Avid beltdrive dropnroll & C3 questions + pics

[overboard]

Hi. I chose to do a Avide dropnroll with C3 belt system + 8t drivers for a 3" track. More clearance and a choice of gearing, albeit at a premium over 7t.

Never did a d'n'r before, but havin a go should be fun....
My question to anyone who has done the beltcase install (anyone yet ?) is where do all the shims (2 steel, 2 aluminum) and the 2 steel brackets go ? I thought it would be intuitive once I got it apart, but it is not. Al shims are as thick as tunnel braces, steel are thicker, the brakcets are ~ 5 mm thick at bottom and 1.6 mm on top.
I did ask C3 (my part supplier) no answer, also awaiting a response from Avid.

Any insight ? Pics would be great

Anyhow, here are the pics of the brackets, as well as some overall C3/Aivd combination kit pics.

 

[overboard]

Got an answer

I received an answer from Avid - the bracket is for the rear skid mount, the shims are for tunnel bracing where the front skid bolts go. See attached.

 

[Pownar]

Im thinking about a drop n roll this winter and am curious as to why you didn't go with the CMX since it does both?

 

[overboard]

Hi. Avid and C3 teamed up to give the one shot deal too (the Avid case is modified for C3 and the C3 Syncro is modded to fit inside the Avid case).
I don't like the idea of a blown belt resulting in no brakes but hopefully nothing ever happens. C3 is relatively local for me and had the parts.
I didn't like the brake disk hangin down way at the bottom on the CMX.

I have it together now and there is about 1" clearance for the 3incher with 8t 3p sprockets.

 

[overboard]

Well over 1" clearance

Installed with 3" + 8t 3p drivers. My math showed I gained 5.6 mm clearance from stock with the dn'r, whereas I would have lost 4.6 mm with 7t 3p.
I did 3/4" dn'r for the skid, fitting into the pre-marked holes in the front skid mount, and using avid's supplied brackets for the rear + small allen head bolts.
Plenty of clearance above the guide bars (I thought they may rub by not going full 1" drop). The 3/4" roll worked perfect for track length going from 163 to 162".
I hope it ends up performing well and being worth the time and effort above the 7t route.

 

[Sway14Pro]

I too did the avid drop and roll C3. Problem is Its a 2:33 gearing. Combined with 8t 3" pitch drivers, it gives me around 130km/h track speed. So by dropping back to the 7t 3" i get about 111km/h. A little closer to the 105km\h track speed I'm Looking for.

 

[overboard]

Ratios & methodology

I went from stock to 8t 3p. I gain 5% due to larger gear. I reduced from 2.1 to 2.5 ratio with C3, (minus 19%). So I'm going to be at ~ -15% from stock.
Going 8t 2.86p to 7t 3p = -8.2%, which I did not figure was enough so a re-gear was in order, hence C3. I'm only runnin SLP stage 3 so the turbo or BB power won't be there.

2.1 to 2.33 (-11%) + the 7t 3p (-8.2%) ~ 19% which will be ~ 4% lower than mine. I could not get a lower ratio with C3, but I would have installed it were it available. It would be interesting to see what works better - more clearance with 7t or more efficiency with 8t. Where is the line is between optimal clearance and efficiency.

 

[Sway14Pro]

Yeah when I talk to them the best I could get was a 2:52 ratio with the pro. That still only dropped my track speed down to around 120km/h. Considering where the pro power sits, I didn't feel that was good enough. So I thought I would find a happy medium between efficiency and gearing. All that's left to do now is ride it and see