Tensioner Redux

stilldoc · #1 11-04-2009, 08:35 PM

My stock tensioner broke so I'm giving this a try. The roller is from Tractor Supply and has been discussed on this forum but mounted on the seat post.

I'm using it bolted down, but it could also be configured to swing loose and attach to a spring.
Once I'm satisfied with the position, I will anchor the bracket to the chain stay with a self tapping screw to prevent rotation into the spokes.

(Looking at the photo while previewing this message, I think I might try facing it the other way, toward the back wheel, to get the bolt heads away from the chain)

stilldoc · #2 11-05-2009, 10:22 PM

Okay. Don't try this as it's pictured above. The roller bracket metal is not strong enough to withstand the torque created when starting the bike. Mine wound up like this:

I'm lucky it didn't rotate into the spokes.

**2door** · #3 11-05-2009, 10:32 PM

People underestimate the pressure applied to the chain under load; which is why so many have had the tensioner bracket come loose and be pulled inward, into the spokes. I've never tested the force on the chain at that point but it would be an interesting figure to know so we could pass along that information to new builders. Keep us informed on how your bracket idea is working. I'm glad the bracket is all that was damaged with your experiment. Thanks for sharing the photos.
Tom

**BarelyAWake** · #4 11-06-2009, 04:05 AM

I just wanted to say thanks for the follow up on this 'un - it's helpful to hear the problems as well as potential "solutions" and far too many of us forget to mention when somethin' goes south.

Looks like it's still a good 'un tho, if with just a stronger plate and/or a spring... you gonna mess around w/it more? If so - keep us posted

stilldoc · #5 11-06-2009, 09:23 AM

I like the bearing roller. It's smooth and quiet, so I think I'm going to try to find a way to attach it directly to the stock tensioner bracket with a grade 8 bolt. What I'm trying to accomplish is to develop a solution that doesn't require welding (since I don't have a welder) and uses easily acquired parts.

**BarelyAWake** · #6 11-06-2009, 09:42 AM

I agree - the bearing roller upgrade was a significant improvement on my bike

Jus' a FYI for those less inclined to DIY, Spooky and Dax both sell a replacement roller with a bearing (as I'm sure others do too) in case yer kit came with the older style w/o a bearing;

ThatsDax - Bearing Chain Tensioner
Spooky Tooth Cycles - Cartridge Bearing Chain Tensioner Wheel

Venice Motor Bikes · #7 11-06-2009, 09:58 AM

Most engine kits these days have the good bearing rollers in them!

stilldoc · #8 11-06-2009, 11:45 PM

Here's the latest rendition. It requires a 6mm bolt, a spacer, and washers.
Holding so far. I'll update the thread if it fails.

stilldoc · #9 11-07-2009, 05:05 PM

Holding up so far. Several startups and rode about 25 miles today.

**2door** · #10 11-07-2009, 05:18 PM

Quote:

Originally Posted by stilldoc

Holding up so far. Several startups and rode about 25 miles today.

Glad to hear it. Thanks for keeping us updated. Use caution however. You've already seen what can happen so keep a close watch on the bracket and make sure it doesn't move on the chainstay. You don't want all that steel to get pulled into your spokes.
I see a small hole in the stay. Is that from an earlier mount?
Tom