rear sproket and chain modification on the Agattu
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on the pro connect I was going to go for a 16 as the 8 speed hub has more range. On the agattu ive ordered an 18 and a 16 so I can see which works best
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No such thing as new knowledge, I'm just recycling what others have taught me. Talking of which, where is Flecc??
Paul
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It is still early days on my 45cm Pro Connect but on the subject of gearing thus far...
Haven't gone lower than 4th on my run to/from work, which does include a hill (not sure on the %, I used to go as low as 1st on the steepest bit on my old MTB (10 gears)).
On the flat mostly in 7th/8th.
On the downhill not doing a lot of pedaling - so would like the equivalent of 9th/10th.
Comfortable to ride on the flat without assist, doesn't feel heavy.
From the recent post (thanks stokepa31_mk2 I now have a better understanding on the effect of the change) looks like a reduction in sproket change might give me a few better options, but still at the getting used to it stage so will see how it over the first couple of weeks.
Haven't gone lower than 4th on my run to/from work, which does include a hill (not sure on the %, I used to go as low as 1st on the steepest bit on my old MTB (10 gears)).
On the flat mostly in 7th/8th.
On the downhill not doing a lot of pedaling - so would like the equivalent of 9th/10th.
Comfortable to ride on the flat without assist, doesn't feel heavy.
From the recent post (thanks stokepa31_mk2 I now have a better understanding on the effect of the change) looks like a reduction in sproket change might give me a few better options, but still at the getting used to it stage so will see how it over the first couple of weeks.
Im sure people would jump up and down (me included) if you could find time to add a couple of pictures of the Bike.
dont forget the 45 is a step through Bob so wont look like yours. Would love to see it nontheless
Regards
Paul
just found this on ctc which might be useful to anyone attempting the gear mod
....................................................................................................
Most hub-gears, including Shimano plus Sram-Sachs and most Sturmey-Archer, accept the same, standard, 3-spline pattern of sprocket. They are available with up to 22 teeth (1/8 chain) and Sram also makes a 24T×3/32, so it's easy to lower the gears on a hub-geared bike. The sprocket plus maybe a washer or two are held on by a spring-steel split-ring. Prise that ring out of its groove (with screwdrivers or whatever) and the sprocket simply slides off. Slide on another and snap the ring back.
But first you generally have to remove some part of the gear-change apparatus. In the case of Shimano they call this gubbins a “cassette joint”. It comes off easily too, when you know how. When you don't though …!
The necessary Service Instructions ought to be supplied with the bike. Failing that they can be downloaded from the web. Visit Shimano Europe Home and browse to Technical Service/Documents for the appropriate hub and shifter.
For those listening in black and white: first shift into gear No.1 and detach the cable by pulling the casing forward out of the "cassette joint bracket"; then sideways so the cable passes through the slit; then back toward the hub so the cable and it's anchor bolt can be lifted from the "cassette joint pulley". Learn this operation well – and its reverse – since it's what you'll often do to remove and replace the wheel.
Now to remove the cassette joint, rotate its fixing ring" 45° (1/8 turn) anticlockwise, then the bracket and pulley assembly simply lifts off the hub "driver". Also lift off the "driver cap", a dished washer, noting the direction of dish, and finally you are ready to get to work on that springy split-ring thing!
To replace the cassette joint on the hub, first don't forget the driver cap, then line up red dots on the pulley, the bracket and the hub. Follow that with the fixing ring, aligning yellow dots this time, on pulley and ring, before twisting the ring 45° clockwise to lock everything in place.
This process of cable and cassette joint removal is virtually the same for all Shimano hubgears with 4 or more speeds, but the joints themselves are not the same so don't mix them around – in some the pulley can be separated from bracket. A bit of cleaning may be needed to reveal the coloured dots!
....................................................................................................
Most hub-gears, including Shimano plus Sram-Sachs and most Sturmey-Archer, accept the same, standard, 3-spline pattern of sprocket. They are available with up to 22 teeth (1/8 chain) and Sram also makes a 24T×3/32, so it's easy to lower the gears on a hub-geared bike. The sprocket plus maybe a washer or two are held on by a spring-steel split-ring. Prise that ring out of its groove (with screwdrivers or whatever) and the sprocket simply slides off. Slide on another and snap the ring back.
But first you generally have to remove some part of the gear-change apparatus. In the case of Shimano they call this gubbins a “cassette joint”. It comes off easily too, when you know how. When you don't though …!
The necessary Service Instructions ought to be supplied with the bike. Failing that they can be downloaded from the web. Visit Shimano Europe Home and browse to Technical Service/Documents for the appropriate hub and shifter.
For those listening in black and white: first shift into gear No.1 and detach the cable by pulling the casing forward out of the "cassette joint bracket"; then sideways so the cable passes through the slit; then back toward the hub so the cable and it's anchor bolt can be lifted from the "cassette joint pulley". Learn this operation well – and its reverse – since it's what you'll often do to remove and replace the wheel.
Now to remove the cassette joint, rotate its fixing ring" 45° (1/8 turn) anticlockwise, then the bracket and pulley assembly simply lifts off the hub "driver". Also lift off the "driver cap", a dished washer, noting the direction of dish, and finally you are ready to get to work on that springy split-ring thing!
To replace the cassette joint on the hub, first don't forget the driver cap, then line up red dots on the pulley, the bracket and the hub. Follow that with the fixing ring, aligning yellow dots this time, on pulley and ring, before twisting the ring 45° clockwise to lock everything in place.
This process of cable and cassette joint removal is virtually the same for all Shimano hubgears with 4 or more speeds, but the joints themselves are not the same so don't mix them around – in some the pulley can be separated from bracket. A bit of cleaning may be needed to reveal the coloured dots!
I have always felt my Agattu to be undergeared, as I am used to gearing of 48/36/24 with a 11-34 rear sprocket on my mountain bike. I bought a smaller replacement sprocket from 50cycles when I bought my Agattu and swapped it back and forth a few times with the original sprocket to try the difference. I understand the argument that reducing the size of the rear sprocket will increase the assisted speed but reduce the range, but I feel this may not be the full picture.
For arguments sake, say that I reduce the rear sprocket on my Agattu, and by doing so I increase the overall gear ratio so that what was previously the ratio of 7th gear is now achieved in 6th gear. Am I right in thinking that with the new setup, if I never cycle higher than 6th gear, the range would not be affected? If this is true, then surely I have the choice of normal range if I stay in 6th gear or higher top speed if I use 7th gear?
For arguments sake, say that I reduce the rear sprocket on my Agattu, and by doing so I increase the overall gear ratio so that what was previously the ratio of 7th gear is now achieved in 6th gear. Am I right in thinking that with the new setup, if I never cycle higher than 6th gear, the range would not be affected? If this is true, then surely I have the choice of normal range if I stay in 6th gear or higher top speed if I use 7th gear?
Hmmmm....not quite. They way I understand it is that by increasing the gearing by using a smaller rear sprocket you also increase the assist speed in all gears.This means that there is no advantage in not going above 6 gear with the sprocket change and thinking that range will be unaffected because the motor will still be assisting you to a higher speed in gears 1 - 6 and therefore the battery will be depleted more quickly just as before. I think that makes sense
If Flecc sees this I am sure he will tell me if I am talking out of my behind or if this makes sense.
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Yes of course, you would just be regarding the seventh gear as an overdrive in that case. I'd also be happy with that, but many also change the sprocket because they don't like higher pedal cadences and feel that the 65 cadence at 15 mph is too fast, so for them that would be self defeating.
But for those of us who don't mind cadences of 65 to 90 it's a good way of achieving the choice of modes, speed or economy, just so long as enough of a low gear range was left.
.
Just saw the post by Citrus. In fact the 6th gear would be the same as the old 7th, because a smaller sprocket of the right size would potentially slow the pedalling by the same amount as the lower gear inside the hub increased it, so the two self cancel.
.
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Just answered Citrus above. The motor doesn't know the rear sprocket size, it senses it's output sprocket's speed, so therefore the chain speed and rear sprocket and hub relationship. Read through the relevant page on my Lafree/Kalkhoff website and the motor unit operation is fully explained there, mainly in the second half of the page:
Panasonic unit mechanical operation
For a description of how the software works, see my article in the technical section:
Panasonic unit software operation
.
,
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Previous posts on this thread:
OK. Im sorry to be a bit thick tonight (long day, long ride home ) but is your last post agreeing with Citrus's view that the range will be reduced no matter what or are you agreeing that the 'overdrive' description is a valid way to view the modified Agattu transmission?
Hmmmm....not quite. They way I understand it is that by increasing the gearing by using a smaller rear sprocket you also increase the assist speed in all gears.This means that there is no advantage in not going above 6 gear with the sprocket change and thinking that range will be unaffected because the motor will still be assisting you to a higher speed in gears 1 - 6 and therefore the battery will be depleted more quickly just as before. I think that makes sense
OK. Im sorry to be a bit thick tonight (long day, long ride home
) but is your last post agreeing with Citrus's view that the range will be reduced no matter what or are you agreeing that the 'overdrive' description is a valid way to view the modified Agattu transmission?
No problem.
I'm agreeing that the overdrive way is a valid alternative way to look at having a smaller rear sprocket, and explaining to Citrus why the new 6th and the old 7th gears are the same thing if the sprocket is chosen to shift the gearing by the right amount.
Therefore an overdrive gear has been added.
.
I'm agreeing that the overdrive way is a valid alternative way to look at having a smaller rear sprocket, and explaining to Citrus why the new 6th and the old 7th gears are the same thing if the sprocket is chosen to shift the gearing by the right amount.
Therefore an overdrive gear has been added.
.
Thanks for that. Very helpful.
I think on that basis I think I will probably go for the smaller sprocket from now on. There seems to be little advantage to pedalling the standard Agattu at more than 16-17 mph due to the high cadence required. My average commute on the Agattu is a very easy 60 minutes and on my mountain bike, 45 harder minutes due to the higher average speeds (with no assist other than lard downhill ). I'd like to try and even them out a bit.
I think on that basis I think I will probably go for the smaller sprocket from now on. There seems to be little advantage to pedalling the standard Agattu at more than 16-17 mph due to the high cadence required. My average commute on the Agattu is a very easy 60 minutes and on my mountain bike, 45 harder minutes due to the higher average speeds (with no assist other than lard downhill
). I'd like to try and even them out a bit.Related Articles
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