Home > Bike Types > Mountain Bike

Misfit Psycles “Boner” (It’s Not What You Think) Single-Speed Chain Tensioner

8 Comments
Support us! Bikerumor may earn a small commission from affiliate links in this article. Learn More

I am haunted by the voice of Misfit Psycles owner Peter Keiller. Whenever I begin to type “Youtube” into my browser address bar, for whatever reason, it auto-fills directly to the 2007 Dirt Rag T.V. interview with the Canadian Independent frame-builder — “Alright we are with Peter…uh…Peter Keiller.” According to the interviewer Peter is “one of the guys on the edge influencing the center.” And if his new, prototypical single-speed chain tensioner does what it’s supposed to do, he is definitely going to be doing just that. I first caught wind of the funky, plastic (yes, plastic…wait for it) tensioner out at the Breck Epic this past August. At that time it was merely a doodle on a piece of graph paper, but now it is a full-fledged, seemingly functional prototype which is currently being ridden by Peter himself. If it can withstand the beating that such an enormous and belligerent man (Peter makes me wonder why Canada hasn’t been in more wars) subjects it to; it will have no trouble dealing with the rigors of being ridden by a normal, well-adjusted, human being.

For photos and details about the “ACTUAL science and REAL-LIVE engineering” behind the product Canadian Small Frame-Builder Semi-Quarterly Magazine is calling “The second or third most potentially innovative product to come out of Canada since the Canadarm” click more…

This from Peter Keiller, the furious scientist himself on the technical aspects of the tensioner:

ENGINEER SPEAK

The Misfit Psycles “Boner” tensioner is designed to eliminate the main issues found in other tensioners typically available on the market.
The main feature of the tensioner is the flattened center span, which acts as a leaf spring-like cantilever. The leaf spring has been integrated into a “fixed-type” tensioner, with mounting points at the axle and derailleur hanger. The center section has been engineered with a specific stiffness and range, allowing enough flex to compensate for out-of-round chainrings, yet maintain enough chain tension to prevent skipping. The leads to a drivetrain with just the right amount of tension for quiet, smooth, worry-free operation. With careful material selection, this motion has been realized without additional springs or links, for simple, maintenance free operation, with a high level of durability. In addition, the relative simplicity of the design will allow for a more reasonable price than some of the fancier tensioners on the market. Finally, the design uses a derailleur-pulley style idler wheel with adjustable chainline, offering optimum efficiency and minimal noise.


PETER KEILLER SPEAK

Misfit Psycles sells a LOT of tensioners. We could sell more but we tend to discourage many applications due to the many draw-backs of the existing sort…spring loaded tensioners are FINE if you intend to convert your ride for the purposes of TESTING the waters of single-speed. As a long term solution…their relevance deteriorates. Anyone that might suggest differently just wants your 30$.
The next step up are tensioners in and around the 75-100$ range. While effective they don’t really fit for those looking to convert a second or third or dumpster ride. Enter the Misfit Psycles BONER. Using ACTUAL science and REAL-LIVE engineering the BONER takes only the best parts of all available tensioners and then mixes it in with some previously un-used materials and a proprietary design (patent even pending).
Easy to install and simple to maintain the BONER is the perfect compromise between what there is and what you can’t afford.
BONER is named after it’s designer Thomas WOOD and the fact that the material from whence it is made is only available in white…and it looks like a bone…but boners are more funny.


SRP 45$
Weight unimportant
Made in Canada
Availability December 2010


Subscribe
Notify of
guest

This site uses Akismet to reduce spam. Learn how your comment data is processed.

8 Comments
Oldest
Newest Most Voted
Inline Feedbacks
View all comments
rc
rc
13 years ago

Why would you need a tensioner on a bike with sliding dropouts?

Thomas
13 years ago

@rc: you don’t. This was just the frame we had available to do field testing on the tensioner.

Dicky
13 years ago

As a witness to the actual testing you see in the above photos Peter used the bike he had on hand when the prototypes arrived. He added a link of chain to create slack and then mounted the tensioner. He then rode the three day Crank the Shield stage race which served up some of the nastiest, muddiest conditions I’ve seen in a long time. The type of mud that destroys wheel and bottom bracket bearings in less than half a week was everywhere. I saw days and days worth of broken bike parts as the race went on. The Boner survived the whole time.

Tyler Benedict
Admin
13 years ago

Dicky, I think they put some Viagra in the plastic for that prototype.

Thomas
13 years ago

While I won’t reveal the secret composition of our plastic, I’m pretty proud of designing a Boner that lasted for 3 days without any trouble..

topmounter
topmounter
13 years ago

We don’t care what the composition is, just please don’t tell us if it comes from Trinidad.

j
j
13 years ago

People coming off multi-gear bikes need to give up the springy cog. Why go single speed if you are going to keep some kind of immobile derailleur on your bike.

Zoltan
Zoltan
13 years ago

It seems like a solution in search of a problem. There are already several excellent tensioners in the $45 range, like the DMR STS or the Rennen Rollenlager (plus they’re made from aluminum, not plastic). Also, rigid tensioners (not sprung) have already proven themselves and shown out of round chainrings and cogs are simply not an issue; if a spring was needed to handle them then eccentric hubs/BBs, sliders, and track ends wouldn’t work either.

I can only see this product being competitive if they leverage the cost advantage of plastic construction and offer them in the $10-$20 range.

Subscribe Now

Sign up to receive BikeRumor content direct to your inbox.

Subscribe Now

Sign up to receive BikeRumor content direct to your inbox.