Another Chainglider post 😊

[ourclarioncall]

It’s everyone’s favourite topic . Again. lol

Okay, apologies , I’m sure I have already asked these questions before but haven’t a clue where they are. Did a keyword search but couldn’t find my old participation.

I’m considering a nomad 2 or 3 with chain . I printed off Thorns 72 pages of info and going step by step through it (again ), but with a bit more focus on finalising spec decisions

I want a chainglider , but from what I’ve read , getting all the bits such as sprocket /chainring to work together is challenging

Is there a tried and tested combo that we could say , well we know this works so you could get that

Or am I needing to compile a list of specs that other users have which work for them , but some parts may be dated or unavailable?


Cheers

[WorldTourer]

You said you want a belt drive and a Chainglider, but Chaingliders cannot be installed on belts. Nor would there be any reason to – belts do not need to be kept clean from grit attracted to oil like chains do.

[ourclarioncall]

Worldtourer

Oops, sorry, meant chain not belt

Will go edit it

[Danneaux]

...Or am I needing to compile a list of specs that other users have which work for them , but some parts may be dated or unavailable?

It sounds to me like you're nearing the point when it would be a good idea to give SJS Cycles a call and ask their advice on configuration and accessories. No one knows better as they design, build, and service their bikes so they've seen it all, addressed every parts conflict and know what works the best and longest over all models sold. Though busy (especially now they are dealing with the demands of the virus and supply-chain problems), they're known for giving a good steer on which direction to go when outfitting their bikes for a specific purpose -- they know for a certainty which works with what.

Their recent brochures were structured around "recipes" -- bikes pre-configured in a variety of ways. I don't see that approach in the current brochures but if you go here...
https://www.thorncycles.co.uk/bikes
...and scroll down to the section devoted to the Nomad Mk3, you'll see five different configurations. I'd suggest picking one closest to your needs as a baseline, then giving SJS Cycles a ring to ask specifics and advice on belt drive, gearing, and wheel security options and what the cost might be if you deviate from the configurations shown. While there are proven, tried and true configurations, everyone's needs are different and they can help you identify and address those differences as you home in on a purchase.

Sometimes, people will buy one of these "spec bikes" and ride it for awhile to better assess their own needs going forward, then change or add components as their needs are defined.

Thorn's MegaBrochure/Touring Bike Bible does a good job of walking the reader and prospective buyer through the current choices and options available in frame fitting by preference and size, wheel/tire size, handlebar type, brakes, forks, saddles, and so on. Typically, if you wish to have Thorn build your bike with parts not listed in this MegaBrochure, then you can purchase them separately/additionally from SJS Cycles' available inventory, have them installed at time of build, and the original spec parts will be bagged with the bike. Alternatively, you can source your own parts from any vendor and install/swap them yourself after you receive your bike or have your local bike shop do so for you. Some members prefer to purchase only a Thorn frame and swap parts from a bike they already own or build it up using parts they purchase from SJS Cycles or elsewhere. If you go this route, keep in mind Thorn's superb warranty is only included on complete bikes built and sold by them.

This is the approach I took in 2011 with my Sherpa and in 2012 with my Nomad Mk2 and I also dove deep into the Forum archives using the search engine. As a result, I was very happy with the spec of each of my bikes on delivery and beyond.

Best,

Dan.

[ourclarioncall]

Ah, found where I had asked similar question

http://thorncyclesforum.co.uk/index.php?topic=14028.0

[ourclarioncall]

Thanks Dan

Yes, after an email to sjs about belt drive and Rohloff warranty he was keen for me to give him a call, so I said I would over the next 7 days.

Just printed off the Thorn bible etc tonight to help me nail stuff down on paper instead of it being scattered around my brain , forum posts and screenshots of important info.

On builds 5a and b - Nomad mk3 26”, it says .......

Waiting for a batch of 26” rim brake forks

Oh no, does this mean I won’t be able to get a 26” wheel nomad ?

From what I picked up I think the last batch was rejected or something and I think that was quite a while ago. Unless it’s just that the brochure has not been updated or maybe Covid had put everything on hold and they are still waiting . Hmm

I guess I’ll find out soon enough when I call

[Danneaux]

...Oh no, does this mean I won’t be able to get a 26” wheel nomad ?

The Covid-19 pandemic has disrupted bicycle supply chains worldwide, causing delays. A lot of bike shops as well as makers are temporarily short of essential stocks. It is possible you may have to wait to get your specific spec until a delayed shipment arrives.

It may be possible to reserve your choice in advance with a deposit. Robin can advise if this is still possible.

Best,

Dan.

[ourclarioncall]

Ah okay 👍

I am slightly tempted by 650b , but they only come with disc brakes . Il chew it over. The other option is a nomad 2 frame and fork , but it’s 620L or 620M, which I suspect might just be a touch on the big side. Il have to check my measurements again

[martinf]

I'd second Dan's advice about contacting Thorn/SJS for advice. I took over a year to work out what I wanted when buying my first Thorn (2010-2011). I thought I wanted a Nomad, but after communication with Andy Blance at Thorn he convinced me to get a Raven Tour instead as he thought it would suit my current and intended use better. I haven't regretted that.

Andy also strongly advised flat bars with bar-ends rather than drops. I was less sure about this, so I bought the flat handlebar he advised and fitted it to my old mountain bike and rode this for more than 1000 kms before deciding I wanted drops anyway. I finally ended up with shallow drops, which suit me well at the moment, and could quite easily go to flat bars or (more likely) "sit up and beg" style bars if I need to as I get older.

The consensus at SJS was fairly strongly against Chaingliders. I was also quite sceptical about a chaincase that just rides on the chain, so I bought one to fit on my old utility bike and tried it. I did some timed test rides over a roughly 25 km circuit before and after fitting, which convinced me that in my normal riding conditions there was negligible extra friction.

For the gearing I was already convinced I wanted a Rohloff hub gear rather than derailleurs, having used Sturmey-Archer S5/2 five speed hubs for most of my utility riding since the late 1970's.

For the choice of transmission I considered 4 possibilities:

- shaft drive. Not possible on a Thorn, but can be found. Advantage : no chain or belt to clean. Major disadvantage : significantly less efficient. Not a problem on a BMW motorbike with a big engine, but important with the limited power from my legs. I have ridden a shaft-drive bicycle for a short distance.

- belt drive. At the time, I couldn't see much advantage in a belt drive, in 2010 they were less common than now and there were still a few teething problems. And having brothers who used Mercedes vans with timing chains instead of belts I am convinced that a protected chain is at least as good as a belt as far as longevity is concerned. I don't think there is much difference in efficiency between the two systems if they are correctly set up. And a chain is much cheaper and easier to replace on tour if necessary.

- unprotected chain drive. What I had been using for over 40 years. Cheap, simple to replace, easy to find on tour (at least in Europe), but with the major disadvantage that the chain/chainring/sprockets/derailleurs pick up muck if used in wet or dirty conditions. Eliminating the derailleurs and multiple sprockets/chainrings by fitting a hub gear improves things significantly as the chain is higher and picks up less muck, so slightly less need to clean, and cleaning is much easier with only 1 chainring and sprocket and no little derailleur pulleys. There is probably a slight efficiency drop with a hub gear as compared to a clean, unworn derailleur system, but not enough to put me off. My experience over decades of running a hub gear utility bike and a 15-speed derailleur touring bike meant that I considered the hub gear bike to be actually more efficient if maintenance time and riding time are combined.

- chain drive with chaincase. Having ridden Dutch style hire bikes I wanted a chaincase, at least for my utility bike. But all the ones I had seen or tried had issues, they rubbed on part of the transmission and made a noise, were quite bulky, difficult to fit and dismantle (for example to change a worn tyre. Punctures can usually be repaired without removing the rear wheel). So I never got round to fitting one until reading the Chainglider posts by Andre Jute on this forum. After my tests on the utility bike, I decided that I would specify chain drive and Chainglider for my first Thorn, with the option of chucking the Chainglider away and reverting to unprotected chain drive if it didn't work out for me in touring conditions. A Chainglider is relatively cheap compared to a belt drive. In my experience it doesn't completely stop muck or water from getting at the chain, but it seems to me to be a pretty good compromise, reducing the need for chain maintenance and significantly extending the longevity of transmission parts, at least in my riding circumstances. Compared to other chain enclosures, with a little practice it is quick and easy to remove, for example to change a worn tyre.


Since 2010, there have been improvements in belt drive. But it is still more expensive (initially) than chain drive, and, in my opinion, less easy to set up and maintain if something does go wrong.   
 
And with the rise in popularity of electric bikes, there have also been improvments in unprotected chain drive, the KMC wide sprocket/chainring and chain combination is guaranteed for a minimum of 10,000 kms. I would have been tempted by this if it had been available 10 years ago.

[JohnR]

I've pedalled 2000 miles since putting a chainglider on my Mercury last October - details here http://thorncyclesforum.co.uk/index.php?topic=13973.0 . The two challenges were (i) finding a suitable chainring (Thorn's standard aluminium ring is too thick) and (ii) the need to cut a bit out of the rear section to provide clearance on the chainstay. My local roads get pretty filthy during the winter months and the chainglider has helped to protect the chain. However, as noted above, it doesn't keep out all muck - I think the main entry point is the loose fit around the rear sprocket. The other attraction of the chainglider is elimination of the risk of getting oily muck on the trousers. I've used a hacksaw to cut a couple of marks on the chainglider where the two parts fit together so I know the right setting for refitting after removal.

As for disc brakes: After getting my first bike with disc brakes I quickly realised that I valued the reliable stopping with no obvious disadvantages. Thorn make the point about needing stronger forks but offer the option of disc on rear and V brake on front (visible on some of the bikes at https://www.sjscycles.co.uk/new-used-cycles-frames ).

[Andre Jute]

Let me suggest something to you. I can't help but think that you're making a mistake by going at this process piecemeal, asking about this component and that component; that is why the Thorn bikes have suggested setups -- and, this is very important, they are tailored to your purpose with the bike and your desired/required posture on the bike. This is a design outlook commonly associated with Andy Blance, in my not so humble opinion the best bike designer working in Britain in the last twenty or more years, recently retired -- but the bikes Thorn sells are his designs and specifications, which start from fitting the bike properly to the cyclist. Without a proper fit, you're buying a lot of pain very expensively. You've come by planning or luck to a designer and vendor with a brilliant understanding of the gestalt of a proper bicycle, and you're subverting it by considering the pieces before the whole, which risks undermining the advantage you've gained by coming to the right place and people.

You've decided you want a touring bike, and it has to perform some other named functions; you presumably know your local bicycling topology; you know how you want sit on the bike or how your back will allow you to sit. Thorn has so many variants of their bikes that you can fine-tune your choice of bike to your desired posture a.k.a. the perfect fit. But you won't do that if you're concerned about your image on the bike. Generally speaking, I'd say that in the Thorn price range, you're best served by an attitude that says, "When you can understand a bike like my Thorn, I'll care about what you think of how I appear."

I share your preference for long wheelbases. My favourite bike for the last dozen years is a 29er over two metres long on which I make remarkable speed downhill on tiny country lanes because I've set it up for a safe margin of understeer; the local peloton frighten themselves poopless trying to keep up with a greybeard on a prewar priest's bike. I sit as upright as is possible without putting my spine in direct line with the bumps coming up the frame.

I'd suggest that you listen seriously to Robin Thorn's suggestion, and then ask him if a longer wheelbase can be adapted to the same posture on the bike. (I did it with a very wide Brooks saddle and North Road bars bringing the grips back to me without me leaning forward to reach the grips.) But you'd better be sure you're willing to pay some price for leaving behind the certainty of all that experience by actual tourers that go into the Thorn bikes.

In fact, while I'm trying to help you achieve your purpose as stated here, if it were me in your enviable position, I wouldn't try to outguess Andy Blance and Robin Thorn. I'd take the suggested bike and outfitting after ascertaining that the 100 days free trial still operates, ride the bike for 99 days, and then, if still enamoured of a longer wheelbase, give it back and buy the longer wheelbase instead, and start experimenting with handlebars, stems and saddles -- and with the much greater knowledge gained in the process -- in order to maintain the posture proven successful with the "correct" maximally fitted SWB bike on the new longer wheelbase by bringing the handlebar grips closer to me after adjusting the seat to put my feet on the pedals and knees over them to be the same as on the shorter wheelbase. It can be done -- my bikes are all set up to within a millimetre in three dimensions -- but it takes enough time to be a hobby in its own right and it can get pricey enough to give Dan the shivers, though I don't care as I think that entire cycling concept of getting every last inch of wear out of every component belongs to an age when a bicycle was a poor man's essential transport rather than a comfortable man's lifestyle accoutrement (good bikes are today obscenely expensive!). I have no hesitation in saying that experimenting for the dozen years before I got my perfect bike with other bikes of various wheelbases persuaded me that the extra cost of developing the long wheelbase bike to the singular zero-compromise perfect fit has been proven well worth it. But my best guess is that after a 100 days they'll have to pry the perfect-fitting bike from your cold dead fingers because you won't want to take the chance that anything else won't fit as well.

***
To return to the specifics of this particular thread, the Hebie Chainglider, once you know what transmission range you want the Rohloff to cover in its 14 gears (we generally work in gear inches here, e.g. 19-90 gear inches), you can determine which of the standard gear sets Thorn offers on their semi-custom bikes will suit both you and a Chainglider and choose that. In general, you want to choose the largest (most teeth) combination of sprocket and chainring that makes the right ratio, because larger chainrings and sprockets help chains to last longer, and last longer themselves. Note however that you can fit a Chainglider later -- no tools are required and it is extremely simple to snap on--, so don't waste time arguing the case with Mr Thorn, who clearly doesn't trust the thing (or perhaps its makers, who gave a member of this forum embarrassingly poor advice), despite the good experience a good number of his customers have had with it.

Good luck with your bike to be!

[WorldTourer]

I am convinced that a protected chain is at least as good as a belt as far as longevity is concerned.

I just don’t see how this is possible. Chains don't wear out because of contamination on the chain, the thing that a Chainglider protects against. They wear out because they stretch over time, and they start to wear down the chainring and cog.

A belt drive will give you a good 30,000 km of life, a statistic that has been proven now by numerous RTW and Alaska–Ushuaia expeditions. Even if you somehow managed to get that enormous distance out of a chain, surely you would then need to replace the chainring and cog by the end. With a Gates belt drive, on the other hand, you just pop the belt off your existing chainring and cog and just put a new belt on them (with the way things are now – earlier Gates systems required more frequent cog replacement).

[Danneaux]

Quote from: martinf on Today at 12:33:51 AM
I am convinced that a protected chain is at least as good as a belt as far as longevity is concerned.

I just don’t see how this is possible. Chains don't wear out because of contamination on the chain, the thing that a Chainglider protects against. They wear out because they stretch over time, and they start to wear down the chainring and cog.

Chains don't really stretch (like a rubber band); they elongate through wear of all their components, primarily the rollers and the pins they ride on. The tolerances increase as a result of wear coming from two sources:

1) friction from lack of lubrication (not just a dry chain but from oil failing to protect due to rain water washout)
...and...
2) contamination (dirt mixes with oil and makes a very efficient grinding paste).

A chain elongated through wear changes pitch; it is this pitch mismatch that wears down the chainring and cog.

If a chain is protected from environmental factors and can retain its lubrication, wear is greatly reduced. This is why timing chains can last so long on internal combustion engines, often handily exceeding that of timing belts. When I owned and operated my automobile repair shop in another life, it was common for chains to far outlast belts. Woe betide the sorry soul who exceeded the belt replacement interval on an engine with interference design. The eventual day when valves shook hands with pistons was never a good one.

Best,

Dan.

[WorldTourer]

Dan, what you say may be true in theory, but do we have much real-world support for it? Can you link to any accounts where a tourer has cycled 30,000 km on a single Chainglider-protected chain and, at the end, did not have to replace the cog and chainring as well?

[JohnR]

Although the belt might not wear out for 30,000km, you'll need to carry a spare belt in case of accidental damage(eg something gets caught in the teeth and makes a cut). Should that accident happen, then you'll be wanting a new spare. They aren't so easy to find (SJS only has some sizes in stock https://www.sjscycles.co.uk/chains/108t-1188mm-gates-carbon-drive-cdx-centertrack-belt-black/ ). With a chain it's only necessary to carry a couple of spare missing links although it's unusual for chains to break rather than wear out. For the cost of a belt you can buy several chains, a couple of spare sprockets and a spare chainring.

Another disadvantage of belts is, should you want to change the gearing, then there's the cost of the new belt in addition to the new chainwheel or sprocket. I've been there.