Heated grips

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Rob Frankhamr
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Re: Heated grips

Postby Rob Frankhamr » Fri Jan 03, 2020 10:24 am

No problems with that at all... if it works for you, then go for it... the grip heaters I have on the 'RS and on the 'RT are both old tech and work well enough for my use. They won't work with the BMW loom though or the Oxford controller... at least without modification. I've often thought about building an electronic controller for them but frankly, I've never got round to it.

I do feel, though, that it's relevant top point out that the Oxford grips will work considerably more efficiently with the Oxford controller they are designed for. They will use less power (except when on max), heat up more quickly and give a more stable temperature.

Rob
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Re: Heated grips

Postby vmx1200 » Fri Jan 03, 2020 12:15 pm

Thanks everyone my question seems to have really got this old thread "warmed up" :lol:

Haven't got around to fitting them yet but have noted one thing a potential purchaser should consider; the grips are open at both ends as I guess Oxford think all motorcycles have bar end weights so I will need to get some form of bar end stopper, there are plenty to choose from on ebay

Did a couple of hundred miles on the old girl on New Year's Day with a group of friends on bikes ranging from a 1928 Sunbeam to a new Honda Grom!!

The bike went flawlessly, if only she stopped as well as she goes; those ATE single pot calipers are woeful (and yes they were rebuilt when I did all the work on the bike this time last year inc braded hoses). I suppose this is because I can compare the brakes to those on the R-9t

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Re: Heated grips

Postby andyb » Fri Jan 03, 2020 12:23 pm

Rob,
I take your point, the new Oxford controller sounds like a better way of reducing the heat but I must admit that I don’t like how it bolts to the handlebars. An inevitable problem of an after market add on system.

I should have said that on my R100R I have LED bulbs in the speedo, tacho, rear light and pilot light and these reduce the power drain by around 4A so as well as running the heated grip I can also power a 3A heated jacket. This is with the standard BMW charging system.

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Rob Frankhamr
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Re: Heated grips

Postby Rob Frankhamr » Fri Jan 03, 2020 5:56 pm


I take your point, the new Oxford controller sounds like a better way of reducing the heat but I must admit that I don’t like how it bolts to the handlebars. An inevitable problem of an after market add on system.

On the Triumph, I simply the controller to the flat area in the middle of the handlebars. On the faired boxers, it obviously wouldn't be a problem... plenty of flat(ish) surfaces to stick it to but I'm not sure where I'd fix it on the unfaired bike. Probably find somewhere to fix a flat plate to stick it to. The mirror fixing hole is an obvious candidate although I'm not sure if/how it would work out... Might not be particularly pretty but it would work.

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Re: Heated grips

Postby andymcg » Sat Feb 08, 2020 6:18 pm

I Fitted Oxford heated grips with their V8 controller to "Walter" my K75 in Nov 2018 and found them nice and warm.
The controller seems to have packed up and while it will run them for a short period they cut out and sometimes don't restart. Apparently it is a common problem with the Oxford grips.
For simplicity I have ordered a replacement controller, £25 and hope it lasts longer.
I have seen somewhere on the WWW, the suggestion that to get two levels of heat from the grips it is possible to wire them in series for low heat and then in parallel for higher current and higher heat. Seems a better solution than the BMW two heat level system with a resistance wire for low heat.
Just wondering if anyone has done this, with either original BMW grips, or Oxford ( or other aftermarket) grips?
I am not convinced that having various heat levels is necessary: a simple on/off switch and turn on and off as needed may be simpler and more reliable.
There is a youtube video of making a replacement controller using a DC motor controller. Not too difficult looking but rather tedious.
https://www.youtube.com/watch?v=yWTX3i-ARcM
Wondering if anyone on here has done similar.
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Re: Heated grips

Postby george baker » Sat Feb 08, 2020 7:10 pm

Hi
that reminds me I was supposed to dig the grips out for Andy.

I have thought about using a pwm controller that you can buy cheaply on eBay, intended for multi LED displays.

https://www.ebay.co.uk/itm/Mini-DC-3V-3 ... SwuENeOGMf ----3-35V, 5A, 2 quid


https://www.ebay.co.uk/itm/12V-RF-Wirel ... SwooFeC3q6 -- 12V 6A, remote, also 2 quid

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Re: Heated grips

Postby Rob Frankhamr » Sat Feb 08, 2020 8:18 pm


I have seen somewhere on the WWW, the suggestion that to get two levels of heat from the grips it is possible to wire them in series for low heat and then in parallel for higher current and higher heat. Seems a better solution than the BMW two heat level system with a resistance wire for low heat.
Just wondering if anyone has done this, with either original BMW grips, or Oxford ( or other aftermarket) grips?
This idea was obviously put forward by someone with little or no electrical knowledge. The first thing you would need to know is whether the Oxford grips are designed to be run in series or in parallel. I have to admit that I'm not sure but I think they are normally connected in series, however, knowing that will only tell you why they won't be satisfactory. Lets look at both scenarios...

Grips designed to be run in series

Lets make an assumption that the grips on full power generate a total of 24 watts heat, that's 12 watts for each grip. Simplistically, this means that the grips will be operating on 6 volts, will draw a total of 2 amps (Volts x amps=Watts) and the resistance of each grip will be 3 Ohms (volts divided by amps = resistance) Now lets connect the same grips in parallel. Assume that the resistance remains at 3 Ohms (More on that later). We are now connecting 12 volts across two 3 Ohm grips. so each grip will draw 4 amps. What this means in terms of power output is that each grip is producing 48 Watts!! The system in total is producing 96 Watts and draining 8 Amps. Actually, it's not as bad as that. The resistance of the wire used inside the grip increases as it's temperature increases and this would actually tend to restrict the increase in power and therefore the heat but it's still very much the case that a grip designed to run on 6 volts at 2 amps will (a) get very hot and (b) lead a very short and interesting life if it is expected to work on 12 volts.

Grips designed to be run in parallel

If we keep to our figures of 24 Watts in total then it goes without saying that each grip will be producing 12 Watts and drawing a current of 1 amp (12 volts x 1 amp=12 Watts). The resistance of each grip will be 12 ohms (12 volts divided by 1 amp=12 ohms). This setup will work perfectly at 'full power' (i.e. with the grips arranged in parallel) but arrange the same grips in series and things aren't quite so rosy. Now each grip is only seeing 6 volts. 6 Volts into 12 ohms will draw a current of half an amp. Half an amp at 6 volts will produce just 3 Watts. Once again, the variation in resistance with heat will tend to make this not quite as bad as it seems but it remains the case that, on the lower setting, the grips will get barely lukewarm.

In short, running series grips in parallel will burn them, out... running parallel grips in series will mean they are useless on the low heat setting.

On of the things about electricity is that it has this nasty habit of playing tricks on you unless you do the arithmetic.

The motor controller idea is valid but a bit clunky... it's probably as cheap to get a replacement Oxford controller and seal it thoroughly with silicon before fitting it.

Rob
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Re: Heated grips

Postby andyb » Sat Feb 08, 2020 9:00 pm

BMW and Oxford (and most others?) run in parallel so that if one grip goes down the other continues to work.
Agree with Rob - if they are designed for use in parallel then they will not be hot enough wired in series.
The actual figures for BMW and Oxford Commuter grips are about 36W when in parallel (3A) which gives each grip a resistance of 8 ohm and a heat output of 18W.
In series they would run at 4W each......lukewarm.
I have used Oxford Hot Hand grips (again about 3A / 36W in parallel) to make heated grips for microlights and all that is needed is a simple on/off switch. If the grips ran at a higher current (like they do on say the Triumph triples) then a low power setting is useful and running in series might work. But remember that our Airheads have quite low output alternators so may not be able to run high current heated grips.

When I had a Triumph Sprint I could dry wet grips out on the high power setting......but the setting was too hot for normal use.

Using the right gloves is important - some gloves have little insulation on the grip and more on the outside of the hand and I find these work well with heated grips.

AndyB
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Re: Heated grips

Postby andymcg » Tue Feb 11, 2020 11:57 pm

AndyB and Rob,
Thanks for the information on the physics of the parallel/series option. I now see why it is not the good idea I thought it might be.
The Oxford controller I have does not have a removable back, like some shown on youtube, and there is no visible evidence of it being filled with water. But it doesn't work! I have ordered a replacement and will fit that as a direct swap and hopefully it will last longer. If it fails prematurely I may go down the PWM controller route but there is a limit to how much time it is worth spending to save £25.
I got about 18 months from previous Oxford controller, so out of warranty.
It's not grim up North!
since 1994 a R100R and from Oct 2015 "Walter" K75S, and from Aug 2016 R850R!

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Re: Heated grips

Postby andymcg » Wed Feb 12, 2020 12:11 am

AndyB and Rob,
Thanks for the information on the physics of the parallel/series option. I now see why it is not the good idea I thought it might be.
The Oxford controller I have does not have a removable back, like some shown on youtube, and there is no visible evidence of it being filled with water. But it doesn't work! I have ordered a replacement and will fit that as a direct swap and hopefully it will last longer. If it fails prematurely I may go down the PWM controller route but there is a limit to how much time it is worth spending to save £25.
I got about 18 months from previous Oxford controller, so out of warranty.
It's not grim up North!
since 1994 a R100R and from Oct 2015 "Walter" K75S, and from Aug 2016 R850R!

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Re: Heated grips

Postby Galactic Greyhound » Wed Feb 12, 2020 12:21 am

AndyB and Rob,
Thanks for the information on the physics of the parallel/series option. I now see why it is not the good idea I thought it might be.
The Oxford controller I have does not have a removable back, like some shown on youtube, and there is no visible evidence of it being filled with water. But it doesn't work! I have ordered a replacement and will fit that as a direct swap and hopefully it will last longer. If it fails prematurely I may go down the PWM controller route but there is a limit to how much time it is worth spending to save £25.
I got about 18 months from previous Oxford controller, so out of warranty.

Hi Andy (andymcg),

You should let Oxford Tech Dept know about that Controller failure.
The item should last longer than 18 months and, being a reputable Company, they may wish to examine the faulty unit re the cause of premature failure.
At the very least you will be doing your bit to help a British company improve their products! :smile:
Ced.

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Re: Heated grips

Postby vmx1200 » Fri Oct 23, 2020 6:29 pm

Just reviving this thread again

I have just fitted a set of K75S bars to my RS as the riding position was getting too much for my senior citizen neck and thought it would also be the ideal opportunity to fit the Oxford touring heated grips I received last Christmas.

Reading the threads on here there seems conflicting info as to whether the right hand grip will fit over airheaded twist grip, I have read that you have to machine the twist grip tube down (?to remove ribs) where other recon they fit. I don't want to remove the original grip which is in good condition and find the Oxford one doesn't fit.

The Oxford grip has an internal diameter of 25.6mm

Anyone have a twistgrip as fitted to a 78RS that they could measure?
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Re: Heated grips

Postby vmx1200 » Mon Oct 26, 2020 12:46 pm

I will answer my own question in case anyone in the future wants to know it.

The Oxford "Hotgrips" grips require, according to fitting instructions, a throttle tube of a consistent 25.6mm and any raised areas must be smoothed off.

The throttle tube on my machine is 26.25mm in diameter with two raised ribs along the tube a couple of mm wide, the diameter here is increased to 26.5mm.

The only way to make them fit would be to machine down a throttle tube, if I can find one cheap will get my friend to machine it down, the question is are all airhead throttle tubes the same?
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Re: Heated grips

Postby george baker » Mon Oct 26, 2020 12:52 pm

Hi
my post-- this thread--Thu Dec 26, 2019 1:34 pm

I fitted the "Commuter" grips with no problem, only having to remove a tiny amount of plastic on Both R100R and to a K75

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Re: Heated grips

Postby vmx1200 » Mon Oct 26, 2020 2:08 pm

Thanks George, I read that, not sure if the Commuter grips are a different internal diameter as the fitting instructions are not available on the Oxford website; all of the others state the 25.6mm diameter. I am loath to try machining out the plastic core of the grip as I have no idea where the heating elements are.
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Re: Heated grips

Postby andymcg » Mon Oct 26, 2020 2:12 pm

Thanks George, I read that, not sure if the Commuter grips are a different internal diameter as the fitting instructions are not available on the Oxford website; all of the others state the 25.6mm diameter. I am loath to try machining out the plastic core of the grip as I have no idea where the heating elements are.
The difference in size doesn’t seem large. Maybe heating up the grips, with a hot air gun would allow sufficient “give” to allow the grips to be forced on? They wouldn’t work loose!


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Re: Heated grips

Postby vmx1200 » Thu Nov 12, 2020 12:32 pm

I decided to buy a second hand throttle tube from Motoworks as was surprised when it arrived and I removed the grip that the tube was made of plastic :shock:
Does anyone here know when did they change from a cast alloy throttle tube to a plastic one? The bit with the bevel gears is obviously alloy and appears to be identical to my original.

The good news is that the Oxford grip will fit over the tube with no machining required
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Re: Heated grips

Postby vmx1200 » Sat Nov 21, 2020 1:51 pm

I thought I would wrap up my contribution to this thread, the newer style of plastic throttle tube I received is of a smaller external diameter than the original alloy one fitted to my machine and the Oxford Hot Grips fit both sides without any problems.

The biggest challenge was fitting the controller, I had thought of using the mirror mounting on the left control assembly however I would have had to fit it upside down as the cable wouldn't clear the switch gear.

I have fitted K75S bars to my machine along with a heavily modified R100 crash pad, these are the same width as the original RS bars but about 50mm higher which makes for a significantly improved riding position (never had this problem 40 years ago).

The controller is easily accessible attached to the crash pad with a a hidden cable tie and epoxy; the mount in the middle of the crash pad is for my Ultimateappons phone case which I use as a satnav.

Perhaps not as elegant as the way it left the factory but certainly more usable and I can always put it back as it was and I have all the original bits

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Re: Heated grips

Postby andyb » Sat Nov 21, 2020 8:43 pm

Why not use a BMW 2 way rocker switch? I also did not like the Oxford controller and so simply used the standard BMW switch with resistance wire reducing the power in one of the positions. My bike had previously had heated grips so it was easy to change the wiring from the BMW grips to the Oxford ones, but you could do the same.
TBH just an on / off switch is probably enough!
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