Re: [rootsradicals] ya got a Tensioner in mind?
- On 2012-03-09, at 1:19 AM, phishead_g wrote:
> so needless to say i'm pretty excited about installing all of this, but i have not gotten a chain tensioner. does anyone have a preference on tensioners? i have a kick back as well so i was thinking one with two iderler pullies on it will give me enough space...I've tried several, and at this point, what I recommend is recycling whatever derailer you have handy.
If the limit screws permit you to dial it in to the proper chain line, great, otherwise:
Get about 8 inches of brake cable (stainless preferred, because you are going to leave this forever), about an inch of outer housing with ferrules on both ends, add an adjuster barrel if you need to (many derailers have these already). Put cable into housing and barrel (with end jammed up against the end of the outer housing), stuff cable into derailer the usual way, position chainline roughly right (this may require an assistant), screw the clamp bolt tight on the cable, use adjuster barrel to fine tune. If you use an inline adjuster barrel, you'll need two little segments of cable; you want the adjuster to spin freely. I've done this once for someone else's XC IGH conversion and I left out the outer housing (because it was the first time and I didn't know any better) and the adjustment gets a little tricky with the brake nub directly on the adjuster, because it binds and twists the cable, which then tries to undo your adjustment. Once you get it right, clip off the excess cable, and crimp a cap on the end.
Why this is better:
1) won't inhibit wheel removal like the Rohloff tensioner
2) will get better chain wrap than the Surly tensioner
3) will give you plenty of clearance for a center stand
4) you have the option of running the chain pretty darn tight, subject to constraints of #1 and #3, if you want to.
5) probably cheaper than anything allegedly "designed" for the job.
6) you can be sure that it takes stock "derailer pulleys" for a rebuild, you have the option of some fancy ones, too.
- I have tried a bunch of different tensioners with my Nuvinci. I don't have a kickback, so I can't say how I would accomodate it, but what I have now works very well.
On the older Nuvinci the vert. dropout kit has a no-turn plate that bolts to the der. hanger. If the new one still has this plate you may want to move the tensioner off of the dropout to facilitate easier roadside repairs. So, I cut a very short piece of rear axle, and loctited it into the hanger to index the no turn plate, and the lock nut is all that is needed to secure the plate. That way I don't need to unscrew the plate from the dropout when I remove the wheel. I made an idler pulley that is clamped to the front cross tube (where the wideloaders mount). This let's me adjust the tension on the chain as it wears, but otherwise it's a non-issue.
--- In firstname.lastname@example.org, "phishead_g" <gussesg@...> wrote:
> so I had an xtracycle for years and loved it to death. I literary cracked the free-rad behind the dropout! so i got that welded and reinforced and than i snapped the fork inside the head tube, which flared out the head tube. so new donor bike. I wanted a frame that had a low stand over height but be up to the task of being strong enough to do the job. so i got just a radish front end! i intend on painting the whole thing my self (rattle can) and build a super smooth clean looking and trying to be somewhat cost conscious so i got a nuvinci n360 hub with wheel
> and a patterson metropolis for the front crank
> so needless to say i'm pretty excited about installing all of this, but i have not gotten a chain tensioner. does anyone have a preference on tensioners? i have a kick back as well so i was thinking one with two iderler pullies on it will give me enough space...
> thanks for your thoughts, when its all together ill post some shots
- Why not use der. cable and not brake cable? The smaller head won't pass through the barrel adjuster, if you want you can use a brass ferrule which won't bind then you don't have to look at any cable housing.
Just you $0.02. Sounds like you used MTB brake cable on your first attemp.
But David is on the $$ when he says tensioners get in the way when pulling off a wheel. I have a schummey-archer and it's a pain getting the wheel on and off with a 20t cog on the back. 18t cog is not much easier. Plus the way you adjust the tensioner I have is to use spacers on the fixing bolt to move the pulley into alignment. Not exactly precision work and the fixing bolt is only so long which means I have limited range of adjustment. Chain wrap with cheap tensioner is generally not as good as a der. and with the extra torque, you want as many teeth engaged as possible.