Sram Sparc, side fell off.

alex

Pedelecer
Sep 15, 2007
43
0
Edinburgh
I had a problem with a fairly new Carrera Sparc with the Sram Sparc drive system. I have ridden about 160 miles & while out on a dark cold evening ride the motor completely cut out, also lights on mode selector died. I rode home easily enough without power, once in the warm with decent lighting found the entire plastic hub cover had come adrift, a plastic lock nut must have worked loose without me noticing, a jolt threw the cover off. I dont think there has been any damage, anyone with Sram motor should check this nut is well tightened.
 

rooel

Esteemed Pedelecer
Jun 14, 2007
357
0
If you tighten the large black nut it should not work loose again, but remember this is the way into the inside if you ever need to look there or are just curious, so do not overtighten it.
 

alex

Pedelecer
Sep 15, 2007
43
0
Edinburgh
Thanks Rooel. I feel familiar with the Sparc innards thanks to previous threads (remember Krauterbuter?), but hope I will not need to go there, well perhaps a peek inside when I have the wheel off. All seems to be running well today after swapping to a fully charged battery, I will watch that nut in future. The range of my NiMH batteries seems to be well down of late, partly my pedalling effort is less due to a dodgy back these last few weeks. But wondering if the colder weather could have much effect? I was getting 16 miles plus (sometimes 20 miles), now sometimes only 11 miles. I suspect my puny input is the main reason, I probably should give up the bike until the back is fully restored., but it is a slow process.
 

flecc

Member
Oct 25, 2006
52,761
30,348
All batteries hate the cold Alex, my NiMh speeds are down in the last few days, and when the cold snap started it finished off my remaining Li-ion battery.

Add to that your back problem and those speeds sound reasonable. I'm sure a warmer spell when your back is mended will return the old performance.
.
 

rooel

Esteemed Pedelecer
Jun 14, 2007
357
0
I certainly found on Friday when a cold north wind was blowing over Edinburgh that my Lipo was not quite so "zippy" as usual, but I, and it, were still able to make a first attempt with 20" wheels and the Sram Sparc system on Dublin Street, all the way from the bottom up to St Andrews Square, with a rest both for me and the battery at the lights 100 metres from the summit. However, that same wind which was diminishing the battery was blowing on my back lending its own assistance. I tried a NiMh today (just to discharge it and keep it in good condition) but found that although the air temperature was higher, performance was sluggish even compared to the diminished frost-bitten performance of the LiPo the previous day.

As for range, I have given up trying to measure how far a battery will power the motor. With a pedelec-only system it is just impossible to keep the motor constantly on by pedalling at under 15mph for 10 to 20 miles or more, whereas with a throttle and no pedalling a more accurate measurement could be obtained. I doubt if the range on the Sram Sparc system is much affected by the rider's input at it appears to contribute no more or less than the rider himself contributes. Therefore in first gear going slowly up a hill the demand on the battery may be the same as it is on the flat pedalling and travelling faster. There are of course many other variables, and in a comparison between the NiMh and the Lipo the 10% over-voltage of the latter may give an impression of longer range simply because the better acceleration takes the road speed up to the motor cut-out point very much faster and then if speed can be kept at just 16mph, with the pedals in top gear for a while, no demand at all is made on the battery.

There are of course many other variables, and I now assume, as a simple rule of thumb, that a battery will do 15 miles, planning a trip on that basis, taking a spare if the range is likely to exceed that distance, or two spares, if likely to be over 30 miles.

Alex may not be too keen to switch to Lipo cells at present having just bought his bike but I can assure him that that 10% over-voltage and 1kg weight saving transforms the Sram Sparc system. He would no longer notice his bad back.
 
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alex

Pedelecer
Sep 15, 2007
43
0
Edinburgh
Reduced range.

Interesting to hear your Sram Sparc experiences Rooel. I certainly look forward to the 18.5V Lithium boost when the NiMh batteries have expired, for now I do not feel particularly dissatisfied I just noticed a big reduction in the miles I was covering on one charge & feel this illustrates the difference rider input can make. Because my pedalling effort changed overnight when I was afflicted by a sore back the reduction in range & speed was very noticeable. Previously I adjusted gears so I continually pushed against moderate resistance & so quickly accelerated to cut out at 15.5mph, & stayed at high speed more thus saving on battery power. In my enfeebled state I barely push the pedals at all, the riding position is upright & I turn the pedals just enough to keep the motor operating, if I had a throttle option I would doubtless use it to the max. & not pedal at all. I ride at lower speeds with the motor providing nearly all the motive power, seldom topping 15.5mph. Miles per charge has probably dropped from 16 to as low as 8 with cold a contributing factor. I am on the mend now so with my programme of back strengthening exercises I should be able to measure my recovery in terms of miles per charge. Racing up Dublin Street will be my attainment goal.