this particular combination of eccentric and cranks — with or without the Gates Carbon Drive — is a 4mm hex/allen wrench that has had the shorter-end of the wrench cut down from it’ typical 1 inch length to about a half-inch.
The one pictured (below) is the one I cut down with a hand grinder in Tennessee to work on the Robusta. The shortened end allows you to slip it in behind the crank while still having enough ‘meat’ on the shaft to apply the needed torque to secure the eccentric bolts without damaging the key or socket flats.
While it’s possible to use a ball-headed T-handle hex wrench to get to the screw sockets, you run the risk of marring the cranks & rounding a socket. Moreover, there’s a pretty good chance you won’t be able to generate sufficient torque on both left-side screws to keep the eccentric from creaking during hard pedaling efforts.
Therefore, what you need if you own a Co-Motion with this particular combination of eccentric and cranks — with or without the Gates Carbon Drive — is a 4mm hex/allen wrench that has had the shorter-end of the wrench cut down from it’ typical 1 inch length to about a half-inch.
The one pictured (below) is the one I cut down with a hand grinder in Tennessee to work on the Robusta. The shortened end allows you to slip it in behind the crank while still having enough ‘meat’ on the shaft to apply the needed torque to secure the eccentric bolts without damaging the key or socket flats.
There are worse designs.
09-09-10 | 12:16 PM
#11
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From: El Paso, TX
Bikes: Co-Motion Speedster Co-Pilot
From my July 18th Blog entry regarding the Co-Motion 4-screw eccentric... I believe this would work in your situation as well.
There are worse designs.
There are worse designs.
For the newer Co-Mo's with external bottom brackets, I found the open-faced bottom bracket tool works very well to tighten the timing belt/chain and to hold it in place while the eccentric screws are being tightened. It doesn't take much force so there is no chance of loosening a properly tightened bearing.
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