Basic noob question re 15mph limit.

[riverboat2001]

I understand that legally you can't go more than 15mph using power, but on all but the steeper hills my legs are going faster than the pedals can allow.
Is there anyway to change this, ie by fitting a larger cog?

Not trying to "beat the system" but i seem to be wasting a lot of energy.

 

[Eagle]

I find the same thing on the flat with my FreeGo Eagle which has 7 gears (Shimano). I bought this ebike primarily to go up hills, so I am not really complaining.
In an ideal world I would like a 9 gear cassette but obviously that would
be too wide to fit inside the rear forks.

What bike do you have?

IF your bike has a removable front chainwheel, then you could fit a larger one (say 52T as opposed to 48T). This would give an 8% higher gearing.
You would also need a new (longer) chain to suit.

If the front chainwheel is not removable you would need to fit a new chainwheel and crank assembly.

This link shows an example of removing/refitting Shimano cranks and chainwheel:
Benno's Blog & More: How-To: Install/Remove New Style Shimano Cranks and Chainrings

You could also reduce the level of pedal assist or switch it off completely on the flat but obviously this has no effect on the gearing.

 

[tillson]

What sort of bike is it?

If it has a Panasonic drive, then fitting a smaller rear sprocket will help with the problem that you describe. However, that will lift the assist speed beyond 15 mph which is technically illegal.

If your bike has a hub motor, then altering the ratio between the front chain ring / wheel and the rear sprocket(s) will also achieve the same result, but because you aren't altering the assist speed, the bike will remain legal.

 

[riverboat2001]

Hi, I have a Powacycle Salisbury.

I'm not very technical, but can follow instructions or videos.

I've written to them so will see what they say.

I guess a short-cut to make it a better workout would be to switch it off completely when i reach 15mph and just pedal, but unfortunately the keyswitch is difficult to operate whilst cycling.

 

[flecc]

The Salisbury had a pedelec sensor built onto the back of the chainwheel which makes simply changing it not an easy option. One simple solution adopted by A to B magazine and others since is to bolt a new larger chainring onto the existing one, effectively enlarging it at low cost. Here's a photo from the A to B magazine showing that modification:

 

[Deleted member 4366]

I'm not sure I understand your problem.

Are you saying that the motor stops power too soon so that you're pedalling with your own power most of the time, or are you sating that you can't pedal fast enough at 15mph?

If it's the former, you need to check that there's not a speed restrict connector on the controller (2 single wires joined in a loop). If so, just disconect them, otherwise you need a higher voltage battery, which will give a proportional (to volts) increase in motor speed.

If it's the latter, and you can't pedal fast enough because your gearing is too low, then you have the option of either fitting a larger chain-whhel with say 53 teeth, or you need a new rear free-wheel set with an 11 tooth top gear, which you can get from Cyclezee.com.

You need special tools to fit both.

 

[riverboat2001]

The Salisbury had a pedelec sensor built onto the back of the chainwheel which makes simply changing it not an easy option. One simple solution adopted by A to B magazine and others since is to bolt a new larger chainring onto the existing one, effectively enlarging it at low cost. Here's a photo from the A to B magazine showing that modification:

View attachment 4178

Hi, thanks very much, that looks a bit easier.
Looking at the picture, which is the added chainring? the one nearest the reader?
I'm assuming that i would also need a longer chain?

Lastly, how would this affect the hill climbing - I have a very steep hill on my way to work!

 

[neptune]

The new, added chainwheel is the one with the chain on, which is furthest from the camera. I have done the same modification on my old Powabyke Euro. Regarding hill climbing, which gear are you using to climb that hill now? If you are using your lowest gear, with the modification, it will feel like using third gear when you are in gear one. You will need a longer chain. How much longer? count the teeth on the new chainwheel. Subtract the number of teeth on original chainwheel. Halve the result . Extend the chain by that number of lincs. The new chainwheel can be bolted either side of the original, whichever suits.

 

[riverboat2001]

I'm not sure I understand your problem.

Are you saying that the motor stops power too soon so that you're pedalling with your own power most of the time, or are you sating that you can't pedal fast enough at 15mph?

If it's the former, you need to check that there's not a speed restrict connector on the controller (2 single wires joined in a loop). If so, just disconect them, otherwise you need a higher voltage battery, which will give a proportional (to volts) increase in motor speed.

If it's the latter, and you can't pedal fast enough because your gearing is too low, then you have the option of either fitting a larger chain-whhel with say 53 teeth, or you need a new rear free-wheel set with an 11 tooth top gear, which you can get from Cyclezee.com.

You need special tools to fit both.

Basically what happens is when on the flat i get to 15mph and then, where i would change up a gear, i'm already in the top gear, so have to stop pedalling until I've slowed down enough.

 

[flecc]

As Neptune says, that steep hill might be a problem. If you are already using bottom gear and only just manage to climb it, the added chainwheel wouldn't be a good idea. In that case, changing the rear freewheel with it's sprocket set to one having a smaller top gear one as d8veh suggests would be a better option, only raising the top gear.

 

[riverboat2001]

As Neptune says, that steep hill might be a problem. If you are already using bottom gear and only just manage to climb it, the added chainwheel wouldn't be a good idea. In that case, changing the rear freewheel with it's sprocket set to one having a smaller top gear one as d8veh suggests would be a better option, only raising the top gear.

I'm really sorry, i don't really understand any of that last sentence

And yes i am already in bottom gear, and finally made it up the hill for the first time today

 

[flecc]

I'm really sorry, i don't really understand any of that last sentence

And yes i am already in bottom gear, and finally made it up the hill for the first time today

No problem. Obviously adding the extra larger chainwheel isn't an option for you, so the only way to increase your speed for a given pedalling rate is to raise the top gear only. That means the smallest sprocket at the rear needs to be smaller yet. At present you have a six sprocket freewheel at the rear with it's smallest sprocket probably a 14 tooth one. That needs to be replaced with another six sprocket one having a smallest sprocket with less teeth, either 11 or 12 teeth will do if your present one has 14 teeth.

The problem is whether one is obtainable, the one d8veh mentions probably has too many sprockets and will probably be too wide for the frame. At present I only know of six gear ones with 14 tooth smallest sprockets, unless someone knows different.

 

[Eagle]

d8veh & flecc

you need a new rear free-wheel set with an 11 tooth top gear, which you can get from Cyclezee.com.

Many thanks for that useful information.

In my case my FreeGo Eagle has the 7 speed Shimano Derailleur with ultra-low 1st gear, as per one of the photos on here:
http://www.axcess-electric-bikes.co.uk/electric-bikes/freego-eagle

I would like to just change the 14T top gear to 11T, but at worst I could get a new 7 speed Shimano cassette with an 11T top and swap my original ultra-low 1st gear onto the new set.
Is the latter option possible, by the way?
I definitely want to retain my ultra-low 1st gear!

What differences in quality are there with the various Shimano sets?
What Shimano parts do you advise for my Eagle?

 

[flecc]

I've never been able to shift those top gear sprockets the way Shimano have them jammed on, but it should be possible. From what you've said you probably have a megarange freewheel with a very large sprocket of about 34 teeth, dropping straight to a 24 tooth one.

SJS say in Google that they have a seven speed megarange 11 to 34 in stock at £20.42, but it's not shown in their website pages so best ring them. That one is an HG50 quality.

HG50 is one of Shimano's best quality multi-sprocket freewheel or cassette type, the freewheel with twin bearings. The Cadet range are their cheap single bearing budget ones.
.

 

[Deleted member 4366]

That's easy then. Get a used 53/39T chainrset from Ebay for about £20. you probably won't need to lengthen your chain. I never did on the three that i converted. If for whatever reason you need to pedal up a steep hill with no motor, you find a twig and hook the chain over onto the smaller ring, and then for normal powered riding, hook it back, so you don't need a fron derailleur.

Double chainrings are a lot more plentiful than single ones because they're used on road bikes. Try and get one with a matching left-side crank.

Here's one for starters.
CAMPAGNOLO RECORD 170mm Chainset + Chainrings 39-52 Good Condition | eBay

 

[Eagle]

flecc,

You are correct about the original Shimano fitting. It is a Megarange Hyperglide HG 14-34T freewheel.

It seems as though the 11-34T version was discontinued by Shimano a year or two ago, much to the annoyance of many bikers who are desperate to find them.

I guess that I had better leave well alone and just reduce the battery assist, or switch it off altogether on the flat. As I mentioned earlier I really need this for hill climbing.
Ideally it would be nice to have more speed on the flat but there we are!

For my next ebike I will bear this factor in mind.

Do you have any suggestions for electric bikes using either crank or hub formats to accommodate both ultra-low 1st and a higher than 14T top gear?

 

[Deleted member 4366]

Cyclezee does a 7 speed free-wheel with 11T top gear that's an easy replacement: Just remove the old one (with free-wheel tool) and screw on the new one. I haven't seen removable gears on electric bike free-wheels. In fact I've only seen them on cassettes. Many of us have spent hours seaching out 11T free-wheels, but the only ones we've found is DNPs, which you can get from Ebikes.ca with huge shipping charge, or Ebike Solutions in Germany - also with high shipping costs.

If you have a front motor, you can change the whole back wheel to a cassette one from Ebay or car boot sale for not a lot, then you can get whatever gearing you want.

 

[Deleted member 4366]

Do you have any suggestions for electric bikes using either crank or hub formats to accommodate both ultra-low 1st and a higher than 14T top gear?

As I said above, get a double chainring. If you want to be professional, fit a front mech as well otherwise use a twig like we do.

 

[flecc]

The 7 speed freewheel that d8veh suggests will fit onto your rear motor and in your frame, but you'll need to check the large sprocket size. You obviously need that 34 tooth sprocket that you have at the moment. It will also need a new handlebar control to use the 7 gears since you only have six at present.

From what has been posted previously by a trade member about the Powacycle Salisbury, you may not be able to change the chainwheel since it apparently has a proprietary pedelec sensor incorporated into it which is set up for their controller. That would need checking to see if it's possible to swap that over to a new chainwheel though.

To recommend a new bike to meet your needs, we really need a start point like your budget since there are so many e-bikes on the market.

 

[jateureka2]

Eagle,
The FreeGo Hawk I have uses a Tourney 7spd drivetrian with 14-34T freewheel and a front 48T chain ring, so you may want to check the Shimano website before fitting the 11-34T freewheel (if you can get one) to confirm the rear derailleur can handle that range.

If your controller is the same as mine then you can disconnect the restrictor by unplugging the two single grey wires at the controller. This may be illegal where you live (I'm in Australia) so do so at your own risk.