Thorn 38T 104BCD 4 arm front chain ring with Hebie Chainglider

[Captain Bubble]

Hi, Is anyone successfully using the above combination? Do the chain ring bolts of this 38T chain ring foul the chainglider?
Many thanks.

[WorldTourer]

I was unable to use this chain ring and the Thorn cranks with a Chainglider . Everything was just a bit too thick for the Chainglider. Instead, I ended up using the Surly 38T steel chain ring, which is thinner, but that also necessitated buying new cranks, too.

(Note that in the end, I was very dissatisfied with the Chainglider and threw it away in the middle of a long tour, and I regret the whole effort of installing it and finding a compatible chainring and cranks.)

[JohnR]

The Thorn chainring is too thick for a Chainglider. I'm using a 42T one of these steel chainrings https://www.sourcebmx.com/products/jet-bmx-4-bolt-race-chainring?variant=31801814712431&currency=gbp with a Chainglider and, so far, am happy. More here with some photos http://thorncyclesforum.co.uk/index.php?topic=13973.0 .

[Captain Bubble]

Thank you both for your replies. A little context for you. I already have a chainglider working well on a 42T Thorn chainring with 5 arm 140BCD crank (FSA). I just want to lower the gearing. I bought a Thorn 38T 5 arm 130 BCD chain ring already but hastily over looked the fact that because it's a smaller ring then the chain ring bolts are correspondingly nearer the edge on a 130 BCD 5 arm crank. The chain ring bolts sit proud of the surface of the chain ring itself and will foul the chain glider case as the chain ring rotates inside.

Therefore I am hoping that with a 4 arm 104cm crank the chain ring bolts won't be so near the edge of the chain ring as the crank is smaller allowing me to use a chainglider without it fouling the chain ring bolts. My question is specific to this. Not interested in anything else.

@WorldTourer - So you are saying you have tried this chain ring size albeit a Surly chain ring with a 104mm BCD 4 arm crank and your chainglider before you threw it away did not make contact with the chain ring bolts? On my 42T chain ring I have measured the gap needed from the tip of the ring teeth to the inner edge of the glider and I guess about 15-16mm clearance is needed. Any less and the glider will foul the chainring bolts.

I have already bought a 38T front section Chainglider and Thorn 104 BCD 4 arm crank from SJS. I just don't want to lay out another £45 for the chain ring if it is not going to work. If you could just confirm or even post a pic of your 38T chain ring and crank this would be helpful.

I've emailed SJS but they have been unable to help so far, so I ask here.

Initially I had a love hate relationship with my chainglider as it did rub at the start I guess because of the slightly thicker Thorn chain ring, but over the last few years it's been less fraught and the cover now does what I had hoped it would do right from the start keep the chain clean and totally silent. It's quite a good fit now, few gaps. I think a lot of the problems centre around fitting it properly. One you have done this a few times it gets easier. Not saying you didn't but I now wouldn't ride without one on my bike. It seems to massively increase the life of the chain plus of course shield you from getting crud and lube on your hands, clothes and anything else. How come you threw yours away?

@JohnR Thank you for your suggestion. Your link to the BMX chain ring is useful quite apart from the fact that it is a fraction of the price of a Thorn and definitely a Surly chain ring. I note from your installation of one of these BMX rings you had to make some mods and also had to adjust the chain line. I was under the impression the chain line for the Rohloff with the std splined carrier was 54mm?

Thanks again.

[WorldTourer]

When I switched to the Surly chainring to get something narrow enough for the Chainglider, I also had to switch the cranks: Surly chainrings are 5-arm.

I threw my Chainglider away because in the dusty regions I was traveling through, it failed to actually keep my chain clean, and it required constant adjustment. The only good thing it did was keep oil off my trouser leg. However, I prefer going without the Chainglider for these few months until I convert the bike to a belt setup, which offers vastly longer life than a chain, Chainglider or no.

[Captain Bubble]

When I switched to the Surly chainring to get something narrow enough for the Chainglider, I also had to switch the cranks: Surly chainrings are 5-arm.

I threw my Chainglider away because in the dusty regions I was traveling through, it failed to actually keep my chain clean, and it required constant adjustment. The only good thing it did was keep oil off my trouser leg. However, I prefer going without the Chainglider for these few months until I convert the bike to a belt setup, which offers vastly longer life than a chain, Chainglider or no.

Oh, Surly chain rings 5 arm and 130 bcd? If so then with a 38T chain ring, the chain ring bolts will foul the chain glider. So Surly chain rings are a no go. I know as I have this set up here at home although not fitted. I realised this just before I was about put the first chain ring bolt in when attaching the ring to the crank. I guess the Thorn chain rings are thicker as they are 7075 aluminium and not steel and need the extra thickness to maintain rigidity, but I guess they are lighter.

Maybe I shall just have to fit a 17T rear cog as my bike currently has 16Tx42T. It would be a lot cheaper. In fact I shall do this as lower the gearing by using a smaller front ring and retaining use of the Chainglider is becoming too complicated.

It would interesting to see if any cover whether partial or full could be found or indeed manufactured for a belt drive installation? Maybe with the increasing popularity of Ebikes (wretched things) some one has made a cover to keep the belt clean as many of them use Gates belts. Car cam belts are enclosed as well. Why are there no covers available for bicycles with belt installations?

Thanks again.

[WorldTourer]

It would interesting to see if any cover whether partial or full could be found or indeed manufactured for a belt drive installation?  Why are there no covers available for bicycles with belt installations?

Belts don't need any lubrication on them. That means that they don't attract dirt. They are no more dirty than e.g. the bike's rack or the frame, and therefore they don't need to be covered. While in very dusty terrain one might want to clean them just for the sake or it or to prevent noise, that can be done just by spraying some water over them.

[Captain Bubble]

It would interesting to see if any cover whether partial or full could be found or indeed manufactured for a belt drive installation?  Why are there no covers available for bicycles with belt installations?

Belts don't need any lubrication on them. That means that they don't attract dirt. They are no more dirty than e.g. the bike's rack or the frame, and therefore they don't need to be covered. While in very dusty terrain one might want to clean them just for the sake or it or to prevent noise, that can be done just by spraying some water over them.

This may be a little simplistic. The belt is a moving component unlike a rack or the bike's frame. It will run at it's best and most efficiently when clean and free of debris. Yes it will still turn if dirty but just like a chain it's performance can be compromised by contaminants/debris. As you allude it's  better than a chain in terms of lower and easier maintenance, but still not perfect. I suspect you still wouldn't want to get it caked in mud. You'd still have to find a water source and hopefully a hose to clean it. It would be better to minimise dirt getting onto it in the first place just like a chain. Hence the Hebie Chainglider. It will only be time before some one comes up with a belt cover whether Gates, Hebie or some one else. There is definitely a gap in the market at the moment.

[martinf]

Hi, Is anyone successfully using the above combination? Do the chain ring bolts of this 38T chain ring foul the chainglider?
Many thanks.

I use 110BCD 5-arm cranks with 38T chainrings (on several bikes) and the  chain ring bolts don't foul the Chainglider.

I haven't tried them, but 104 BCD is smaller than 110, so 104BCD 4 arm cranks should be OK.

[martinf]

(Note that in the end, I was very dissatisfied with the Chainglider and threw it away in the middle of a long tour, and I regret the whole effort of installing it and finding a compatible chainring and cranks.)

Another "advantage" of the Chainglider, it is very easy to revert to a standard setup if you don't like it!

[WorldTourer]

This may be a little simplistic. The belt is a moving component unlike a rack or the bike's frame. It will run at it's best and most efficiently when clean and free of debris.

Have you ever actually cycled for long distances with tourers running a belt? I have, including a complete crossing of the sandy Sahara on the Europe–West Africa route, and I saw that dust getting on the belt was a total non-issue. They had no difficult cycling normally and moving just as fast (or faster) as me with a chain, and they only cleaned their belts once only every several days or weeks. No, I don’t think that covers will be seen as necessary.

Sure, one needs a water source to clean a belt, but that's not a big deal considering that you also need a water source to keep yourself alive and hydrated.

[Andre Jute]

The greatest advantage of a Chainglider, after eliminating attention to the chain, is that its efficiency over any day, and for the entire life of the chain inside it, as I have proven with my experiment of running the chain on the factory lube for its entire life, is a constant. That is not true of an open chain, or indeed a Gates belt the efficiency of which between cleanings can only decline. I fail to believe that a dirty Gates belt is as efficient as a clean one.

As for failing to make a properly sized Chainglider work with the bike, the fellow who threw away a Chainglider should have consulted here before he threw it away. There may have been something I missed, but the sum of experience of trouble with Chainglider here amounts to:

1. A mismatched Chainglider leaving chainring teeth exposed. Obviously that won't work.

2. Chaingliders fitted with insufficient attention to the optimum positioning of the chain runners and the Rohloff rear section causing perceived drag. Solved by a few minutes of moving the parts, which are stepped, in and out first on the top and then on the bottom, until it runs silently and without drag. We don't have even one report that this simple remedy failed to deliver the Chainglider's promise.

3. Far more serious than either of the easily solved problems above, on some bikes the frame interferes with the correct positioning of the Chainglider. Nobody liked paint rubbed off an expensive bike. A solution touted here by some handy cyclists is simply to take a pocket knife or a file or a small surfers to the Chainglider and carefully remove only enough material to provide clearance.

4. Hebie not making the Chainglider in all the configurations popular with tourers. But even this has a workable solution, as John Saxby has demonstrated by tidy surgery on the part of the Chainglider covering the rear of the chainring to achieve a ratio not refreshed by Hebie.

***
I must say that, even if there is a cover for the Gates Belt that will keep it clean for life, and therefore entirely obviate any necessity for cleaning or other service, I would still want several questions answered before I splash out several times the price of a crankset and a sprocket and a chain to change my bike's transmission.

1. What is the actual expected lifespan of the Gates Drive with the cover? The cover is important for keeping your street clothes clean if you cycle in them. Last I heard, Gates Corporation was claiming no more than the mileage per chain under a Chainglider expected by several posters here. The Chainglider trebled the distance I got out of a chain, but I could have done better by not throwing off chains at two-thirds advised elongation, by riding them to the full advised elongation.

2. What is the efficiency of a Gates Drive in comparison with a Chainglider-covered chain?

Longrange tourers will no doubt have further questions.

***
If satisfactory answers are forthcoming, I might reconsider the cost of a Gates Drive conversion simply so as not to get my hands dirty when I change a chain worn out inside a Chainglider.

Or I might just invest a tenner in a big box of plastic gloves and a pot of barrier cream.

[JohnR]

Therefore I am hoping that with a 4 arm 104cm crank the chain ring bolts won't be so near the edge of the chain ring as the crank is smaller allowing me to use a chainglider without it fouling the chain ring bolts. My question is specific to this. Not interested in anything else.

@WorldTourer - So you are saying you have tried this chain ring size albeit a Surly chain ring with a 104mm BCD 4 arm crank and your chainglider before you threw it away did not make contact with the chain ring bolts? On my 42T chain ring I have measured the gap needed from the tip of the ring teeth to the inner edge of the glider and I guess about 15-16mm clearance is needed. Any less and the glider will foul the chainring bolts.

I have already bought a 38T front section Chainglider and Thorn 104 BCD 4 arm crank from SJS. I just don't want to lay out another £45 for the chain ring if it is not going to work. If you could just confirm or even post a pic of your 38T chain ring and crank this would be helpful.

@JohnR Thank you for your suggestion. Your link to the BMX chain ring is useful quite apart from the fact that it is a fraction of the price of a Thorn and definitely a Surly chain ring. I note from your installation of one of these BMX rings you had to make some mods and also had to adjust the chain line. I was under the impression the chain line for the Rohloff with the std splined carrier was 54mm?

Thanks again.

Here's a photo of a 38T chainring. I reckon you've got plenty of room but judge for yourself.

Yes, I had to get to work with a file to get my 42T steel chainring to fit comfortably on the arms - perhaps that's the side-effect of an attractive price tag. I needed to move the eccentric bottom bracket across slightly to compensate for the steel chainring being thinner than Thorn's aluminium chainring.

As for the merits of belt vs chain in Chainglider I can see that the belt could be better in dusty conditions but that's getting off-topic for this particular thread.

[WorldTourer]

Andre, you react strongly to someone criticizing the Chainglider, but considering that SJS doesn't recommend the Chainglider, then on this particular forum my position is a pretty mainstream one.

In my case, in very dusty/sandy and windy environments, the Chainglider was simply unable to prevent grit from entering. If that dust gets everyone else on your body and even inside of your handlebar bag, then it is no surprise it makes it through the opening around the cog, too. That means that every few days you have to clean the chain anyway, and that means having to reassemble the Chainglider and go through the hassle of adjusting it again.

As for "the cover is important for keeping your street clothes clean if you cycle in them", street clothes don’t really matter for touring, do they? I would be satisfied just to keep from getting oil on the expensive Fjällräven expedition trousers that I cycle in, and indeed a belt doesn’t stain clothing that way even when uncovered.

Belt drives have now been used on multiple Alaska–Ushuaia tours and Europe–West Africa–Cape Town tours, and the claim of 30,000 km on a belt is generally seen as reliable.

[Andre Jute]

Andre, you react strongly to someone criticizing the Chainglider, but considering that SJS doesn't recommend the Chainglider, then on this particular forum my position is a pretty mainstream one.

In my case, in very dusty/sandy and windy environments, the Chainglider was simply unable to prevent grit from entering. If that dust gets everyone else on your body and even inside of your handlebar bag, then it is no surprise it makes it through the opening around the cog, too. That means that every few days you have to clean the chain anyway, and that means having to reassemble the Chainglider and go through the hassle of adjusting it again.

As for "the cover is important for keeping your street clothes clean if you cycle in them", street clothes don’t really matter for touring, do they? I would be satisfied just to keep from getting oil on the expensive Fjällräven expedition trousers that I cycle in, and indeed a belt doesn’t stain clothing that way even when uncovered.

Belt drives have now been used on multiple Alaska–Ushuaia tours and Europe–West Africa–Cape Town tours, and the claim of 30,000 km on a belt is generally seen as reliable.

Nah, I do pointed argument for a living. When I "react strongly", you'll notice a difference. Anyhow, as we used to say when I lived in Australia, you aren't backward in coming forward for your own opinion.

All that said, I have no sentimental attachment to the Chainglider. If the Gates Drive offers me one less pair of oily hands per year, with no other disadvantage except the cost, I'd fit one in a flash. I said as much in the post we're discussing: "If satisfactory answers are forthcoming, I might reconsider the cost of a Gates Drive conversion simply so as not to get my hands dirty when I change a chain worn out inside a Chainglider." You'll also find, in an exchange of posts I had with Dan several years ago, that I mentioned that there was a distinct possibility that the playa dust on his annual desert tour would enter the Chainglider and cause more trouble than it is worth, perhaps even set in a solid concrete around his chain; I grew up in an African desert, so I'm sensitive and receptive to the dust argument.

You should have started with the 30,000km belt lifespan, which you include in your answer to me, and then this thread would have proceeded in a different direction.

Don't forget to let us know how the Gates belt does on your next tour. Good luck.