gwhy

the wrap on a 9t will kill a chain in a very short time ( thats why they are so rare ) , 10T is about as small as you would want to go. the one in the link it looks like it could be modded to fit the motor output shaft on the oset motors as long as it has a 12mm id.. I still dont know why you dont go bigger on the rear it will be so much cheaper ( if your bike has the 219 sprocket adaptor ) and there is no benefit in reducing the front over increasing the rear.

Dont think there is... A 10T is about as tight as 219 chain can go. why dont you just increase the real sprocket ?

8s of lifepo4 will be equivalent to 24v sla as regards the voltage , but will give you much better performance and it will work on your 24v controller .. there will be very little voltage say ( unlike sla ) so you will have a higher top end anyway and this will also mean that you will have more power.

No I dont think it will be a option to remove the hvc as there will have to be a fair few other modifications that would have to be done to the controller .. ( the hvc will be there for a reason ) .. you could look for a after market 36v or 48v controller something like this http://kellycontroller.com/kds72100e100a24v-72v-mini-brushed-controller-p-761.html or even sometihng like this may be ok to try if you want it in a hurry and cheap :-) http://www.ebay.co.uk/itm/36V-800W-Speed-Controller-Box-Electric-Bike-Scooter-Brushed-/251638297450?pt=LH_DefaultDomain_3&hash=item3a96cfb36a .. I have no idea on how this controller will perform but for the price it may be worth a punt.

If you just replaced you're 24v with 36v then is will either work or it wont. Some controllers have a hvc built in so higher voltages can not be used , I think this may be more on the 24v controllers than the higher voltage ones. I think some people have used 36 on a 24 with success so I think there may be different controller models used on the range of the 24v bikes.

looks like this you can specify cell chemistry for this bms suppler.. but I expect that any supplier will have this option if you contact them. http://www.aliexpress.com/item/24V-8S-li-ion-battery-BMS-with-Balance-function-and-Max-60A-continuous-discharge-current-for/1724240995.html

I would doubt the 6000mah claim unless they are only pulling mA when they were tested.. but sony and panasonic do make the highest power density 18650's ( as long as they are genuine ) but this is more in the region of 3000mah each ( the last time I looked ) you will need to know what the over current spec actually is as it may not be high enough for our purpose.. yes they used to use these in the tesla cars but around 8000 of them and the cars are run on a much higher voltage than the bikes so on paper not as much current is required.. there are e-bike batterys made up of 18650's but these tend to have quite a low max discharge current ie a max of around 30-40A and are normally used for e-bicycles.. off road e-bikes can require a lot more than this sort of current limit..

you could use a CA ( cycle analysis ) to turn the bike off at a pre-set voltage but these are quite expensive, but on a plus side it will also give you a lot of performance information and will allow you to pay around with different throttle responses and configurations.

http://www.ebay.co.uk/itm/24V-25-6V-60A-LiFePo4-Battery-BMS-LFP-PCM-SMT-System-8S-3-2V-eBike-Battery-8x-3V-/321048902720 this is a link for a lifepo4 8cell bms http://www.ebay.co.uk/itm/BMS-for-24V-25-6V-8S-LiFePO4-Battery-Pack-50A-10A-limit-With-Balance-/161637237107?pt=LH_DefaultDomain_0&hash=item25a2548173 I can only find ones for lifepo4 at the moment ( these are the most common ) ... here are some general links for bms suppliers: but postage cost can be quite expensive http://www.bestechpower.com/pcmbmspcbforli-ionli-polymerbatterypacks/ https://bmsbattery.com/66-bmspcm

without knowing how that particular alarm is powered is difficult to say if you can wire then on to a switch... if it can be wired from a single on/off switch then it can be wired so it automatically come on when th ebike is turn on , but it will still involve plugging and unplugging the balance leads from the battery if you wanted to remove the battery. The type of bms to buy would depend on what battery chemistry and the number of cells you intend to go for as lipo and lifepo4 have different specs , hk do not sell bms boards so you will have to buy through ebay .. i will try and find some links for suitable bms if you think it will be helpful.

if you are confident wiring up batteries then you could purchase a bms ( approx £30 delivered ) to fit to the battery permanently.. and by the correct type of charger to charge through the bms ( approx £30 delivered)

yes just 1 of these will do the job but i would recommend having 2... one of each set of 4 cells ,, but you can not leave it connected to the battery all the time as it will drain the battery's.. you will have to plug it in when you are using the bike and remember to unplug afterwards.. another draw back with these small alarms is the connections are quite fragile and can easily be damaged with the constant plugging/unplugging . but will work..

if you are considering lipos then 4S will be a good jump in power ( 33.6v hot off the charger ).. the only problem is that you will have to monitor the lvc manually as the controller is setup for 24v.. so you will have to power the bike down when the voltage gets no lower than around 27v ,, running the battery lower than this will/may permanently damage the whole battery and make the battery unstable , if you what something that is a little more forgiving and nearer the standard voltage HK now sell lifepo4 battery's these are 4S2P each and are 8000mah each so you will need 2 battery's to make up a 24v 8ah battery. I dont know what the lvc is set for on the controller on the 24v bikes so you will need to test but if you use the lifepo4 then you need to stop riding when the voltage is at around 18v and the hot off the charger voltage for lifepo4's will be around 29v .. no matter what chemistry you choose always balance charge them using a li balance charger.

I am very supprised that some dealers are supplying them ( if indeed they are lipo), these batteries may give years of trouble free service ( and I would certainly hope they would for the price!!). A built in bms has many advanages and do help reduce the risk of a major thermal event but on the flip side a bms can also be the cause of a thermal event and depending on the type of chemistry that the bms is attached will determine how big of a thermal event and the amount of damage it will cause. All batteries have potential to cause fire but some chemistries are more flammable than others. As with any chemistry I would always charge in a fire safe area (a kitchen worktop is not a fire safe area :-)) and never charge unattended , I know of to many battery fires that could have been avoided and the people are always surprised and never thought it would happen to them . What I am trying to say is please dont get complacent about the dangers of all high density batteries (not just lipo) .. know what you are dealing with.

I can not imagine for 1 minute that "oset dealers" will sell to the public ( without a massive disclaimer ) if the battery's contain lipo cells... Its one thing understanding the dangers that surround lipo's as a user and knowing how to identify that something is wrong with a battery ... but to be sold as a plug n play (and care free) battery ... is not a good way to go. I am a big fan of lipo but I also know the potential problems that can happen .. maybe boost can make there packs up using a safer chemistry to justify the high cost of there packs.

I would recommend to get a lot more information on the boost battery's before committing to buying/using them.. maybe invite the guy that assembles them to post the specs in one of the battery threads on this forum ... They may be very good batteries ( what chemistry are they ? lipo or lifepo4 and what are the C ratings) , but it would worry me not knowing the spec/reliability of the bms or the battery's used.. I would want to know at what current the bms uses to balance the cells and also what is the cell charge cutoff voltage and resume voltage, cell lvc, what is the peak current of the bms and has it got over a over current trip and is it auto resettable. do you have inside knowledge that they are "good" batteries?.

The lifepo4 battery's that hk sell are rated at 30c so more than good enough ... if its 4X 12v battery's wired in series then its 48v , A watt meter is a very good investment for anyone with a oset ( or any electric bike ) no matter what chemistry you are using. if you do use cell monitors on the battery's then don't leave them connected when not in use as they will drain your battery.. Edit: If you are going for lipo then for a 48v 10Ah battery you will need a total of 12cells and if you go for the 5000mah lipos then each cell will need to be paralleled to make a 10000mah battery if you go for lifepo4 then you will need a total of 16cells for 48v , I would go for 4x 4cell packs , the lifpo4 batterys are 8000mah

everything you need to know about the use of lipos is in this thread http://www.trialscen...ion-directions/ HK also now do a lifepo4 chemistry rc battery ( a little less of a fire risk but you still have to treat with respect ) they are a little more expensive but I think worth the extra as they tend to be a little more forgiving chemistry... I think the lvc is around 38v but not totally sure... which is border line for a 12s lipo ... maybe worth testing the lvc of your controller. 2x22.2v lipos is 50.2v hot off the charger..

everything you need to know about the use of lipos is in this thread http://www.trialscentral.com/forums/topic/34845-oset-batteries-lithium-lipo-conversion-directions/ HK also now do a lifepo4 chemistry rc battery ( a little less of a fire risk but you still have to treat with respect ) they are a little more expensive but I think worth the extra as they tend to be a little more forgiving chemistry...

please don't rely on the lights on the throttle as a indicator to SOC the lights on the throttles are designed for sla chemistry which discharges in a totally different fashion to Li... also please never charge these battery's unattended and always charge in a fire safe area. please don't get complacent just because it has a bms..

yes I can see that it wil be slow and running on 24v.. why dont you try 48v, your controller may be ok with it, but the gearing may be way to high of on 48v so the motor will get even hotter..

:-) , I have used both types of systems and have hard data to support my claims but I do understand and agree that a brush less system can be much harder to get tuned in and is not always plain sailing. I make and sell coversion boxes for using regular cable throttles (they are my own design). I have also seen a similar device online that sells ebike stuff in China but don't know of anyone that has one from China. If you would like more info then drop me a pm.

it looks like the above fork can use a disk brake calliper .. the front wheel is the wrong way round. But its coming along nicely .. What motor are you planning to use, is it the same one you were going to use for a bmx ?

Just a couple of points :-) Brushed motors are heavier and bigger compared to equivalent power of brushless (and normally a lot more expensive). Direct drive the the rear wheel from the motor is a very easy way to do it but there are more advantages in gearing the motor down before driving the rear wheel and the extra weight is worth it , you will still be lower weight than a brushed motor ).. the current that a controller needs to be able to deliver is also different on a brushless system , you adjust your required top speed go gain the torque you require and this also lowers the current needed ( this is far more complicated than this but this is the general idea..) If I was building a conversion then I would go brushless all the way as it will work out cheaper in the long run, less maintainance, lighter and smaller . ( lighter and smaller is always good on a trials bike ) Magura and domino pot throttle are expensive and are both not to good for this application ( some will disagree with this ,,) stick with a hall type throttle or better still you can get a hall conversion that so you can use any normal cable throttle you like.

The T12 is sla and I think the beta is also sla the T14 I believe is Li-ion 3.7v cells ( or similar ) I cant imagine any off the shelf bike ever being sold with lipo as standard at the moment, Im not sure what the big bikes uses but I expect its lifepo4 but not sure on the format/type.. A lot can happen in a few years with battery tech so your going to have to re-look when the time comes. Im sure oset is working towards a lithum based battery ( they will be silly not to ).