Giant Lafree, will a 41t chainring fit?

[Tarik Berkhof]

I plan on trying to fit a 41tooth chainring on my Lafree instead of the 37t that's currently installed, has anyone ever tried this and will it fit?

 

[hech]

Evening Tarik and welcome to da forum. The venerable Flecc, our esteemed leader is the world authority on the Giant Lafree and will know all answers to everything you might wish to know.
Just as long as your bcd measurements are agreeable, sounds like a thoroughly good idea to me.

 

[mountainsport]

Evening Tarik and welcome to da forum. The venerable Flecc, our esteemed leader is the world authority on the Giant Lafree and will know all answers to everything you might wish to know.
Just as long as your bcd measurements are agreeable, sounds like a thoroughly good idea to me.

Hi hech,

It's a jolly good idea to me too,but why is flecc our true leader fast asleep right now counting spokes? And where is his spokesman to answer all important Giant Lafree questions?

Mountainsport.

 

[Cyclezee]

Hi Tarik,

As the LaFree has a one piece chainwheel that fits on a splined shaft, I doubt if there is an alternative to the standard without some engineering unless the chainwheel from the later Panasonic motor as used Kalkhoff etc. is compatible?

Why would you want to do this?

To alter the gearing, it is relatively simple to change to different size drive sprocket.

The following will take you to Flecc's LaFree website lafree

 

[tillson]

I'm also wondering why you would want to increase the size of the chain wheel. Doing this will make no difference to the assist cut off speed and will effectively decrease the pedal cadence for a given road speed. It might be easier to alter the size of the rear sprocket in order to achieve your goal.

 

[Tarik Berkhof]

Hi Tarik,

As the LaFree has a one piece chainwheel that fits on a splined shaft, I doubt if there is an alternative to the standard without some engineering unless the chainwheel from the later Panasonic motor as used Kalkhoff etc. is compatible?

Why would you want to do this?

To alter the gearing, it is relatively simple to change to different size drive sprocket.

The following will take you to Flecc's LaFree website lafree

The 41t chainring from the later panasonic model should fit the socket yes.

The reason why i wanted to do it was because i thought the -speed sensor magnets- inside the motor where fitted on the chainring crank(sorry dont know the proper word in english)thus increasing speed because the sensor would measure less rotation.
However i made an interpretation error, when looking at motorunit1 you can clearly see that the sensor is on the motor crank and not on the chainring crank meaning my deduction was simply put wrong.

So changing the chainring to 41t would only decrease the cadence at wich the motor would give support, wich would be utterly useless since the cadence is already low. On the brightside this actually means i can do something unexpected: increase cadence support by putting on a 37> chainring(37 is standard). 35-tooth Front Chain Ring would give the lafree a cadence of a little over 41, which is most likely unnoticeable in the real world.

My last option (i already changed the rear sprocket to 13 teeth) seems to be drilling out the magnet's in the motor's speed sensor but i have not been able to found any source that it has been done succesfully. The only information i can find regarding this is on flecc's website "This might not meet the approval of tweakers though! On the old unit, it was possible that drilling out every other magnet would double the 9.4 mph first power phase down point and double the 15 mph motor power cut-off. Illegal and very naughty of course!".
On the other hand, i do have a spare motor available for testing (bought 2 broken lafree's and fixed 1) so i could try it anyway, but id like to save the spare motor in case of emergency.

So does anyone have any information that would lead me to my goal? (is my goal clear for that matter? => increasing lafree speed by drilling out hall magnets) Would be much appreciated.

ps. Sorry for the typo's and grammar mistakes, im still learning english .

pps: If you're wondering why i want to do this: it's simply because i love engineering/modding/tweaking

ppps: If you're wondering how i fit a flat 13 tooth sprocket, dont. It's a horrible combination of 2 flat sprockets, a circlip, a special circlip and ducktape . Not to mention the case i had to modify.

 

[flecc]

Sorry I wasn't around last night. I haven't tried changing between the two chainwheels, but I'm practically certain the spline dimensions are identical. However. little point as others have mentioned, there being other ways of approaching what you want to achieve.

I can't guarantee that knocking out every other magnet on the gearwheel will enable the cut off speed to be doubled, but it should do. The only thing that could prevent it is a software override signalled from the torque sensor, but that is highly unlikely.

 

[Martin@e-bikeshop]

Hello Tarik,

I have tried fitting a 41t Chain ring on a Lafree before.

The splines are the same so it will go on the axle, however a 41t is just slightly too big to fit within the chain guard. It rubs on the chain guard too extensively to just bend the brackets out.

So you could do it but you may have to retro fit a bigger chain guard, which could spoil the overall look of the bike.

On a side note, when I changed the front sprocket on a customers recently, the original sprocket was a little thicker than the new later Panasonic one, there-fore I fitted a very small shim behind the sprocket and then applied the cir-clip to hold it in place, without the small shim; the sprocket did wobble on the axle. The shim resolves this (Shim approx 2mm thick)

May I add, we will soon be stocking a dongle to adjust the bikes cut off speed a bit like the Bosch dongle. This is in the making and should be expected for the Panasonic unit soon.

The bosch dongle allows the cut off top be extended to 50kph.. Should be a popular upgrade

For 'Off road use only' of course!

Regards

Martin

 

[tillson]

May I add, we will soon be stocking a dongle to adjust the bikes cut off speed a bit like the Bosch dongle. This is in the making and should be expected for the Panasonic unit soon.

Which Panasonic unit is the dongle for? Is it the older version used on the Lafree, the standard 24 Volt version used on the Kalkhoffs from about 2007 onwards, the S Class 24 Volt version or the latest 36 Volt Version? Just curious.

 

[Martin@e-bikeshop]

Which Panasonic unit is the dongle for? Is it the older version used on the Lafree, the standard 24 Volt version used on the Kalkhoffs from about 2007 onwards, the S Class 24 Volt version or the latest 36 Volt Version? Just curious.

Hi Tillson,

I will check with the manufacturers and let you know as soon as I know.
As both the old and new units operate in a similar way; but the newer one uses pulse rate of the hall sensor to judge speed. I would imagine the manufacturer will retail a different dongle for each. I should imagine they will be producing this just for the 24v version but like I say I will confirm all of this when I know from the manufacturer.

Regards
Martin

 

[flecc]

On a side note, when I changed the front sprocket on a customers recently, the original sprocket was a little thicker than the new later Panasonic one, there-fore I fitted a very small shim behind the sprocket and then applied the cir-clip to hold it in place, without the small shim; the sprocket did wobble on the axle. The shim resolves this (Shim approx 2mm thick)

The reason for this Martin is that the old unit only had sprockets for 1/8" chain (single speed and hub gear), the later unit sprockets are thinner to include provision for 3/32" derailleur chain.

Let me know the outcome on the dongle and I'll publicise it with you as the source for supply on my Panasonic support website
.

 

[Martin@e-bikeshop]

Tarik,

If you did want to 'play'
I have a 41t sprocket here, £15 delivered 1st class. Let me know if this of any use?..

Regards
Martin

 

[Martin@e-bikeshop]

The reason for this Martin is that the old unit only had sprockets for 1/8" chain (single speed and hub gear), the later unit sprockets are thinner to include provision for 3/32" derailleur chain.

Let me know the outcome on the dongle and I'll publicise it with you as the source for supply on my Panasonic support website
.

Thanks Flecc..
The sprocket sizing all makes sense now
I will let you know when I have more info. I can also let you know when they will be ready for sale..

Best Regards
Martin

 

[Martin@e-bikeshop]

Which Panasonic unit is the dongle for? Is it the older version used on the Lafree, the standard 24 Volt version used on the Kalkhoffs from about 2007 onwards, the S Class 24 Volt version or the latest 36 Volt Version? Just curious.

Tillson,

Just spoke with the manufacturer who can confirm that the new dongles are being produced for the latest 36v version.

That said there is the possibility of getting some 26v ones made up, I get on well with the manufacturer and they could make some for me.
It may be a case of getting some names down for them so I know how many I am looking at stocking as it would be a bespoke order for the factory.

Hope this helps..

Regards
Martin

 

[flecc]

I have real doubts that the dongle could work with the older first series unit as fitted on the Giant Lafree and earlier BikeTec Flyer models Martin. It was not only the speed regulation that was different, the power regulation method of the older unit was also.

So if Panasonic can do it, the 26 volt version would most likely be for the newer unit only, but that's no problem since the new unit outnumbers the old to a vast degree. Over six years Giant sold just 20,000 of the Lafree models worldwide. Derby Cycles alone probably sell as many Kalkhoffs as that every year and the new unit is used in more than 20 makes of e-bike.

As for the 26 volt dongle sales, they'll be most use to the derailleur geared bikes, since the hub geared bikes can be altered to just over 20 mph/33 kph just by a cheap change of the rear sprocket, and many have done that already. It's more expensive to do that with a derailleur and difficult to even 18 mph due to the confines of the top gear sprocket minimum size. I'd guess ebay could work wonders for the dongle sales, at least until rivals get hold of them too.

Even with 20mph/33kph assist limit, the range crashes by a third or more as many have found, so 50 kph would be a brief experience for most, especially so if using the 10 to 12 Ah batteries.

 

[Martin@e-bikeshop]

I have real doubts that the dongle could work with the older first series unit as fitted on the Giant Lafree and earlier BikeTec Flyer models Martin. It was not only the speed regulation that was different, the power regulation method of the older unit was also.

So if Panasonic can do it, the 26 volt version would most likely be for the newer unit only, but that's no problem since the new unit outnumbers the old to a vast degree. Over six years Giant sold just 20,000 of the Lafree models worldwide. Derby Cycles alone probably sell as many Kalkhoffs as that every year and the new unit is used in more than 20 makes of e-bike.

As for the 26 volt dongle sales, they'll be most use to the derailleur geared bikes, since the hub geared bikes can be altered to just over 20 mph/33 kph just by a cheap change of the rear sprocket, and many have done that already. It's more expensive to do that with a derailleur and difficult to even 18 mph due to the confines of the top gear sprocket minimum size. I'd guess ebay could work wonders for the dongle sales, at least until rivals get hold of them too.

Even with 20mph/33kph assist limit, the range crashes by a third or more as many have found, so 50 kph would be a brief experience for most, especially so if using the 10 to 12 Ah batteries.

Hi flecc,

You are right about the motor variants, I'm sure the dongle's will only be for the later models, these of course being more popular. But hey, this may be a good point for people to consider an upgrade if their bikes are over 6 years old and with the option of a dongle on a newer model.

As for the hub gears yes the sprocket can be changed, but this may just be an option so that the standard gearing on the hub geared bikes can be remain un-altered.

As for the range, Im sure as with every advantage there has to be a dis-advantage. In this case yes the range will be limited however speaking to some of the German guys in relation to the Bosch dongle; they said that because of the extra assistance speed a lot of them were using 'eco' as opposed to 'high' power that they were previously using, therefore the range wasn't affected as much and evened out a little.

Only time will tell, I will be testing variants like range on the Panasonic when we have the dongle's in.

Regards
Martin