Thorn Cycles Forum

Technical => Wheels, Tyres and Brakes => Topic started by: in4 on December 29, 2020, 07:03:27 am

Title: Chain glider advice
Post by: in4 on December 29, 2020, 07:03:27 am: I run 45 x 19 on my Mk2 Nomad. Quite happy with that. To use a chainglider I believe I’d need to change to a 42. If I did change would the difference between a 45 and 42 amount to much? Any thoughts appreciated. Thanks.
Title: Re: Chain glider advice
Post by: martinf on December 29, 2020, 09:10:39 am: The Chainglider rear part designed for Rohloff suits 15 to 17 tooth rear sprockets. It is compatible with the 38T, 42T and 44T front part.

With a large 19T rear sprocket you might be able to use the rear part designed for Nexus hubs, which suits 18 to 22 tooth rear sprockets. This is also compatible with the 38T, 42T and 44T front part. If you do try this, make sure that the rear part does not rub on the Rohloff hub and damage it, this was the issue that led to the introduction of the Rohloff-specific rear part, but at that time large sprockets for Rohloff hubs were rare.

I have a 19T sprocket on my Raven Sport Tour. Trial-fitting a Nexus-compatible Chainglider rear part on this suggests that it will not rub on the Rohloff, but it would need minor surgery to clear the seatstay on the Raven Sport Tour frame. And I would also need to change the current 50T chainring.

So if you want a Chainglider, you would have to change at least the chainring. 44T wouldn't change the gearing much.

An "approved" combination of 38 x16 would fit the Rohloff-specific Chainglider and give nearly exactly the same gearing as your 45 x 19.

Some chainrings are too thick to work well with a Chainglider. When possible, I prefer the Surly stainless-steel rings, these are thinner than most, stainless steel is supposed to be more hard-wearing than aluminium, and, like the thick aluminium alloy Thorn rings, they can be flipped to get more wear. But I have a couple of family bikes with TA Cyclotouriste rings for 1/8" chain which, despite being rather thick, also work OK with a Chainglider.
Title: Re: Chain glider advice
Post by: UKTony on December 29, 2020, 12:10:39 pm: Chain glider problems aside you might find the Rohloff gearing tables here useful

http://www.sjscycles.com/thornpdf/ThornLivingWithARohloff.pdf
Title: Re: Chain glider advice
Post by: JohnR on January 01, 2021, 10:18:05 pm: If you're in UK then these steel chainrings work fine with the Chainglider:
4 bolt https://www.sourcebmx.com/products/jet-bmx-4-bolt-race-chainring?variant=31801814712431&currency=gbp
5 bolt https://www.sourcebmx.com/products/jet-bmx-5-bolt-race-chainring?nosto=productcategory-nosto-1-copy&currency=gbp

I had to do a lot of searching to find a Chainglider-compatible chainring for my Mercury. More info at http://thorncyclesforum.co.uk/index.php?topic=13973.0 . You may find you need to cut a bit off the rear part of the Chainglider to clear the seat stay.
Title: Re: Chain glider advice
Post by: John Saxby on January 02, 2021, 05:24:52 pm: On stainless rings: I have used Surly stainless rings (38T & 36T) on my Raven-mit-'glider. They are very durable, and can be flipped for longer mileage. OTOH, I have found the production quality to be uneven (pun intended): the most recent 36T rings I have used have been ever-so-slightly oval, producing a noticeable tight spot in the chain, and have also been slightly uneven in the horizontal plane, giving me a slightly irregular chain line when mounted vertically on the bike.

So, I've switched to 36T alloy rings, made by Origin8 for Rivendell Bike Works in California. At first, I thought that these might be slightly too thick to use with the 'glider, but the toothed section of the ring is exactly 3mm. So that's OK. (To gain a wee bit more clearance, I also did more plastic surgery on my 'glider, removing 1 millimetre or so from the stiffening "collar" on both halves of the forward section 'glider where it is closest to the leading edge of the chainring.)

The Rivendell alloy rings are exceptionally well made: For the first time in my 2-wheeled life, I can't find a tight spot in my chain. And, the chainline is spot-on 54mm at every ring bolt. These rings cannot be flipped, however: the holes for the ring bolts are countersunk. That helps the all-around snug fit, of course.

Hope that's helpful, Ian, though I realize that the size of the rings I use differ from yours, and that Rivendell's products may not be available right now.

Cheers, John
Title: Re: Chain glider advice
Post by: PH on January 02, 2021, 05:36:43 pm: I have a question, just out of curiosity, apologies if it's already been answered somewhere.
I have no chainglider experience, I only know one person who's used it and they didn't keep it long. Does the efficiency, or noise, of a chainglider vary with chain tension? It's hard to imagine how it wouldn't and my experience with a Rohloff, and other hub gears, is that they run noticeably smoother with a slack chain.
Title: Re: Chain glider advice
Post by: Andre Jute on January 02, 2021, 10:43:40 pm: Quote from: PH on January 02, 2021, 05:36:43 pm
Does the efficiency, or noise, of a chainglider vary with chain tension? It's hard to imagine how it wouldn't and my experience with a Rohloff, and other hub gears, is that they run noticeably smoother with a slack chain.

The short answer is no to both your question and your further perfectly logical supposition.

I run a very slack chain inside a Chainglider on my Rohloff HGB and it has never bothered me either efficiency-wise or aurally. The proof of this pudding is to open the Chainglider after a few thousand clicks and note how much oil has rubbed from the chain onto the inside of the Chainglider.

(http://www.coolmainpress.com/miscimage/chainglider_inside_at_3500km_800pxw.jpg)

My Chainglider with 3500km on the chain, still on the factory lube, which at this stage is a soft oil, which just loves sticking to you fingers, your clothes, in fact any surface. There has been no service or cleaning of any kind. The chain is KMC X8-93. Notice how clean the inside of the Chainglider is.

Clearly, even a slack chain -- and, to repeat, I run my chain very slack -- doesn't rub on the inside of the Chainglider, so it is difficult to see where or how any inefficiency or noise ascribable to the Chainglider can arise.
Title: Re: Chain glider advice
Post by: ourclarioncall on January 03, 2021, 02:27:10 am: I want a rohloff , chain and chainglider

But I’m totally bamboozled by the rear sprockets and chainrings

Does the chainglider only fit certain combinations and Certain brands?

Is there like a standard universal combination that is tried and tested that would be a good recommendation?
Title: Re: Chain glider advice
Post by: Andre Jute on January 03, 2021, 04:16:45 am: Quote from: ourclarioncall on January 03, 2021, 02:27:10 am
I want a rohloff , chain and chainglider

But I’m totally bamboozled by the rear sprockets and chainrings

Does the chainglider only fit certain combinations and Certain brands?

Is there like a standard universal combination that is tried and tested that would be a good recommendation?

A Chainglider consists of two major and some minor parts. You don't need to worry about the minor parts as long as you choose the two major parts right. The two major parts are the sprocket cover and chainring cover, the latter having the runs of chain cover moulded with it as one piece.

There is a proprietary Chainglider dedicated Rohloff rear cover for the sprocket. It would be all right for Martin, who has experience of Chaingliders on several bikes, to mess around with the covers for Shimano or other hub gearboxes, but you, who don't yet know what's what in Chainglider land, would run the risk of scratching your expensive Rohloff HGB if you stray from the approved part. So buy the Chainglider sprocket cover made specifically for the Rohloff, of which there is only one, which takes all the approved sprockets. (Actually, there's another sprocket, but no one fitting out a touring bike would even consider it.) You can now choose between Rohloff sprockets with 15, 16 and 17 teeth.

Before you can choose the front Chainglider cover for the chainring, you must decide how many teeth the chainring will have, because there are three Chainglider front parts which each suits only one tooth count, 38, 42 or 44 teeth. Chainring tooth count and Chainglider front part must be an absolutely precise match or the mismatch will look horrible.

The three front parts of the Hebie Chainglider for 38, 42 and 44 teeth are each duplicated in a short and long version. It's not a big deal because the runs of chain covers must be trimmed to length anyway where they join the sprocket cover, and there is some overlap, but with an extra-long bike (like my 2m+ Kranich, for instance) or an extra-short bike (Surly Karate Monkey, IIRC) it could matter. In practice all that is required is for the bike builder or assembler to measure from the centre of the pedal axle to the centre of the rear axle, and to order the long or the short front part of the Chainglider for his choice of teeth on the chainring accordingly by a code letter for the length on the part number.

At this point, having chosen the number of teeth but not yet chosen the precise chainring your will use, you run into another minor complication, which is that the Chainglider is made to take chainrings of a fixed thickness, thinner than many desirable aluminium chainrings, like the Thorn one. Many of us have solved this problem by buying the Surly stainless steel chainring, but you should inform yourself of whether there is a Surly tooth count for whichever spider you want to mount it to. It's less of a big deal than it sounds, because suitable cranksets are readily and cheaply available, and you probably have something that fits already.

Another consideration with the crankset, either what you have or new, is that the Rohloff spec requires a pretty strict adherence to the approved chainline, but this is easily solved with the right axle length in your bottom bracket or even a few spacers.

All this repays care but is no more difficult than decisions elsewhere about your bike, for instance choosing the bike from the Thorn list that suits your body measurements and riding style.

I were you, I would choose 38x16 teeth, which is the default choice for many upmarket European bikes. For the longest time, and perhaps still, Rohloffs came from the factory with a default 16T sprocket, so it is very common. And 38x16 is, as Martin has pointed out, close to 45x19. Also, a Surly stainless chainring is available in 38T with bolt patterns for common spiders. That makes 38x16 an easy choice for you. It is also a very common starter combination, including with riders here who've since moved on to more exotic transmission combinations on their Rohloff, some requiring surgery. I used 38x16 for years and was perfectly happy, and changed only because after heart surgery I fitted a central motor which required a deep-dished chainring to make the chainline.

The chain is the least of your problems right now. I consider the KMC X8 the best balance between cost and performance, and others here also like it, but other chains also have adherents, such as the Connex chains I used before I switched to KMC.

If you decide to proceed as outlined in this post, ask and we can look up part numbers for you. On this page are some tables I used to decide that I would take the default 38x16T Rohloff transmission from among those which fit the Chainglider:
http://coolmainpress.com/BICYCLINGHebieChainglider.html (http://coolmainpress.com/BICYCLINGHebieChainglider.html)

Good luck.
Title: Re: Chain glider advice
Post by: Danneaux on January 03, 2021, 04:29:02 am: Quote
Does the chainglider only fit certain combinations and Certain brands?
Yes, I'll second what Andre said and and home in on one more caveat:

Choose your crankset's BCD/PCD (bolt circle) carefully when you order your bike. I am running a Deore crankset with 104mm BCD. Unfortunately, Surly stainless chainrings are not available in tooth sizes larger than 36t in a 104mm BCD and I am running a 36x17 combo. As was recently mentioned here, suitably thin steel BMX chainrings are available in larger sizes but tend to run toward non-stainless.

Needless to say I want a Chainglider too, but so far have been out of luck unless I change both bottom bracket (an expensive Phil Wood unit), chainring, crankset and sprocket to something closely equivalent to the ratio I have that will fit the Chainglider. Hebie might introduce additional sizes in the future. Alternatively, Surly may expand its range of 104mm BCD chainring sizes. I hope so. That way I would only have to buy a new sprocket and chainring to fit one of the existing Chainglider sizes/front-rear combinations.

Best,

Dan.
Title: Re: Chain glider advice
Post by: martinf on January 03, 2021, 09:29:27 am: A possible alternative for long transmission life without a Chainglider might be:

https://www.kmcchain.eu/10000km

Not tried these KMC components myself, and I am unlikely to ever need them for most of my bikes, which already have Chaingliders.
Title: Re: Chain glider advice
Post by: Matt2matt2002 on January 03, 2021, 09:40:10 am: Looks interesting, Martin.
I'll check the chain I have fitted in my Raven Tour.
It also has a Chainglider.
Title: Re: Chain glider advice
Post by: spoof on January 03, 2021, 04:30:36 pm: Hello in4/all,

I too have recently considered converting my MK2 Nomad to use the Hebie Chainglider as such messaged some of the lovely folk on here regarding their real world usage all of whom gave excellent advice.
I currently run a 40/17 teeth combination at the moment which I am very much a fan of in terms of usable low and top gearing. The closest ratio to this current setup that allows me to fit and use the hebie plastic shell will be the 38/16 combination (2.353 vs 2.375). As such I do require a new front chainring as well as new rear sprocket and very likely a new chain as well. The current chain is a shimano although I am used to the KMC brand that use quick links. Although I believe KMC quick links in the correct size are listed as suitable for use with shimano HG chains for example, I maybe wrong on this however, but re-using a not so old chain might be a valid option.

The latest rear chainglider part made by Hebie that is designed for rohloff hub sprocket cover is suitable for older threaded sprockets and also the latest rohloff splined sprockets that come with newer rohloff hubs. The later splined sprockets sit just 1mm further outwards so I don't think they will cause any issue when fitting a chainglider. They discontinued the old threaded style sprockets for Rohloff now but Thorn still manufacture their own branded compatible threaded ones which you can buy at the link here...

https://www.sjscycles.co.uk/sprockets/thorn-sprocket-for-rohloff-hubs-19t/

I noticed not much clearance looking at pictures of other users who fitted the chainglider to their Thorn Nomad MK2 bicycles. Indeed, the chain is already quite close proximity to the rear stays but others have seem to have done it so maybe the rear plastic doesn't cause collision with the frame work. It is on this basis why after research I decided to buy a 16T in the threaded sprocket style since many users with it fitted to their Nomad, at the time of posting, likely be using with this style rear cog. Sliding dropouts must have slightly wider rear stays as such a more generous clearance for allowing room for the rear hebie plastic and also infinite micro adjustment of their chain tensioning. This isn't quite the case with the Nomad MK2 EBB (solved with Nomad MK3) which has the recommended "pit stop" when the chain tension requires adjustment as to provide adequate spacing of dents made in the EBB shell. It did occur to me that adding a chainglider might possibly change this meaning that a stretched chain causing any issue inside the plastic shell might prove a problem which is good to find real world users feedback using them.
Grateful for any users advice on these topics, since I have yet to convert my Nomad to chainglider and if do decide, I might run my current setup out before doing the conversion. I use the Deuter pant protector for clipping in my trousers to save any best trousers getting oily.

Kyle
Title: Re: Chain glider advice
Post by: Andre Jute on January 03, 2021, 07:48:24 pm: So many experts and we overlooked a crucial point: The three front parts of the Hebie Chainglider for 38, 42 and 44 teeth are each duplicated in a short and long version. It's not a big deal because the runs of chain covers must be trimmed to length anyway, and there is some overlap, but with an extra-long bike (like my 2m+ Kranich, for instance) it could matter. In practice all that is required is for the bike builder or assembler to measure from the centre of the pedal axle to the centre of the rear axle, and to order the long or the short front part of the Chainglider accordingly.

I've added this point to my post above, without highlighting it unduly by an "Edit" notification in red. It's just another of the many small inputs into a Chainglider conversion, same as any other decision in the specification of a bike actually is a chain of small decisions.
Title: Re: Chain glider advice
Post by: Danneaux on January 03, 2021, 08:55:50 pm: Good man.
Quote
...In practice all that is required is for the bike builder or assembler to measure from the centre of the pedal axle to the centre of the rear axle, and to order the long or the short front part of the Chainglider accordingly...
...With the eccentric (on a Thorn) in the full-forward position to make sure of the maximum reach needed.

Best,

Dan.
Title: Re: Chain glider advice
Post by: PH on January 04, 2021, 01:59:06 pm: Quote from: Andre Jute on January 02, 2021, 10:43:40 pm
Quote from: PH on January 02, 2021, 05:36:43 pm
Does the efficiency, or noise, of a chainglider vary with chain tension? It's hard to imagine how it wouldn't and my experience with a Rohloff, and other hub gears, is that they run noticeably smoother with a slack chain.

The short answer is no to both your question and your further perfectly logical supposition.
Thanks Andre, I'm going to have to file this one away in the box labelled things I don't understand.
I had hoped that as I got older I'd start emptying it, but it just looks like I'll need a bigger box.
Title: Re: Chain glider advice
Post by: Matt2matt2002 on January 04, 2021, 05:31:48 pm: Quote from: PH on January 04, 2021, 01:59:06 pm
Quote from: Andre Jute on January 02, 2021, 10:43:40 pm
Quote from: PH on January 02, 2021, 05:36:43 pm
Does the efficiency, or noise, of a chainglider vary with chain tension? It's hard to imagine how it wouldn't and my experience with a Rohloff, and other hub gears, is that they run noticeably smoother with a slack chain.

The short answer is no to both your question and your further perfectly logical supposition.
Thanks Andre, I'm going to have to file this one away in the box labelled things I don't understand.
I had hoped that as I got older I'd start emptying it, but it just looks like I'll need a bigger box.

Ha ha. That made me smile. A nice smile. It rang a few bells.
Don't worry about not understanding.
Go with the flow - and good experienced advice here.
Ride the wave. With a bigger box.😉
And I can confirm Andre's comments, as a Chainglider user of some years.
Title: Re: Chain glider advice
Post by: ourclarioncall on January 06, 2021, 08:36:41 pm: Great reading gents

As you all will notice I’m a bit of a conversation starter . I light the fire and invite your firewood . Then I come back after a while to find to warm my hands 😄

Having 5 kids, I get pulled away
Title: Re: Chain glider advice
Post by: ourclarioncall on April 08, 2021, 12:00:23 am: Quote from: Danneaux on January 03, 2021, 04:29:02 am
Quote
Does the chainglider only fit certain combinations and Certain brands?
Yes, I'll second what Andre said and and home in on one more caveat:

Choose your crankset's BCD/PCD (bolt circle) carefully when you order your bike. I am running a Deore crankset with 104mm BCD. Unfortunately, Surly stainless chainrings are not available in tooth sizes larger than 36t in a 104mm BCD and I am running a 36x17 combo. As was recently mentioned here, suitably thin steel BMX chainrings are available in larger sizes but tend to run toward non-stainless.

Needless to say I want a Chainglider too, but so far have been out of luck unless I change both bottom bracket (an expensive Phil Wood unit), chainring, crankset and sprocket to something closely equivalent to the ratio I have that will fit the Chainglider. Hebie might introduce additional sizes in the future. Alternatively, Surly may expand its range of 104mm BCD chainring sizes. I hope so. That way I would only have to buy a new sprocket and chainring to fit one of the existing Chainglider sizes/front-rear combinations.

Best,

Dan.

So, if I want a chainglider , on a Nomad mk3, and I go with the advised 38 x 16 gearing ... then I have to get these 4 things to work together for compatibility ?

BOTTOM BRACKET
CHAINRING
CRANKSET
SPROCKET

For CHAINRING there is a surly 38T https://www.sjscycles.co.uk/chainrings/surly-110mm-bcd-5-arm-stainless-steel-chainring-silver-38t/ which I hear is thinner than Thorns and compatible with the chainglider

If I’m correct so far, what SPROCKET would work with this ? This ? https://www.sjscycles.co.uk/sprockets/13-rohloff-speedhub-50014-hub-gear-reversible-splined-sprocket-steel/
Title: Re: Chain glider advice
Post by: JohnR on April 08, 2021, 08:56:35 am: The standard Rohloff sprocket will be fine. What matters is the width across the teeth. Thorn's reversible aluminium chainring https://www.sjscycles.co.uk/chainrings/34-thorn-110mm-bcd-5-arm-reversible-single-chainring-332-inch-black is mainly about 5mm thick but is thinner at the teeth to fit a standard single speed chain (8 speed chains will also fit).

However, what you need to look out for is matching the cranks to the chainrings. The Surly chainring is 110 BCD (Bolt Circle Diameter see https://www.qbp.com/diagrams/tech_content/crank/bcd.html ) so you will need matching cranks. You also need to decide on the crank length. 170mm is a good starting place but, if you have a bike that you are comfortable with then check the distance between the centre of the crank and the centre of the pedal spindle. Cranks and bottom bracket will need to be compatible and the bike should use an eccentric bottom bracket for aducting the chain tension.

Finally, for now, it is advisible to use use a gear inch calculator such as https://www.sheldonbrown.com/gear-calc.html to compare the gearing of any bike you have with what you propose to order. 38T / 16T is, however, a good starting place as the rear chainglider part for a Rohloff can handle sprockets between 15T and 17T so you can change the gearing by about 6% up or down although this is only about half a gear step on the Rohloff hub.
Title: Re: Chain glider advice
Post by: ourclarioncall on April 08, 2021, 02:42:31 pm: Thanks JohnR

How’s this one?

https://www.sjscycles.co.uk/cranks/sjsc-110-pcd-alloy-singledouble-crankset-170mm/

If that is okay , then what about a bottom bracket? I’m clueless
Title: Re: Chain glider advice
Post by: ourclarioncall on April 08, 2021, 02:46:21 pm: JohnR

Just to clarify , are you saying the Thorn chainring you linked will or will not be compatible with the chainglider?

Cheers
Title: Re: Chain glider advice
Post by: JohnR on April 08, 2021, 06:14:01 pm: Quote from: ourclarioncall on April 08, 2021, 02:42:31 pm
How’s this one?

https://www.sjscycles.co.uk/cranks/sjsc-110-pcd-alloy-singledouble-crankset-170mm/

If that is okay , then what about a bottom bracket? I’m clueless
That crankset is probably OK and would work with a Shimano UN55 bottom bracket cartridge. However, the UN55 has been discontinued but I believe that SJS has found a substitute. Once you have decided on your preferred crank length and BCD / PCD (to suit your choice of sprockets) then Thorn / SJS can recommend suitable crank / bottom bracket combinations.

Quote from: ourclarioncall on April 08, 2021, 02:46:21 pm
Just to clarify , are you saying the Thorn chainring you linked will or will not be compatible with the chainglider?

The Thorn chainring will not work with the chainglider as it's too thick. I was just trying to point out that it's thinner where the teeth are. The chainglider encloses the chainring about 1.5cm in from the end of the teeth where the Thorn chainring is its full thickness.
Title: Re: Chain glider advice
Post by: ourclarioncall on April 08, 2021, 06:41:18 pm: Cheers JohnR

Is this the one you meant that’s out of stock ?

https://www.sjscycles.co.uk/bottom-brackets/107-shimano-un55-73mm-shell-english-thread-sealed-cartridge-taper-bottom-bracket/

If so , I see this is 73mm and there is another one that is 68mm that is in stock. I’m guessing these are important sizes that I need to be aware of to get my desired setup ?
Title: Re: Chain glider advice
Post by: JohnR on April 08, 2021, 08:58:51 pm: Yes, 68mm and 73mm are different sizes where the cartridge screws into the BB shell so they aren't interchangeable. There's also another variable: The crank axle length. Thorn recommend 107mm for the Rohloff hub but 110mm is also close enough to give an acceptable chainline for the Rohloff hub (chainline is the offset of the chain from the bike centre-line - it should be parallel).
Title: Re: Chain glider advice
Post by: ourclarioncall on April 08, 2021, 09:27:41 pm: JohnR

Is the crank axle a separate piece that you buy that’s different from the bottom bracket ? Or is the axle a part of the bottom bracket ?
Title: Re: Chain glider advice
Post by: JohnR on April 08, 2021, 10:15:14 pm: There's a bewildering choice of bottom bracket designs. Some are listed here https://www.sheldonbrown.com/cribsheet-bottombrackets.html . My Mercury is fitted with a UN55 cartridge (which has the crank axle built into it) which is fitted with square taper cranks. I have another (non-Thorn) bike which uses a GXP crankset which has the axle fixed to the right crank and the axle is independent of the bearing. The Thorn Rohloff bikes use an eccentric bottom bracket https://www.sjscycles.co.uk/bottom-brackets/thorn-raven-twin-mk3-eccentric-bottom-bracket/ which fits within the frame to enable chain tension adjustment.
Title: Re: Chain glider advice
Post by: ourclarioncall on April 09, 2021, 11:30:43 pm: I see on a thorn mk2 sjs have for sale https://www.sjscycles.co.uk/bikes/thorn-nomad-mk2-620l-black/ , the have specked a Tange Seiki 73mm English Square Taper Bottom Bracket - 107 mm

They have these for sale https://www.sjscycles.co.uk/bottom-brackets/tange-seiki-ln3922-73-mm-jis-english-square-taper-bottom-bracket-107-mm/

Here is the transmission specs

Transmission:
Thorn 104/64 PCD Triple Crankset MK2 - 175mm
Rohloff Hub 14spd 32h Black DISC 17T SLIM Carrier & Tandem Axle Plate
KMC E1 Rohloff Compatible 1/2 Inch x 3/32 Chain
Thorn 104mm BCD 4 Arm Reversible Single Chainring - 40T
Tange Seiki 73mm English Square Taper Bottom Bracket - 107 mm

Just a hypothetical question for now, but would this Tange Seiki work with the other parts I’ve mentioned ?

EDIT: I see the surly chainring is 110mm, does that mean the bottom bracket has to be 110mm ?
Title: Re: Chain glider advice
Post by: ourclarioncall on April 09, 2021, 11:37:49 pm: I from heard from Thorn today that they have no 26” forks left for nomad mk3 builds until March 2022 !!

so looks like my only choice is a mk2 in 620M or 620L

I do “just” fit into the height measurement for this frame which Thorn says is the equivalent of a 21” mountain bike frame.

So hmmm 🤔 need to ponder this one
Title: Re: Chain glider advice
Post by: Matt2matt2002 on April 10, 2021, 07:52:28 am: Quote from: ourclarioncall on April 09, 2021, 11:37:49 pm
I from heard from Thorn today that they have no 26” forks left for nomad mk3 builds until March 2022 !!

so looks like my only choice is a mk2 in 620M or 620L

I do “just” fit into the height measurement for this frame which Thorn says is the equivalent of a 21” mountain bike frame.

So hmmm 🤔 need to ponder this one

What is your time frame?
Less than a year to wait.
I love a good countdown.
More time to save up for extra goodies. And there will be lots.
The anticipation. Expectation. Marking those weeks and months off on the calendar.

Don't compromise. Get it right first time.
Title: Re: Chain glider advice
Post by: JohnR on April 10, 2021, 08:52:02 am: Quote from: ourclarioncall on April 09, 2021, 11:30:43 pm
EDIT: I see the surly chainring is 110mm, does that mean the bottom bracket has to be 110mm ?
No. The bottom bracket number is (I think) the axle length whereas the chainring is interested in the diameter of the circle for the bolts fixing the chainring to the cranks. Thorn use a square taper bottom bracket. This type means the crank axle has slightly tapered square ends onto which the cranks are fixed by nuts. Different square taper cranks would fit 110 (or 130) BCD / PCD cranks. There's a place called SourceBMX which sells 104BCD steel chainrings. I'm using one of those so I could fit a chainglider on my Mercury which has the same 104BCD cranks.

Yes, the Tange Seiki BB is compatible with the Shimano UN55. Only time will reveal if it is of the same quality.

It may be worthwhile watching Thorn's listing of ready-made bikes in case something suitable appears. They probably have some bikes as demonstrators on the basis that business should soon return to normal and people can visit the shop and try different bikes.
Title: Re: Chain glider advice
Post by: Andre Jute on April 10, 2021, 05:08:31 pm: I've put a short article in the Rohloff forum to relate all the components in the transmission of the bike near the bottom bracket together spatially, because it causes novices, and some old hands too, considerable confusion:
Specifying the BB axle length WRT the Rohloff HGB chainline (http://thorncyclesforum.co.uk/index.php?topic=14144.0)
Title: Re: Chain glider advice
Post by: ourclarioncall on April 12, 2021, 06:11:59 pm: Quote from: Matt2matt2002 on April 10, 2021, 07:52:28 am
Quote from: ourclarioncall on April 09, 2021, 11:37:49 pm
I from heard from Thorn today that they have no 26” forks left for nomad mk3 builds until March 2022 !!

so looks like my only choice is a mk2 in 620M or 620L

I do “just” fit into the height measurement for this frame which Thorn says is the equivalent of a 21” mountain bike frame.

So hmmm 🤔 need to ponder this one

What is your time frame?
Less than a year to wait.
I love a good countdown.
More time to save up for extra goodies. And there will be lots.
The anticipation. Expectation. Marking those weeks and months off on the calendar.

Don't compromise. Get it right first time.

Impatient me wants it now now now haha. But patient me can usually wrestle him down into subjection.

I need to figure out exactly what frame size I need and can’t find my tape measure which is no surprise in this chaotic house. I did measure myself before a while back but can’t remember exactly.

I know I can fit into 565L, 590L, and 620L

Speaking to a couple guys on YouTube , one is 6 foot and has the 565L and says the 590 is massive for him. Another guy who is just over 6 foot 1 inch has the 620L and didn’t like a smaller size. He DOES use butterfly bars tho which may have an effect on things.

So yeah, it’s quite fascinating how guys of similar height can vary so much. I guess there’s other factors than just height such as limb length.

I read in old thorn literature that the 620L is a rough equivalent of a 21” mountain bike frame , so that’s language I can relate to and understand. 590L = 19” frame, 565L = 17” frame.

I also have a 13 year old (sit at computer all day) who is about 6 foot and close to 16 stone and he is still growing , so just now he is about the same size as me but could be 6’ 6” by the time he has stopped growing and a 620L would be a fine fit for him then.

If I went for a 620L is could be a safe risk as I know my son could get the good of it and would love to get him into touring

There’s also a mk3 nomad size 580L that I’m sure would be a good fit for me but it’s derailleur. Not exactly what I want but possibly I could get it rohloffed

It seemed like most of the other nomad mk3 frames are sold out, well in my size anyway.

I could also buy second hand which I’m willing to do but it’s rare that the right bike comes up. Saying that, there has been quite a flood of thorn bikes on eBay recently so better time of year for buying

Probably best thing to do is find or buy a new measuring tape, get my measurements done accurately and get advice from Thorn
Title: Re: Chain glider advice
Post by: ourclarioncall on April 12, 2021, 06:17:49 pm: Quote from: Andre Jute on April 10, 2021, 05:08:31 pm
I've put a short article in the Rohloff forum to relate all the components in the transmission of the bike near the bottom bracket together spatially, because it causes novices, and some old hands too, considerable confusion:
Specifying the BB axle length WRT the Rohloff HGB chainline (http://thorncyclesforum.co.uk/index.php?topic=14144.0)

Good stuff Andre 👍 yeah it can bamboozle the old brain a bit. Can’t believe I d been riding bikes my whole life and only now have taken the time to try and understand how they work . Bikes are such an amazing invention!!
Title: Re: Chain glider advice
Post by: ourclarioncall on April 12, 2021, 06:18:59 pm: JohnR

Cheers again John, I think I get it all now , makes sense . Appreciate your patience with my conveyor belt of questions ;D
Title: Re: Chain glider advice
Post by: beagley on May 21, 2021, 04:43:53 pm: Sadly, the Chainglider didn't work out for me due to incompatible chainring. Hence, front & rear parts are for sale, in case anyone is interested (hope this is OK with the admins, please remove if not):
https://www.ebay.co.uk/itm/174776547253 (https://www.ebay.co.uk/itm/174776547253) Front (38T)
https://www.ebay.co.uk/itm/174776547625 (https://www.ebay.co.uk/itm/174776547625) Rohloff 15-17T - Rear
Title: Re: Chain glider advice
Post by: JohnR on May 21, 2021, 10:46:30 pm: Quote from: beagley on May 21, 2021, 04:43:53 pm
Sadly, the Chainglider didn't work out for me due to incompatible chainring.
I bought a chainglider-compatible chainring from https://www.sourcebmx.com/products/jet-bmx-4-bolt-race-chainring.
Title: Re: Chain glider advice
Post by: John Saxby on May 22, 2021, 02:05:47 pm: I've bought 'glider-compatible chainrings from Rivendell Bike Works, here:
https://www.rivbike.com/collections/cranks-bbs

Mine is the 36T x 110--I bought two a year-plus ago, as future-proofing--but of course the 38T would fit as well.

These are lovely alloy items, made for RBW by Origin8. The toothed portion is 3 mm exactly, so fits the 'glider. I did an additional bit of cosmetic surgery on my 'glider to reduce any possible friction further still, details on request.
Title: Re: Chain glider advice
Post by: Matt2matt2002 on May 22, 2021, 06:40:24 pm: Details please, John.
Title: Re: Chain glider advice
Post by: JohnR on May 22, 2021, 06:56:53 pm: Quote from: Matt2matt2002 on May 22, 2021, 06:40:24 pm
Details please, John.
Which John?
Title: Re: Chain glider advice
Post by: John Saxby on May 22, 2021, 09:38:57 pm: Cosmetic surgery on my 'glider, Matt:

(I realize that this is desecration for some, but in mitigation, yer honner, I did it only 'cos Hebie doesn't make a 'glider designed for a 36T ring.)

Two bits:

First, to accommodate my switch to a 36T ring: (you don't need this, I think -- your ring is a 38T item, no?) I cut out the rear portion of the front circular section, the part encasing the rear part of the chain ring. Makes no noticeable difference that I can see in dirt'n'crud finding its way into the 'glider. As a precaution, I wrap a couple of turns of plastic electrical tape around the upper and lower runs of the 'glider, close to the ring itself.

Second, for the 36T Rivendell alloy ring, 3 MM: (The Surly 36T steel ring is slightly thinner, so doesn't need this extra attention. OTOH, the Rivendell ring gives me a chain with no tight spot, first time I've seen that in a lifetime of riding chain-driven two-wheelers.) So: on the inner faces of each of the two clamshell halves of the front portion of the 'glider where it encases the front part of the chainring and the chain itself, there's a small collar, about 2 - 3 mm high. As the 'glider encases the front portion of my Rivendell ring, that collar sits just over the toothed portion, and close to but not touching the thicker part of the chain ring below the teeth.

I used a sharp knife to remove the collar on each side, just to ensure that neither the teeth of the ring nor the portion just below the teeth rub on the 'glider.

Again, no noticeable entry of crud.

(But there is a noticeable weight loss on steep hills. ;) )

Hope this helps, Matt. I could take a picture if my words don't suit -- don't hesitate to let me know.

Cheers, J.
Title: Re: Chain glider advice
Post by: Matt2matt2002 on May 23, 2021, 10:01:31 am: Thanks John.
All clear now. Alles ist klar.
Nice tip re the electrical tape.
Good memory, I do indeed run a 38 front ring. Surly ,thin.
I recently purchased a replacement although I haven't flipped yet. I don't have the figures in front of me for its milage.
I guess these things are eye balled for renewal?
Milage/ conditions etc must be wear factors?
I've not heard of a measurement guage.

18 months after buying the Raven, second hand in Feb 2013 ( but with few miles on the clock ) I embarked on my self supported north to south end 2 end of Scotland trip.
I took the ferry from Aberdeen to Shetland and visited Muckle Flugger, the furthest point North in the British isles.
On my way back to my accommodation on Yell the chain began skipping the front ring. In fact I could not peddle at all. No grip whatsoever.
I had to push/ walk for 12+ miles.

Long story short; the 1 bike shop in Lerwick searched through a junk box out back and found a compatible replacement.
I was thinking I'd have to ferry home to Aberdeen but he saved my bacon.
This was pre Chainglider days so no comparability issues but was lucky he had one to fit my crank/ BB.

I managed to continue my tour South to the Mull of Galloway.
I wish I'd taken a picture of the worn ring but I recall the mechanic mentioning sharks teeth!