Search found 83 matches

by asinus
7 Mar 2024, 5:37pm
Forum: Bikes & Bits – Technical section
Topic: AXA bottle dynamo repairs?
Replies: 14
Views: 807

Re: AXA bottle dynamo repairs?

Yhanks - that's what I've done. I've also checked the internal resistance again, and while I can't remember the values, it was low.
by asinus
6 Mar 2024, 9:40pm
Forum: Bikes & Bits – Technical section
Topic: AXA bottle dynamo repairs?
Replies: 14
Views: 807

Re: AXA bottle dynamo repairs?

Thanks again all.
I can now get it to light up one light at a time, i.e. from one pair of live and earth contacts, and it doesn't matter which, the right way up. Spinning the wheel faster got the voltage up to 7V - I didn't push it any faster. Does this add any useful information? At least it is now potentially partly usable.
by asinus
5 Mar 2024, 11:18pm
Forum: Bikes & Bits – Technical section
Topic: AXA bottle dynamo repairs?
Replies: 14
Views: 807

Re: AXA bottle dynamo repairs?

Thanks all. I have replaced it to keep on the road, but would sooner get it going again if I can.
I tested it again tonight on another frame, and it could generate more than 5V across all combinations of live and earth terminals - but it was running upside down so that I could get the multimeter probes in. I checked the resistance, which was low across all pairings.
Common things are common, so perhaps it was a connection problem, but the same lights and wiring work fine with the new dynamo, and neither worked with thee faulty one.
by asinus
2 Mar 2024, 9:48pm
Forum: Bikes & Bits – Technical section
Topic: AXA bottle dynamo repairs?
Replies: 14
Views: 807

Re: AXA bottle dynamo repairs?

Thanks - aha - I was testing on the DC setting (as I thought LEDs would only work on DC) - will check on the AC setting.
by asinus
2 Mar 2024, 9:42pm
Forum: Bikes & Bits – Technical section
Topic: AXA bottle dynamo repairs?
Replies: 14
Views: 807

AXA bottle dynamo repairs?

I have an AXA HR bottle dynamo that I bought maybe a year ago, but it suddenly stopped working two nights ago - fine when I left home but after a few hundred meters the front light reduced to standlight level and the rear went out completely. I've redone the connections, but no difference, and when I spun it with multimeter probes across one + and one earth terminal, it generated no voltage. I can't work out how to get into it despite undoing the screw at the base (and doubt if I could fix it if I could), but any experience or thoughts out there? Thanks
by asinus
2 Mar 2024, 9:29pm
Forum: Bikes & Bits – Technical section
Topic: Sturmey Archer 5 speed Hub - Slipping gears
Replies: 26
Views: 2443

Re: Sturmey Archer 5 speed Hub - Slipping gears

Alas, the two-lever system wasn't too good either. I had one in the 80s, which slipped in the lowest gear unless I back-pedalled a bit every few revolutions. It made riding up the mountain part of the Manx TT course in a gale - er - interesting.
by asinus
7 Feb 2024, 9:40pm
Forum: Bikes & Bits – Technical section
Topic: Converting derailleur to hub gear other than Rohloff
Replies: 22
Views: 1791

Re: Converting derailleur to hub gear other than Rohloff

My calculator tells me that your present setup gives a range of 571%, wider than any hub gear I know of, i.e. Rohloff or Kindernay. The thing to be careful of with fitting a multiple chainwheelwith a hub gear is that hub gears are designed with a minimum input ratio - that is chainwheel teeth divided by sprocket teeth (2 in the case of Shimano hubs, 1.86 with my old SRAM 7-speed, 2.375 with a Rohloff, I think): if lower than this, there's an increased risk of stripping the teeth of the sun pinion in the hub.
by asinus
29 Dec 2023, 5:35pm
Forum: Bikes & Bits – Technical section
Topic: Best material for a shim for seat post?
Replies: 50
Views: 2522

Re: Best material for a shim for seat post?

All depends on the relevant dimensions. To get a good fit I'd use a Vernier caliper (not that expensive) to measure seatpost and seat tube a try and find something of half the difference in thickness. Thus, when I wanted to fit a 25.8 (!) mm seatpost into a 27 mm seat tube, some stainless sheet 0.6 mm thick from an old fire surround was just the job. Alternative, if you have the exact dimensions, you might be able to get a shim off the peg.
by asinus
29 Dec 2023, 5:24pm
Forum: Non-standard, Human Powered Vehicles
Topic: Tadpole Tandem Trike Builder
Replies: 15
Views: 4860

Re: Tadpole Tandem Trike Builder

Have you considered a conversion from Roman Road Cycles (http://www.roman-road.co.uk/conversions/tandem.htm), which looks like the sort of thing you want for £1400 up? Just have to get the machine to and from deepest mid-Wales.
by asinus
21 Sep 2023, 9:53pm
Forum: Electrically assisted pedal cycles
Topic: Battery re-celling?
Replies: 6
Views: 4125

Re: Battery re-celling?

I have experience of this, twice. My 1999 Raleigh Select had its cells replaced by the Electric Bike Sales in Cambridge in 2012, and still has a range of 20+ miles 2300 miles, 70+ charges and 11 years later. More recently we got my wife's e-trike battery recelled through a concern called Electric Bike Battery Repairs - who actually engaged County Battery, who I think are based in Nottinghamshire to do it. I sent EBBR some pictures, as it didn't fit any of their standard patterns, and they arranged things (after payment), including transport by UPS - sending batteries is fraught. I found them by an online search.
The service was quick - a few days - but we had to return the battery twice under warranty after it packed up, probably due to speed humps on lousy Lancashire roads - so now my wife is careful to avoid the worst routes. Now done over 200 miles, but at a cost of nearly £500 for a 36V,11 Ah system (I think).

Hope this helps.
by asinus
18 Jul 2023, 9:56pm
Forum: Bikes & Bits – Technical section
Topic: Rohloff SPEEDHUB 500/14 Minimum Sprocket factor
Replies: 20
Views: 1303

Re: Rohloff SPEEDHUB 500/14 Minimum Sprocket factor

My understanding was that there's a minimum ratio of sprocket to chainring for hub gears because if it's too low, in bottom gear the force on the fixed sun pinions attached to the axle will strip the teeth of the (fixed) sun pinion which provides the reaction needed for the gears to work. I did this many years ago on a Sturmey Archer hub in South Devon. As the Rohloff bottom gear is so much lower than direct drive this is particularly relevant, although the minimum ratio is lower than that advised by Shimano for their hub gears.
by asinus
26 Oct 2022, 9:55pm
Forum: Bikes & Bits – Technical section
Topic: Larger sprocket (27t) for Nexus hub
Replies: 11
Views: 804

Re: Larger sprocket (27t) for Nexus hub

The other thing to remember is that hub gears usually have a minimum ratio of chainwheel teeth to sprocket teeth, to reduce the risk of excess force stripping the teeth on the sun pinion, and my recollection is that for most Alfine hubs it's in excess of 2.0, and Nexus might well be the same - best check before you fit an oversize sprocket.
by asinus
21 Sep 2022, 6:50pm
Forum: Bikes & Bits – Technical section
Topic: Which replacement sprocket and chain ring should I get for a Shimano Alfine 8?
Replies: 6
Views: 596

Re: Which replacement sprocket and chain ring should I get for a Shimano Alfine 8?

In the OP, part of the question was about raising the gear. That should be simple if you can access a sprocket with fewer teeth. The limiting factor with internal gear hunbs is usually at the low end - the ratio between the numbers of teeth on the chainwheel and the number on the sprocket has to be more than a certain value - for one version of the Alfine 8-speed it has to be above 2 according to an old manual I have. The reason for this is that a lower ratio (and therefore lower spread of gears) might strip the sun pinions.
Hope this helps.
by asinus
3 Sep 2022, 5:26pm
Forum: Bikes & Bits – Technical section
Topic: belt drive and IGH
Replies: 21
Views: 2013

Re: belt drive and IGH

Interesting to read experiences of the Enviolo. I have applied for a patent for a continuously variable hub gear on different principles with a wider range, should have less power loss and weigh less - but so far no UK manufacturer interested.
by asinus
3 Sep 2022, 5:18pm
Forum: Bikes & Bits – Technical section
Topic: Light fixing with bar bag advice please
Replies: 62
Views: 2296

Re: Light fixing with bar bag advice please

This is my home-made solution - a bit of handlebar bolted to a (steel) relfector bracket. I've made a few - best if bolted in two axes to keep it stable.
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