A Fully Enclosed Chaincase That Works

[Danneaux]

A poster on this forum did try running a 36T chainring in a 38T Hebie Chainglider. It was ugly. At the back of the chainring there was a clear, continuous gap where on his photographs we could see air between the tips of the teeth and the inside circumference of the Chainglider.

You're thinking of this post and photo, Andre: http://www.thorncycles.co.uk/forums/index.php?topic=4412.msg32313#msg32313

Best,

Dan. (...who wishes the hope/dream of a 36T Chainglider would come true and thanks John for the good thoughts)

[John Saxby]

Thanks, Andre and Dan.  Be interesting to know what Frank Revelo's experience has been, a year and a half later.  Your observation about dust entering the system via the exposed teeth at the rear of the 36T 'ring seems relevant, Dan, particularly for your use of the Nomad in the dusty conditions of Eastern Oregon & Western Nevada. Would the same problem hold in different conditions, I wonder--say, rain?  (I've valued the 'glider especially for the protection it offers to the front of the chain in the wet--and this, even with the protection from my 52 mm fenders with mudflaps.)

Think I'll resort to the strategy of Judicious Delay--just wait for a while--to see how another riding season plays out with my 38 x 17.  A 36 x 17 would give me slightly more than 5% lower gear-inches in each ratio, useful on steeper hills with a loaded bike, for sure.

Maybe I'll send a message to Hebie arguing the case for a 36T 'glider: "If you build some, they will sell."

[Danneaux]

Be interesting to know what Frank Revelo's experience has been, a year and a half later.

John,

As (mis-)sized, it didn't seem to work well for Frank. See...
http://www.thorncycles.co.uk/forums/index.php?topic=4412.msg32409#msg32409
Full followup report here:
http://www.thorncycles.co.uk/forums/index.php?topic=4977.msg47417#msg47417

Quote extracted from that last post:

Hebie chainglider failed to protect chain from dust, started to add drag as it became clogged with dust itself, and finally chainwheel began catching on the chainglider plastic, bending it out of shape and causing a rattling noise, which was annoying plus it might mask sounds of other bike components. So I threw the chainglider in the trash. This happened after exactly 3 weeks and 642 miles of riding on rugged dirt roads. Based on my experiences, I cannot recommend the Hebie chainglider for expedition touring.

All the best,

Dan.

[John Saxby]

Thanks, Dan, for that link.  FR's report on his 'glider is clear, pretty categorical & hence convincing; but also useful, with his suggestions.  Reckon I'll stay with my 38 x 17 for the time being, and I'll send a note to Hebie proposing they do a pilot project for a 36T 'glider. I'll suggest they contact Thorn Forum 'Glider Users for their focus group.

[Andre Jute]

Thanks for the link, Dan.

I'm not overly impressed with the gains of going to a 36T chainring if it means giving up the Hebie Chainglider.

For a tyre diameter of 29.45in (Big Apple 29er, you can adjust the numbers to suit your own tyres), I calculate leverage in gear-inch spreads, given as chainwheel x sprocket teeth, Rohloff low-high gear-inches:

38x16 19.5-102.6
38x17 18.4-96.6
36x16 18.5-97.2
36x17 17.4-91.5

Notice how close 38x17 and 36x16 are.

With a 26in wheel and a tyre diameter of 25.178in:
38x16 16.7-87.7
38x17 15.7-82.6
36x16 15.8-83.1
36x17 14.9-78.2

Ditto.

Good luck with talking sense into Hebie.

[Danneaux]

I'm not overly impressed with the gains of going to a 36T chainring if it means giving up the Hebie Chainglider.

Agreed it doesn't look like much on paper, but every bit counts when winching a hundredweight up a 24% goat trail in loose soil.

For me, the biggest gain from the 36x17 is it matches the half-step gearing on my favorite rando bike throughout the midrange, lopping off two (for me) uselessly high gears in favor of two lower ones. Everything else is pretty much the same to within a couple gear-inches, so everything feels "right" to me and my hummingbird cadence when switching bikes. I'd surely hate to give that up even for the weather-resistance and increased longevity afforded by a covered chain.

Of course I want it all, so still hoping for a 36T Chainglider. The flame of hope burns eternal.

All the best,

Dan.