>60T large chainrings - where to buy?

[neptronix]

So i know a lot of guys with recumbents have these monster size chainrings on em..
But i have google searched for hours and just can't find where the hell people are buying them!

I am looking for a 130BCD 60T-66T 5 hole chainring, preferably in 1/8 ( single speed / BMX ).

Something that would fit the recumpence / ffrtrikes adapter..

http://www.outriderusa.com/Chainring-Adapter-130mm-BCD-p/11chainringadapter.htm

 

[Chalo]

I am looking for a 130BCD 60T-66T 5 hole chainring, preferably in 1/8 ( single speed / BMX ).

You're not likely to find a 1/8" ring in that tooth count-- mainly because most such rings are used on multi-speed bikes, but also because a narrow 3/32" chainring works with either width chain. The forces on such a big ring in its intended use are low, and articulating angles at the chain links are very small. There isn't really an advantage to the wide tooth kind in normal applications, even if there may be some advantage in your case.

Here are two online sources:
http://www.vueltausa.com/se-chain-ring-130mm-38-60t-1.html
http://www.hostelshoppe.com/cgi-bin/readitem.pl?Accessory=1016049820

 

[neptronix]

I saw the 60T vueltausa one. They top out at 60T. I'd like larger. 3/32 might not be a deal breaker but i'm not sure if they'd hold up long term. I'll be pushing 3-9kW like the big boys at outriderusa do with their large Astro drive systems.

 

[mdd0127]

If you're running 3-9kw, just go to 219 chain. You can get more gearing in a smaller/lighter footprint and have a drive system that will last forever.

Asuza Engineering can sell you driven sprocket blanks at a very reasonable cost and even do custom sprockets. Comet Karts has driver sprockets starting at 10T. A 219 65 tooth sprocket is about the size of a 40t bike sprocket (roughly).

http://www.azusaeng.com/
http://www.cometkartsales.com/store/sprocket/dd.htm

PM Kin for a non biased opinion on the wear characteristics on a properly setup 219 o-ring drive train. No visible tooth wear or chain stretch after about 2200 offroad/highway mixed miles on a 3220 setup sold me on the 219!

 

[hjns]

HoV made a 63T for me. Very happy with it. One may ask him to create another....

 

[Chalo]

I saw the 60T vueltausa one. They top out at 60T. I'd like larger. 3/32 might not be a deal breaker but i'm not sure if they'd hold up long term. I'll be pushing 3-9kW like the big boys at outriderusa do with their large Astro drive systems.

You can get custom sprockets for not much more than stock sprockets would cost you in the same sizes. And then you could probably spec the tooth width of your choice. These folks offer 61t-69t for $60, with larger sizes available:
http://www.kingssalesandservice.com/category/raw-aluminum-sprockets/

You may want to ask about the plate thickness, too. A big diameter sprocket on a small diameter mounting pattern will be stiffer and less likely to unship the chain if it is a little thicker than normal. They may only have one plate thickness to work with, but it can't hurt to ask.

 

[neptronix]

Did you see my video about kingssalesandservice? i found the company that makes their sprockets and will never talk to or advocate for that company again..

However, said company is not the easiest to deal with.

 

[Chalo]

Did you see my video about kingssalesandservice? i found the company that makes their sprockets and will never talk to or advocate for that company again..

However, said company is not the easiest to deal with.

Good to know, just in case I'm in the market for a huge sprocket.

I used to make my own sprockets when I had a giant CNC mill at my disposal. The biggest one I made for myself was a 144t sprocket for #25 chain (so the same pitch diameter as a 72t bicycle sprocket). I used .090" plate, but then I was only using a 24V 400W motor to make it go.

EDIT:

Oh, now I remember-- they were the ones who gave you normal industrial hole clearance on your part, and you thought they'd done you wrong. If that's the problem with them, it's hard for me to see a problem. I'm guessing there's more to it than that?

 

[neptronix]

If you're running 3-9kw, just go to 219 chain. You can get more gearing in a smaller/lighter footprint and have a drive system that will last forever.

Asuza Engineering can sell you driven sprocket blanks at a very reasonable cost and even do custom sprockets. Comet Karts has driver sprockets starting at 10T. A 219 65 tooth sprocket is about the size of a 40t bike sprocket (roughly).

http://www.azusaeng.com/
http://www.cometkartsales.com/store/sprocket/dd.htm

PM Kin for a non biased opinion on the wear characteristics on a properly setup 219 o-ring drive train. No visible tooth wear or chain stretch after about 2200 offroad/highway mixed miles on a 3220 setup sold me on the 219!

Thanks for the pro tip!! I would have never thought that Azusa did custom machining. Looked at their page and didn't see any mention of it. It sounds like i can send them a 130BCD chainring as a template and get a #219 cut out to the bicycle chainring pattern. The price is super super reasonable - like $35-$40.

I called comet kart and they say that their sprockets are designed around tapered shafts. machining to 15mm internal and 7/8" for the drive sprockets is not possible according to them. They must not be the manufacturer - or are just unwilling to take the job on.

How about #35? would that be a suitable alternative? I have some super tiny #35 sprockets already..

 

[neptronix]

Oh, now I remember-- they were the ones who gave you normal industrial hole clearance on your part, and you thought they'd done you wrong. If that's the problem with them, it's hard for me to see a problem. I'm guessing there's more to it than that?

Not this argument again...

There's no such thing as "normal industrial hole clearance" for a 9 hole rag joint motorbike sprocket. The whole assembly depends entirely on tension to the spokes, so you are expected to slop it around until it's lined up correctly. I pulled a rag joint sprocket off a motor bike wheel once and found really small bolts inside. It's designed this way so you can move it around significantly around the spokes to get everything to line up...... this is the stupidest drive mechanism design i have ever seen, but consider the needs of a 50cc 2 stroke motor which is typically what's on these gas bikes.

So on that kind of design, slop is what you want. 8.5mm holes are probably drilled on the kingssalesandservice parts to be compatible with the typical ragjoint drive sprocket. But no properly sized bolts are supplied, nor could i find any after an exhaustive search. This might be OK on a gas motor still - since they are not going to produce a hundred foot pounds of torque from a dead stall, where drive components are most stressed. The tension of the bolts might hold things fine for a gas motor with a clutch that evens out the initial torque. But when you are pushing 100-200ft lbs of torque, how well are those thin little bolts going to hold that? if anything comes loose, there's going to be trouble since the sprocket will rock radially about 1-2mm, then start rocking axially and likely throw your chain off.

I have never bolted on a chainring onto a bike and had to index it to get rid of radial misalignment. You shouldn't have to do that with a drive component which will handle much more power and much higher RPMs than what a crank will see.

And for the customer service - get the guy on the phone and you'll see why i never want to deal with him again. :lol:

 

[Tommy L]

Subscribed! Thank you!

Tommy L sends....

 

[Chalo]

It's true that rag joint sprocket mounting is almost the opposite of engineering. It's like they tried using JB Weld, then baling wire, and then settled on rag joints because they didn't fall apart immediately. In my observation, the gasbike crowd is characteristically wired that way (even when they're not slobbering drunk). A chimp with a crescent wrench would fit right in.

When I've mounted rag joint sprockets for folks, they've been equipped with 6mm fasteners. 8.5mm holes would be unusually large for that size fastener, but workable with big washers and low fastener tension such as in a rag joint application. I assumed that the sprocket you were dealing with was intended for 8mm or 5/16" fasteners. Customary clearance on a 5/16 hole is 1/32" (0.8mm) over the nominal fastener size.

There are a lot of bicycle chainrings that have, if not 0.5mm, then close to that much clearance around the bolt holes. It's normal to have to rotate them in the direction of the chain pull to center them before tightening. Any ring you find 60t or larger would most likely be drilled to a tighter tolerance like 0.1mm over, just because it's a specialty item and would most likely not be punched or stamped.

 

[neptronix]

Speaking of Tommys...

I got off the phone with Tommy at outrider aka ffrtrikes and they have a bit of funky news.
The recumpence 130BCD chainring adapters may or may not work on 24" wheels due to the major inwards offset VS. the angles of the spokes. They were designed with 20 inch trike wheels in mind.

I believe that if the adapter is just a little off, then a 1-2mm disc brake spacer will "make it right". I will be the guinea pig on this one and i am ordering one of these adapters today.

I have a DXF file ( thanks Sonny Yalung ) for a 1/8 66T sprocket that can be printed at bigbluesaw, but the price is $120 for just one part. If 5 or more are made, the cost is around $40 each.

I am wondering if there is any interest in this sort of thing. I could do a group buy and get the cost down.

The reason i chose 66T is because a 10-15T #410 sprocket ( you can find them @ staton-inc.com, and the owner can even custom machine them to various bores ) can get you 6.6:1 - 6:1 - 5.5:1 - 5.0:1 - 4.4:1 ratios.

I could also do #35. Would that be the better route? it is far easier to find sprockets for #35 than #219. But nowhere near as easy to find tensioners ( just a bike derailleur should work fine on #410-#41 ).

I am torn on which way to go. But i like #410 better because it can easily be repurposed for other bike things.
If y'all want to do a group buy then i will have to swing in the direction of the majority though. Anyone here who has got one chain drive bike running already has more experience than me :lol:

 

[neptronix]

BTW i took some measurements on my chainrings.
You are right, the hole tolerances is awful. I've measured up to 10mm.
However, there is a bit of a 'seat' on all of my larger ones, which is done to good precision.
Also, the chainrings also 'seat' against the crank.
That is why, despite the super loose bolt holes, you never have to worry about radial misalignment.. you never have to index them, etc. I've never encountered that.

Kingsalesandservice sprockets come with neither of these features.

Bad design. If i get sprockets made, i will make the 8mm hole 8mm. You will have to sand inside the hole a little if your 8mm chainring bolt does not fit. It's better than sloppy seconds. You wouldn't design a torque arm with 1mm of slop in it - your axle would be goners if you did that after a few hundred times you accelerated from a stall, hit regen, etc.

 

[mdd0127]

Replying from phone. Please excuse. I know nothing about 35 really never used it much. To run the kart drivers as drivens on a hub , you might be able to use a bmx driver type hub and have imachineshop make a driver adapter for you.

 

[Chalo]

BTW i took some measurements on my chainrings.
You are right, the hole tolerances is awful. I've measured up to 10mm.

10mm holes are for the tubular nuts (usually middle and outer rings). 8mm holes are for chainring bolts that thread directly into the crank arm (usually inner rings). The 10mm kind mostly fit closer than the 8mm kind, because they are supposed to fit to an outer diameter rather than to a thread.

If i get sprockets made, i will make the 8mm hole 8mm. You will have to sand inside the hole a little if your 8mm chainring bolt does not fit. It's better than sloppy seconds.

I just pulled a controller off of a base plate I made for it many years ago, when I was a meticulous machinist for a space program. I liked things to fit perfectly, and I had the skills and the machinery to deliver any level of precision I wanted. So the 5mm holes in this base plate were exactly 5mm in diameter. I can assure you without having to measure it, that these holes are situated in an exact rectangle, corresponding exactly to dimensions I measured from the controller I was mounting. The thing fits just so, and the controller can't slop around even before it's tightened in place.

The trouble with that is the controller was made in China. Its holes are pretty much 5mm in diameter and arranged in a very close approximation of a rectangle. The screws bind, and have to be backed all the way out of their holes even after the nuts are removed. If I'd only just made the holes in my base plate a little bit larger, instead of exactly the same diameter as the fasteners, the screws would slip right in and out.

Bicycle disc brake rotors don't locate on their bolts. They locate on a raised ring on the face of the hub. That way, only one feature of the hub and one feature of the rotor must be precisely sized and located to get good alignment. And you have smooth conformal mating surfaces, not a thread biting into the surface it's supposed to locate on. This is the way most bicycle chainrings work in practice. If they had to locate precisely on a five bolt pattern, that would give five times as many opportunities for the chainring not to fit the crank, or the other chainring that shares the same bolts.

Besides, fasteners are just fasteners. The shanks aren't always well centered on the threads, and neither are the heads. They are not always straight. You can assume that screws are as precise as dowel pins, but they are not. This can give you fits if you are depending on bolts to provide location, for instance.

 

[neptronix]

Good points...

What you're saying is that i may have these same indexing problems with the FFRTrikes adapter and a custom sprocket.

Looking at those pictures, i am also seeing that there are no parts of the adapter that index things. Or at least i can't see anything that will help that along.

We'll see how it goes. Will get measurements once the adapter comes in. There is very little info on it out there.

 

[MattyCiii]

Speaking of Tommys...

I got off the phone with Tommy at outrider aka ffrtrikes and they have a bit of funky news.
The recumpence 130BCD chainring adapters may or may not work on 24" wheels due to the major inwards offset VS. the angles of the spokes. They were designed with 20 inch trike wheels in mind.

I bought the chainring adapter I use on my NuVinci N360's from FFR. The first one I got had an offset about 3mm "too deep". I asked them if they could produce one that was shallower, and they did (My conversation was with Tom, mostly over email). This started back in Nov 2011, and they basically said they could do it, but it would have to wait till their next run of parts and could not predict when that would be. I ordered two, knowing the caveat about the indeterminate timeline, and I got the finished parts by Feb 2012.

Glad I bought two, I use one on each of my two bikes. Maybe they'll do custom one-off's again, with the same timeline caveat?

 

[jafa]

This shop in Holland has 130BCD 3/32 chainring of 60, 65 and 70'T in stock:

http://www.ligfietsshop.nl/en/webshop/kettinglijn/category/22-tandwielen.html

Got the 70T from them, in black, service was very good.