What is the lowest gear inch possible on a trike?

[Tigerbiten]

Just remember if you're building a back wheel, the back forks of an ICE trike are not symmetrical.
The righthand dropout is further from the centerline than the lefthand one.
This is so a cassette hub can be built with no dish for maximum strength.

[[XAP]Bob]

hence the long discussions - and the recommendation of PC

[Geoff.D]

hence the long discussions - and the recommendation of PC

As a result, I'm pretty sure that Practical Cycles are all geared up (pardon the pun) for this modification to the back end of an ICE, as Bob suggested earlier. For myself, I'm quite happy to recommend their work.

[[XAP]Bob]

And I'll happily recommend their service. They were quite happy to redish the wheel (and pay for postage both ways), and equally happy for me to have an lbs do the work at their cost...

The error was actually from SA, not PC.

[Trikeyohreilly]

Thanks you for all the ideas and information. Lots off food for thought.

I had never heard of the Mountain Tamer before which I think is the option I'm going to persue first. I'm going to put it on my other trike that has a 20" rear wheel though the beauty of this option is that it's transferable between bikes. I think it will give me a range of 8.8" to 64.5" run as a triple. Low top end but having worked out my cruising gear last year was 68.7" it's not too far off. The 26" wheel was just not getting low enough.

If I can afford it later an SA hub would be great. Added to the mountain tamer it would give 6.6" to 86" still too low at the top end for many but ample for me.

I also had my fears of slippage and lost traction allayed. I had been wondering about that. Thank you.

One bad point did come up though, I didn't know ICE's rear ends were off center. So the 26" wheel I already had and was planing to use won't fit properly. Still a good excuse to order an SA hub. 9.2" to 119.7" is possible that way with a 26" wheel.

Thank you all again. Ed

[[XAP]Bob]

I will just need redishing to fit - the offset isn't large, you might get away without new spokes even.

Basically the hub flanges for a normal wheel will end up centred around the rim, which is unusual for a cycle (but due to the lateral load on a trike wheel is a good thing).
It does mean that a single speed / internal geared hub will have negative dish - which is odd

[hercule]

re front derailleur mods for the Mountain Tamer... I found this page after posting:

http://abundantadventures.com/mtfaq/frontderail/fr.derail.mods.html

I don't have a need for lower gears (yet) on my QNT but my upright bike riding is mostly done on a Moulton and this article gave some useful food for thought on running a 39 - 52 - 62T triple - the mods I've tried before haven't been very successful and generally I have been limited on the size of the big ring as a result. Extending the cage might just work.

[manybikes]

I had a look at the Mountain Tamer page - going a little deeper into it. It seems that many rings sizes are now unobtainable (unless I've misinterpreted it). Although it looks interesting could it be you would be back to finding it difficult to maintain if rings are hard to get? The point about the Capreo cassette is well made - I could find a replacement of existing configuration ONLY from ICE and its not cheap!

[[XAP]Bob]

hence I got the cs-rk3 when the capreo was due for replacement, made the sting a bit less...

[Trikeyohreilly]

[quote="manybikes"]I had a look at the Mountain Tamer page - going a little deeper into it. It seems that many rings sizes are now unobtainable (unless I've misinterpreted it). Although it looks interesting could it be you would be back to finding it difficult to maintain if rings are hard to get? ![/quote

I've been down a similar thought process. He didn't want to sell me more than two of them also, meaning too few in the spares box for my liking.

Following some help from Freeflow I've identified that I already had a 58mm BCD c rankset in my spares box which allows me to fit a 20 tooth inner ring. These are readily available and as cheap as £11 at Spa cycles (just arrived by courier as I'm writing this post). Seeing as Mountain Tamer have sold out of the 17 tooth leaving 18 as the smallest he 20 tooth option is a lot cheaper, fairly close and more sustainable.

To get lower still I'm focusing on the SA hub next, then hopefully in the future a double ringed Mountain Drive.

Cheers. Ed

[Tigerbiten]

To get lower still I'm focusing on the SA hub next, then hopefully in the future a double ringed Mountain Drive.

Cheers. Ed

I looked at the Mountain Drive for my setup, but the High Speed Drive worked out better for me.
I could have gone 56/13 with the Mountain Drive (9"-118") which would have given almost the same range as the 30/16 on the High Speed Drive (9.8"-128") which I picked.
The reason I went for the High Speed Drive over the Mountain Drive was because of where the drag caused by the extra set of planetary gears was.
With the MD it's at the bottom end, so you'd hill climb with the extra drag but high speeds are easier.
With the HSD it's at the top end, so you'd hill climb with no extra drag and only get the extra drag on the downhill runs where it's not that important.

With the 53-38 chainrings and the 21 sprocket which I use now, I can now go from 1.5 mph in first up to 21 mph in 17th gear in the normal range with no extra drag which covers 90% of my cycling.
It's only above 21 mph do I engage the overdrive for the last 7 gears which can take me to around 50 mph downhill.

[Trikeyohreilly]

That makes a lot of sense. I can see why you did it that way around. When I have saved enough I think I'll have to have the drag at the low end though. It would only be worth the cash to me to get right down to sub five gear inches or there abouts. When the time comes I'll play with the gear calculator again but guess I'll have no choice. Hopefully the drag is not too bad.

Thanks. Ed

[[XAP]Bob]

There is a thread looking at 42 tooth sprockets in the bikes and bits forum.

22 tooth chainring to a 42 sprocket on a csrk3 might be out of spec....

ah, I see it's your thread

[Tigerbiten]

There is a thread looking at 42 tooth sprockets in the bikes and bits forum.

22 tooth chainring to a 42 sprocket on a csrk3 might be out of spec....

ah, I see it's your thread

But remember that on a trike there is no minimum speed unlike a bike.
So by dropping your speed right down, you also drop the torque through the hub right down.
That's one of the reasons I get away with a 9.5" first gear on my Rohloff.

[[XAP]Bob]

True, but the torque is related to the tension on the chain multiplied by the sprocket diameter (proportional to tooth count)

42 is 50% more than their testing (I suspect it still leaves a wide safety margin though)