New bike build, hub gears & brakes, belt drive

[[XAP]Bob]

Why can't the brake cable run down the downtube to the BB and then along the chainstay, no need to go down the seatpost to get there...

[Brucey]

Or use a bolt with a square shoulder and a wingnut on the outside.

that is OK so long as the bolt is still able to come out easily; a fully captive bolt may make wheel removal difficult.

A wing nut is OK but probably needs something to prevent it backing out should it come loose; a tether or R clip or something. I like to use a nyloc or similar when I use a nut.

I have found that (with care and quick dousing) it is possible to tack weld a stainless nyloc nut to the back of a stainless clip.

Oddly enough the bike that is most troublesome to me has a bracket welded on for the reaction arm; it is all as it is meant to be but the arm ideally needs to be bent a little, which with it being short, ain't easy. Until I get round to doing this, I have to put spacers in, which is fiddly...

cheers

[bobc]

"Why can't the brake cable run down the downtube to the BB and then along the chainstay, no need to go down the seatpost to get there..."
that would be because of the cable clips on the frame.
If I went down the downtube, I could use the "bare inner" solution going straight to the brake lever on the hub - that would utilise both brazed on shifter bosses as cable stops.....
I wonder how long the plastic inner cable rubbing thing under the BB would last with brake loads on the cable? Anyone tried it?

[bobc]

First long commute on this bike today. Result is a fail really, the belt with glass fibre reinforcement is simply not strong enough, Gates used carbon for good reason! It works fine mostly, but I can't stand on the pedals - when I do this I can actally see the tooth pattern appear on the top surface of the belt & the belt can unship. So I'll have to source a superior belt: back to the internet...... !!
In this build I have a 40 tooth 'chainring' witha 170mm crank, effective "chainring" radius is thus 40*14/2pi = 89mm so I'm putting about twice my weight into tension on the belt (let's call it 2400N). When I find something suitable I'll post back!

[[XAP]Bob]

Shame - but not entirely unexpected...

[bobc]

Indeed - got home OK (without standing on the pedals). What went well? the shifter cable arrangement was excellent and I'm pretty sure it would be a very worthwhile modification to my old bike. The drum brakes are also excellent, as is the dynamo front light. Things I'll need to change: belt (obviously); 35mm back tyre is too big for the frame, I'll change that to 32mm; my mudguards wouldn't look out of place on a tractor, I'll swap those. I got a new adjustable quill stem (£12 on ebay) & that does a great job. Meanwhile, I'm back on the old alfine11 bike..... I must say I liked the feel of the new bike, it seemed to fly along pretty good in spite of the belt issue; I'll come back when I find a carbon belt (or other technology that can cope with 7000N tension....)

[Brucey]

.... I'll come back when I find a carbon belt (or other technology that can cope with 7000N tension....)

dare I suggest a boring old.....

chain (ahem)...?

as a stand-in?

cheers

[mig]

do gymnasium spec exercise bikes use a belt?

[CJ]

I'm struggling to find a problem a belt solves that a chaincase hasn't answered already and answered better - apart from persecution by the fashion police!

[[XAP]Bob]

I'm struggling to find a problem a belt solves that a chaincase hasn't answered already and answered better - apart from persecution by the fashion police!

Holding up my trousers?

[bobc]

"I'm struggling to find a problem a belt solves that a chaincase hasn't answered already and answered better - apart from persecution by the fashion police!"

Whatever: there are several solutions to the problems of bicycle power transmission, all have their +'s and -'s. Chain + indexed deraillieur is cheap and efficient (good luck putting an effective chaincase on that!) but dirty and maintenance intensive. Frankly they are nice for about 3 rides after you buy the bike.. or just one on a bad day..... belt + IGH costs more & is less efficient. Which you think is best should depend on how you personally weight those pros and cons. My motivation here, for the benefit of everybody, is to try to reduce that cost.

You're welcome

[Brucey]

I admire the aspiration and I am all in favour of the experiment.

But.... derailleur chains are a significant problem and belts don't solve that. Chains with IGH's are, well, mostly painless, really. A squirt of lube once every few hundred miles, chuck 'em in the bin and get another (less than five quid) after a few thousand miles.

Most of the dirt on my bike comes from the road, not the chain, and I'd hardly describe what I do -which works OK for all weather use- as 'maintenance intensive'.

cheers

[CJ]

"I'm struggling to find a problem a belt solves that a chaincase hasn't answered already and answered better - apart from persecution by the fashion police!"

Whatever: there are several solutions to the problems of bicycle power transmission, all have their +'s and -'s. Chain + indexed deraillieur is cheap and efficient (good luck putting an effective chaincase on that!) but dirty and maintenance intensive. Frankly they are nice for about 3 rides after you buy the bike.. or just one on a bad day..... belt + IGH costs more & is less efficient. Which you think is best should depend on how you personally weight those pros and cons. My motivation here, for the benefit of everybody, is to try to reduce that cost.

Well done with knocking down the straw men. But my man of steel is using an IGH and a chaincase. That can be heavy, but spend as much technology on it as has gone into trying to make a belt work on a bike and we'd have carbon-fibre chaincases instead of chainstays, fully integrated with the frame structure and adding very little weight.

And modern derailleur gears are so reliable, need such little attention, that they surely could be enclosed. Before long I think we'll see that happen, probably with a reverse-mounted mech in front of the cassette, so as to minimise bulk, and single-sided rear wheel support from the torsionally stiff chaincase - perhaps with just a quick-release seatstay on the left - to facilitate tyre changing without removing the wheel. That's my vision of the future bicycle.

I think you're being very courageous in pursuing the path of the belt, but that it will prove in the fullness of time to be one of the bicycle's evolutionary dead-ends.

[thirdcrank]

... That's my vision of the future bicycle......

Put it into a fully-faired recumbent and we might be campaigning to be allowed to ride on motorways..... As fossil fuel runs out, we may even be grumbling about slow motor vehicles getting in the way.

[cycle tramp]

My motivation here, for the benefit of everybody, is to try to reduce that cost.

And i for one, am grateful. i've really enjoyed tuning into this thread, and following the build up of this bicycle, and the development of a home made belt drive system... and while i may not build my own belt drive system, this thread encouraged me to speak with the lazer cutters where i live to get a chain guard sorted and to consider that my next bike build should have a front drum brake...

..are belt drives a dead end? personally i couldn't say... from my point of view the chain drive of a bicycle has had thousands and thousands spent both in terms of man hours research and development as well as yen, sterling and dollars. i don't think that a belt drive for a bicycle has seen that level of investment. At the moment i don't know of a single bicycle internally geared bicycle hub that has been designed for its use... but this is now, and we are never at the end of things, always in the middle.... but i can imagine a future where bicycle belt drives are employeed by folding bicycles, to prevent the risk of an oily chain coming into contact with nice clothes, and used in all terrain bicycles, where sand, grit, dust and mud would otherwise shorten the life of a chain, and of course commuting bicycles. Perhaps in the future, belts will be employeed in a new sort of variable transmission, whereby the chain wheel is replaced by an array of expanding or contracting teeth, set in a circular disc..

...i can understand the mention of chain cases and they are all well and good, until you have a rear puncture and then they become another barrier for the swift removal and refit of the rear wheel. If a chain case was to be employeed, in any bicycle design, then lets follow Mike's design and build frames feature rear stays on one side of the wheel only....

...we have to remember that ages ago in the 1980's a group of men showed their own development to a large number of bicycle companies, many of whom dismissed their design as a fad... and thereby missed out on the boom which was the mountain bike.

i look forward with interest in the next development of your wonderful bicycle, and how you have overcome this current difficulty.
Thank you once again for your words and photographs, without people like yourself this forum would be a greyer and duller place.

mat cycle tramp