Chain Keeper

dave2pvd

I built up my 2010 bike last weekend. I noticed that my trusty Deda Dog Fang wouldn't work on the down tube.

I was also a bit baffled that Specialized didn't include a dedicated chain catcher on the frame. Then again, what manufacturer does?

The space between crank spider and down-tube is an absolute chain eater. There is no bottom bracket housing for the chain to land on, like a more traditional frame. I could foresee considerable damage.

Before anyone brings it up: even a perfectly adjusted FD will drop a chain if one shifts without due care. If you race, this can be an issue. For casual cyclist, dropping a chain should not be a frequent occurrence, but can still happen once in a while.

Anyway, I worked with our head machinist here and we came up with the device, pictured. It's pretty simple, but effective. Easy to install.

Some details: CNC-machined 6061-T6 aluminum (sorry, no aluminium versions have been prototyped). Finish: brushed. Comes with an M5x25 Allen bolt and washer. Weighs a little over 10g.

More pics.

What do you think?

scottreynolds

dave2pvd wrote: »

What do you think?

I like it...

Caroline_ie

have you a patent for it?

dave2pvd

Caroline_ie wrote: »

have you a patent for it?

Caroline,

I hadn't even thought about that.

Dave

Caroline_ie

its' OK Just got one under my name ... you're screwed :P

Serioulsy though, I would even remove that thread until you have one. Tis the internets after all.

blorg

Looks good. Great minds though and all that

Murph100

Patenting it might be a little problematic methinks...


http://www.competitivecyclist.com/road-bikes/components/k-edge/chains.2510.html


Bloody nice job though Dave, any idea how much it would cost if you were to do a few for us here ?

dave2pvd

Caroline_ie wrote: »

its' OK Just got one under my name ... you're screwed :P

Serioulsy though, I would even remove that thread until you have one. Tis the internets after all.

Not bothered by it too much, TBH. Afterall, I am asking what people think, not if they want to buy one

Now, where's my paint gone? Time to paint 3 stripes on the sides of my shoes....

Caroline_ie

they stole Dave's Idea the feckers!

dave2pvd

Murph100 wrote: »

http://www.competitivecyclist.com/road-bikes/components/k-edge/chains.2510.html

Jaysus, $49! I had no idea. Plus shipping, of what? $10?

dave2pvd

blorg wrote: »

Looks good. Great minds though and all that

Nice to be compared to Kristin Armstrong!

Murph100

That'll will look crap, never catch on.... ya might as well paint a big swoosh on the sides altogether...:)

dave2pvd wrote: »

Now, where's my paint gone? Time to paint 3 stripes on the sides of my shoes....

dave2pvd

Murph100 wrote: »

Bloody nice job though Dave, any idea how much it would cost if you were to do a few for us here ?

Murph, I am a bit reluctant to go there.

Tell ya what, PM me if you want more information.

Murph100

Ah 'tis no big deal, one of the frames I'm looking at getting might have the same problem with my Deda Dog Fang, but realistically by the time you get the aluminium, pay a machinist for his time and use of equipment, it probably works out the same as the K-Edge one to be fair.

dave2pvd wrote: »

Murph, I am a bit reluctant to go there.

Tell ya what, PM me if you want more information.

blorg

Wiggle has them although cheap they are not.

I'm not sure if the idea is patentable even by K-Edge, I am not sure when exactly this is from but it is the same idea used by I think David Millar (remember he dropped his chain dramatically when running a single chainring during the 2003 TdF Prologue, consequently losing by under a second.)

Murph100

They are well worth the money if you cant fit the cheap as chips Deda one. I've been very thankful the few times my chain has hopped off, I was also able to get it back on the chainring without stopping ( Dont know if that would work with the K-Edge one though ).

dave2pvd

blorg wrote: »

Wiggle has them although cheap they are not.

I'm not sure if the idea is patentable even by K-Edge, I am not sure when exactly this is from but it is the same idea used by I think David Millar (remember he dropped his chain dramatically when running a single chainring during the 2003 TdF Prologue, consequently losing by under a second.)

Blorg,

The welded stainless steel route was a concept that I considered. The welder is on vacation though. Another concept was sheet-metal formed into an angle. End of the day, we had an idle CNC machine and a willing machinist It was a fun project. Especially the part where I kept fretting about scratches on my new frame! Great amusement was found by all concerned.

dave2pvd

Murph100 wrote: »

They are well worth the money if you cant fit the cheap as chips Deda one. I've been very thankful the few times my chain has hopped off, I was also able to get it back on the chainring without stopping ( Dont know if that would work with the K-Edge one though ).

I can't speak to how the 'other' one works. The idea with mine is that if the chain decides to make a run for it, it immediately gets guided on again. The gap between the 39 ring and the keeper is all of 0.5mm.

Murph100

Sheeesh, now they're all at it !!


http://www.roadcyclinguk.com/gear-news/rotor-front-mech-chain-catcher/4710.html

dave2pvd

Murph100 wrote: »

Sheeesh, now they're all at it !!


http://www.roadcyclinguk.com/gear-news/rotor-front-mech-chain-catcher/4710.html

That's pretty!

bbosco

Murph100 wrote: »

They are well worth the money if you cant fit the cheap as chips Deda one. I've been very thankful the few times my chain has hopped off, I was also able to get it back on the chainring without stopping ( Dont know if that would work with the K-Edge one though ).

The Deda Dog Fang was too small to fit around my seat tube so I just ran a cable tie through the holes where the screw normally goes and that held it tightly enough not to slip. It's a little bit ugly but it works.

blorg

dave2pvd wrote: »

Blorg,

The welded stainless steel route was a concept that I considered. The welder is on vacation though. Another concept was sheet-metal formed into an angle. End of the day, we had an idle CNC machine and a willing machinist It was a fun project. Especially the part where I kept fretting about scratches on my new frame! Great amusement was found by all concerned.

Must say, it turned out very nice for a once-off prototype, far nicer than Miller's one. Maybe you should consider a new career with a pro team

blorg

I was going to ask if one of these would be compatible with a clamp-on derailleur but I guess if your frame will take a clamp-on derailleur it will probably take a Dog Fang. IIRC I tried to get a Dog Fang onto my Focus Cayo (braze-on IIRC) though after I derailled the chain into the BB and it wouldn't fit for whatever reason. I think the seat tube flared out significantly as it neared the BB and was far too wide where the Dog Fang would need to go.

Lumen

Thanks for bringing this up Dave, been meaning to get one of these for the cross bike, lots of ideas now.

bbosco

blorg wrote: »

I was going to ask if one of these would be compatible with a clamp-on derailleur but I guess if your frame will take a clamp-on derailleur it will probably take a Dog Fang. IIRC I tried to get a Dog Fang onto my Focus Cayo (braze-on IIRC) though after I derailled the chain into the BB and it wouldn't fit for whatever reason. I think the seat tube flared out significantly as it neared the BB and was far too wide where the Dog Fang would need to go.

Actually, I was going to say that mine has a clamp-on derailleur but wouldn't take the Dog Fang, but then remembered that the reason was not the diameter of the tube, rather that I needed to place it at the point where the (pretty chunky) tubeset badge is stuck to the tube. The cable tie approach should work on pretty much any round tube though.

dave2pvd

bbosco wrote: »

Actually, I was going to say that mine has a clamp-on derailleur but wouldn't take the Dog Fang, but then remembered that the reason was not the diameter of the tube, rather that I needed to place it at the point where the (pretty chunky) tubeset badge is stuck to the tube. The cable tie approach should work on pretty much any tube though.

And that's it. The lower part of the down tube on the SL Pro has a massive, almost square cross-section. At the bottom, it sweeps out-board towards the outer edges of the BB shell. You wouldn't have a snowball's of getting the Dog Fang on there.

el tel

I need a chain hanger/boss that will fit to my RH seat stay to hold the chain up out of the way for easy removal and fitting of the back wheel. My steel frames all have one but not the other bikes.

dave2pvd

It's been a while. I thought I'd post an update.



I put the CNC machine to work some more.
Aesthetic improvements: All edges are now chamfered. A channel has been routed along the length of the part.
Functional improvement: On the leading edge, there is now a heavy chamfer to improve chain guiding.
All these design features mean less weight. Although to be honest, this weighs about as much as a sneeze.
Now if only I could anodize it gold.....:cool:

dave2pvd

It's on Cycling Adverts.

See here.

Limited quantities. Get one while you can....