Cycling UK Forum

[XAP]Bob wrote:.....why wouldn't you use them.......

er, because the hub usually ends up full of swarf?...

one of the big problems for suspension on a bicycle is the low frequency weight transfer induced by pedalling. The usual outcome (be it suspension via springs or tyres) is bobbing. Apparently the tyres fitted to the RSW16 were not too bad for rolling resistance, but most people who rode one (myself included) simply couldn't abide the bobbing. I have owned a number of moultons, and their chief drawback (for me) was always bobbing. For many years I used two MTBs with suspension, and although it worked quite well and I was very glad to have it (Moots YBB and Giant NRS) neither bike was (I felt) really suited to out-of-the-saddle riding.

biker38109 wrote: ↑25 Feb 2025, 10:00am.....wind is like solar in that it is too temperamental......

and there you have it in a nutshell, the inconvenient truth that means we may never get to the point of making all our energy sustainably. The policy of our government (like many others) is to make up any shortfall in energy production (eg. on cloudy, windless days) via other means. In the very short term, this means gas-fired power stations, but in the longer term, we will almost certainly be relying on nuclear energy. The only truly predictable source of renewable energy is tidal, but that comes in distinct bursts, about twice a day, and so far no-one has really cracked the rather difficult engineering required; not in a cost-effective fashion, anyway. Not for the power generation itself and not for the energy storage systems mandated either.

MGate wrote: ↑23 Feb 2025, 9:35pm.....Would welcome your opinion Brucey!

my opinion is that rubber (having properties that vary so much with temperature) might be inherently unsuitable for making a suspension with. Despite its undoubted cleverness and simplicity, any long term user of a 'mini' equipped with Moulton-designed rubber suspension in 'dry' subframes will be familiar with two things;

1) a ride quality that was initially iron-hard on cold days.

2) in the summertime, the suspension would occasionally get all 'hot and bothered', giving a rather mushy ride.

I think that what saved it in many cases was the bumpy roads; these worked the suspension hard enough that the rubber soon warmed itself up, even on a cold day. I'm not at all sure the same thing applies elsewhere eg. on bicycles.

If the flexitor units are just too stiff, it may be possible to greatly improve them for your application. IIRC the flexitor units provide springing, damping, and pivot bearings all in one unit; clever stuff. IIRC the NS front suspension comprises four flexitor units acting together. Simply replacing one of them with a geometrically identical pivot containing bearings alone will give a system with 3/4 stiffness, 3/4 damping etc. which might be just what you want. Alternatively. If you set the preload differently on 1/4 flexitors you should (because the flexitor units will be fighting one another) wind up with a lower overall spring rate. The potential disadvantage of this approach is that the damping will be about the same as if all four flexitor units were acting in unison ie. with the same preload.

IMHO this problem is very tractable for anyone prepared to wield a drill and some hand tools.

Nearholmer wrote: ↑24 Feb 2025, 5:10pm Patent it quickly, and partner with a producer.

(Maybe test a couple of prototypes first!)

easier said than done. All suggestions welcome.

Nearholmer wrote: ↑24 Feb 2025, 1:23pm.... If only there was universal compatibility between all the components we can now choose from!

I have invented a gizmo that (in terms of shifting) does just that, since it allows the attributes of a shiftmate to be unobtrusively combined with parts which control the force seen in the shifter, thus allowing almost any combination of parts to be used.

rogerzilla wrote: ↑22 Feb 2025, 2:34pm I was in a hurry.....

that is not a very nice chainset and you are not the OP. This is what Robert M. Pirsig referred to as a 'gumption trap'. I think the chances of successful removal would be increased immeasurably if three simple things are done;

1) use epoxy resin to temporarily hold the crank extractor in place despite the stripped thread. This will obviously not be full strength but it should allow 300-500 kgf extraction force to be used, and that (in combination with the other things) might be enough.

2) use 'rubbodraulics' to help you; first use something (eg. a grub screw as previously described) to temporarily fill the hole in the BB spindle. Next, make a 'reaction plate' (RP) from steel of about 3mm thickness. This should be of a size (about 12mm x 12mm) that makes it a good sliding fit in the square crank opening; the RP transfers the extractor load (via intervening rubber layers) to the BB spindle, in so doing, allowing a helpful hydrostatic pressure to be generated, perhaps only briefly.

3) use modest heat to help you. Obviously if you can make the crank hot whilst the BB spindle is cold then there is (comparatively speaking) a very big effect. But even if the two parts are equally hot the differential CTE works in your favour, thus modest heat (eg. from a kettle full of boiling water) is usually beneficial.

If there is much slack in the extractor threads, it is probably worth preloading everything (eg. by using the extractor to apply a load of about 300kgf) prior to using a hammer on the extractor at just the right time. This would be just after starting to pour the hot water, ideally whilst the Al is hot and the steel is still cold, thus allowing the 'rubbodraulic pressure spike' to be of maximum benefit..

Note in addition it is usually possible to repair a failed extractor thread.and this makes a very good long-term fix.

PH wrote: ↑23 Feb 2025, 12:15pm.....Whatever the wrongs.... it is what a lot of people do......

if you are saying that some folk can behave irrationally, I'd agree......

MGate wrote: ↑23 Feb 2025, 5:24pm.....until we sort out the Flexitor units stiffness....

what exactly is the problem that you are trying to address?

531colin wrote: ↑23 Feb 2025, 4:09pm So is it the case that the F. mech. design makes the granny to mid shift require more force than the mid to big shift, ie the leverage varies with where the F. mech. is in its stroke?

yes; depending on the chainline/adjustment, the arm on the FD can be nearly vertical, at which point the cable MA is greatly reduced and the shift force is increased. It is possible to clamp a special bracket along with the cable, using the pinch bolt. The special bracket can have the gear cable draped over it, thus changing the fulcrum point and potentially improving the cable MA. This can even be selective, in that the arm rotates ACW as you shift onto bigger chainrings, allowing the special bracket to get itself out of the way altogether for the middle to big shift provided it is positioned correctly.
The special bracket can be made from flat sheet (suitably cut/filed/drilled) or an M5 washer welded to a short length of old spoke. In any event, it is a very good idea to brace the bracket against the arm, so that the bracket cannot rotate further ACW without the arm, no matter how tight (or loose) the pinch bolt is.

bikepacker wrote: ↑23 Feb 2025, 1:43pm.... I agree that was a good set up used it on Airnimals many year ago. One drawback was no quick release on rear wheel so need to carry extra tools.....

I have designed an SA AW conversion that;

1) spaces the rear hub flanges much further apart.

2) reduces rear wheel dish.

3) is much lighter.

4) can use rolling element pinion bearings for high efficiency.

5) will accept a modified cassette, typically containing up to 7 sprockets.

6) is designed to be QD from the outset, eg using a pushrod, not a pull-chain.

There are such things as QR track nuts, which are lever-operated. However, QRs are never instantaneous, plus my design of self-tightening ring spanner weighs just 20g so is hardly burdensome to carry.

531colin wrote: ↑21 Feb 2025, 12:52pm I have seen children (small hands) make the front up shift by reaching across and using their right hand!

IIRC shimano tried to make this (and one-handed doubleshifts) a lot easier, by stipulating that the correct DT lever setup (for a double) was so that the front shift occurred when the LH lever is nearly vertical.

PH wrote: ↑22 Feb 2025, 11:57am.... On a triple used in that way, the smaller cogs which were being dismissed as unnecessary upthread, get a lot more use.

the same arguments still apply; I suspect this indicates a reluctance to use the front shifter.

stuwilmur wrote: ↑23 Feb 2025, 10:40am.... I think the thread pitch is 1/mm.....

FWIW you can easily be certain of this; a bog standard M6 bolt also has a 1mm pitch and makes an excellent ad hoc thread pitch gauge.