N+1: A fast commuter reverie

[cycle tramp]

As for the discussion battery lights vs dynamo lights, why not use both? I do.... dynamo lights are always handy when the battery lights run low on juice, and battery lights are handy when fixing your bike in the dark

[Brucey]

Interesting that you had a broken pulley as well Brucey. I still have not got to the bottom of why mine broke so quickly. Was it a manufacturing fault ? - The bike was brand new. Or is it possible that somehow a stone got between the pulley and belt and cracked it ? Repair costs look shocking as well.. mine was fixed under warranty but I will be on my own with this soon.. Hmm.. maybe instead of buying a spare belt drive I should buy a spare chain, chainset and sprocket

this (steel) pulley (not my bike BTW) was either cast or formed using powder-met processing. It looked like the sort of material that might not weld at all well, but it welded well enough to permit a repair. The repair was needed on the ID; the spline had worn. This is very common on belt-drive bikes because the belt tension pulls the sprocket one way on the driver all the time regardless of the driving torque, and the sprocket orbits the driver, wearing all the time. By contrast with a chain drive the torque pulls the sprocket against the splines and the sprocket tends not to 'orbit' the driver and wear in the same way.

Some belt drive pulleys are aluminium not steel and these are more vulnerable to damage. Both cast and powder met steel parts tend not to have the same fatigue life as wrought material; if a tooth broke off the pulley it could have been accidental damage (a stone like you say) or it could have just been simple fatigue; the belt preload may do as much damage as the service loads through pedalling.

IME many belt drive setups are just rather poorly made. If they were the same cost as chain drive I could understand it but the parts cost many times more. I can treat my most used chain drive IGH bike to a brand new chain and sprocket and the cost is about £7.50. They last a year or two, even with minimal maintenance. The current chainring has 'done' about 20 chains....

cheers

[Greystoke]

I got blown off the road this morning in that awful head and side wind.
Turned round and drove to work.....safer. I'd done 100 continuous work day cycle commutes on Wednesday... Pity to break it up.

[pwa]

I like a robust, simple and reliable commuter with a dyno hub, I only use 3 of my 15 gears, I need a rack and mudguards and a bottle cage.
I prefer 26" wheels but that's just me.

When I read "I only use 3 of my 15 gears" my eyes immediately went right to see if you declare where you live. Lincolnshire. That explains it. I live in Wales and I use every one of my 27 gears. This illustrates how a person's idea of a commuter will vary with the precise nature of the commute.

[Greystoke]

Yes, my commute is undulating. We do have hills tho!

[robc02]

My commute is an undulating rural 10 - 15 miles each way, depending on which route I choose. The bike I mainly use is based on a 1970s/80s steel frame that is reasonably nicely built but a bit heavier than a lightweight of its day. It has dynamo lights that I leave on all the time (well its a lot of bother to lean forward and switch them off ) and a Sturmey Archer FM (four speed medium ratio) hub. Tyres are currently Vittoria Voyager Hyper in 32mm but I previously used Conti GP4S in 28mm. The rest of the build is fairly standard stuff - Campag chainset, Look pedals, drop bars, Tektro deep drop (73mm) brakes, Ambrosio rims.

There are lighter, nimbler bikes out there, but I have happily used this on quickish group rides and not felt at a any disadvantage except when revving out on a long tailwind stretch.

Ideally I would like a 531 or similar frame for a slightly less harsh ride, and maybe drum brakes - I have them on another bike and do like them - but the SA one with dynohub is quite a heavy chunk. I wish they did one with a better quality and lighter dynamo. Also, I would lose the FM ratios, but could probably live with that.

[cycle tramp]

0The bike I mainly use is based on a 1970s/80s steel frame that is reasonably nicely built but a bit heavier than a lightweight of its day. It has dynamo lights that I leave on all the time (well its a lot of bother to lean forward and switch them off ) and a Sturmey Archer FM (four speed medium ratio) hub. Tyres are currently Vittoria Voyager Hyper in 32mm but I previously used Conti GP4S in 28mm. The rest of the build is fairly standard stuff - Campag chainset, Look pedals, drop bars, Tektro deep drop (73mm) brakes, Ambrosio rims.

Sounds interesting! Any chance of a photo

[robc02]

:twisted:

0The bike I mainly use is based on a 1970s/80s steel frame that is reasonably nicely built but a bit heavier than a lightweight of its day. It has dynamo lights that I leave on all the time (well its a lot of bother to lean forward and switch them off ) and a Sturmey Archer FM (four speed medium ratio) hub. Tyres are currently Vittoria Voyager Hyper in 32mm but I previously used Conti GP4S in 28mm. The rest of the build is fairly standard stuff - Campag chainset, Look pedals, drop bars, Tektro deep drop (73mm) brakes, Ambrosio rims.

Sounds interesting! Any chance of a photo

Can't take a new photo as It is without front wheel at the moment, due to repairs being needed, but here are some from a few years ago:

WinterBike2013 by SturmeyRob, on Flickr
WinterBikeFrontBrakeEtc by SturmeyRob, on Flickr
WinterBikeRearBrakeEtc by SturmeyRob, on Flickr

[Greystoke]

I like that.

[pwa]

I like that.

+1

I'd need a choice of gears to ride it around here, but if I lived somewhere flatter...

[cycle tramp]

Thank you ~ what a wonder commuting bike

[robc02]

I'd need a choice of gears to ride it around here, but if I lived somewhere flatter...

The FM hub gives gears of -33.3%, -14.3%, Direct, +12.5%. Currently that gives me approx 44", 57", 67", 76". I have also experimented with an AW (wide ratio 3 speed) which I found OK, but needed a bit more care in choosing the direct gear as it was a big jump to the ones either side.

For those wanting lower low gears without losing the top end, an option is to use the wider ratio 5 speed hub where 4th, or even 5th, is the "normal" gear. For instance this could give 33" 39" 50" 63" 76".

[Brucey]

I think that is a nice machine too. In many respects it is not so far away from my most-used bike. For many years I have used an SA 5s hub on 46/18 or 46/19 gearing (46/18 giving 46, 55, 69, 87, 104" gears) and this gives the best efficiency in the most-used gear, at the cost of the available low gears, of course. An alternative to this would be to use an AW so that 3rd is the most used gear; this could (eg with 42/22 gearing) give 39, 52, 69" gears.

http://ritzelrechner.de/?GR=SAS5&KB=46&RZ=18&UF=2161&TF=90&SL=2.6&UN=MPH&DV=gearInches&GR2=SAAW&KB2=42&RZ2=22&UF2=2161

With any SA 3s made in the last 80 years (! ) or so there is a slightly greater loss in gears 1 or 3 than is strictly necessary. Same goes for Shimano and Sachs/SRAM 3s gears too. Originally, SA hubs had rolling element bearings in the planet pinions (they were "the Rohloff of their day" if you like) and were slightly more efficient in the high and low gears as a consequence. I plan to modify a SA 3s hub to include rolling element planet pinion bearings, so as to make it as efficient as it can be. [BTW I don't think this can be easily done with the shimano and SRAM/Sachs models; the pinions are smaller diameter and probably won't take being hogged out to make room for the bearings so easily.]

cheers

[Greystoke]

Interesting concept but would roller bearings make a noticeable difference?
My commuter plan is probably an aw3 and add 2-3 cogs, half step 2 of them and have a much bigger cog for times when I need low gears.

[Brucey]

Interesting concept but would roller bearings make a noticeable difference?...

I think they probably will. About 1-2% is roughly what is on offer and this is about the same as you get with slightly better tyres etc; it just all adds up.

In some hub gears there are two gear trains in succession; in some of these hubs there have been two versions; one with and one without roller bearings on the planet pinions. I can honestly say that riding the hubs without is a bit like tromping around with custard in your boots vs the ones with roller bearings. You really notice that the intervals either side of the direct drive gear seem to have altered, because the efficiency so much changed. OK, the difference is liable to be x2 as great in that case (because there are two gear trains) but even so it is a very convincing demonstration that roller bearings on the planet pinions can make a difference.

cheers