## Bike rollers

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Capt Slog
Posts: 1957
Joined: Tue Nov 22, 2011 11:31 am

### Bike rollers

I'm building a set of bike rollers.

I don't have any plans and I've only ever seen them in pictures, so I'd like to know some measurements which would help me set them up correctly, or at least give me a starting point to experiment with.

What I need to know is the distance between centres for the pair of back wheel rollers, and the roller diameter. From this I can work out the points of contact on a back wheel and space my rollers accordingly.

Ta

edit to say...
A quick google says around 300mm for a 700c wheel, but doesn't give the roller size used for this spacing, this is the problem because I'm guessing it's fairly critical.
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De Sisti
Posts: 1086
Joined: Sun May 27, 2007 20:04 pm

### Re: Bike rollers

How much do you think the whole project will cost?

Capt Slog
Posts: 1957
Joined: Tue Nov 22, 2011 11:31 am

### Re: Bike rollers

De Sisti wrote:How much do you think the whole project will cost?

Nothing.

It's all built from bits of scrap which I've cobbled together.
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ManOfKent
Posts: 376
Joined: Thu Sep 13, 2012 12:08 pm

### Re: Bike rollers

I'm not sure the distance would be that critical - probably better to err on the side of too far apart rather than too close.

Assuming you know the angle at the hub formed by imaginary lines to it from the rollers, you should be able to work out either the centre-centre distance between the rollers, or their radius, whichever you don't know, using simple trigonometry.

schweiz
Posts: 1618
Joined: Sun Aug 31, 2008 18:51 pm

### Re: Bike rollers

Elite E-Motion Rollers

Rear Rollers 85 mm OD and C-C 255 mm

The distance from the mid point between rear rollers to the front roller must be equal to, or slightly greater than, your bike's wheelbase

Capt Slog
Posts: 1957
Joined: Tue Nov 22, 2011 11:31 am

### Re: Bike rollers

ManOfKent wrote:I'm not sure the distance would be that critical - probably better to err on the side of too far apart rather than too close.

Assuming you know the angle at the hub formed by imaginary lines to it from the rollers, you should be able to work out either the centre-centre distance between the rollers, or their radius, whichever you don't know, using simple trigonometry.

I don't know this angle, hence the question.

Thank you to Schweiz for answering it, that will give me base to work from, and it might even be just right.
"Dinosaur" "... horrible human being", BR Mod.

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ManOfKent
Posts: 376
Joined: Thu Sep 13, 2012 12:08 pm

### Re: Bike rollers

Capt Slog wrote:
ManOfKent wrote:I'm not sure the distance would be that critical - probably better to err on the side of too far apart rather than too close.

Assuming you know the angle at the hub formed by imaginary lines to it from the rollers, you should be able to work out either the centre-centre distance between the rollers, or their radius, whichever you don't know, using simple trigonometry.

I don't know this angle, hence the question.

Thank you to Schweiz for answering it, that will give me base to work from, and it might even be just right.

There are loads of Google images of bikes on rollers and it looks like there's a variety of angles depending on the design.

Glad you're making progress.

Capt Slog
Posts: 1957
Joined: Tue Nov 22, 2011 11:31 am

### Re: Bike rollers

Thought I'd give an update.

I've been a bit busy over the last couple of weeks, (Mum in hospital for a knee op, out now and doing fine), but last night I asked eldest son to give me a hand in the shed and we put together a prototype. A couple of lengths of wood for each side, into which went the axles of the rollers. The rear rollers are modified luggage conveyors, the front one is tubular table leg with some bearings fitted.

With no fixings whatsoever, I didn't really expect it to hold, but we put a bike on it to check the fit, and of course we then had to try it .

No, it didn't all fall apart, sorry. We both had a go at turning the rear rollers, whilst the other held the bike steady on the static front roller. We found this quite difficult, the rollers are heavy and even though they are free turning, they still take a bit of moving; there's unlikely to be any need for extra resistance.

Next, a belt to drive the front roller. We found an knackered inner tube and cut the valve off it. This went over all the roller to get the tension right (back roller of the rear set and over the front). And we tried again.

Ye gods, that's frightening. We were in a confined space between two work benches, so luckily there was something to hold onto at the sides. After a couple of near misses we were able to let of go of the support for a few seconds. Looking at our lash-up, we realised that the floor of the shed was wonky and so was our frame, so we decided to call it a night before we built any extra lumps.

The results were encouraging, and it looks as if it's going to work with a bit of tweeking. I'll post some pictures when I get it into a space big enough to take some.
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rob churchill
Posts: 257
Joined: Thu Aug 23, 2012 20:05 pm

### Re: Bike rollers

Tacx Antares

distance between centres of real rollers - 26.5cm
distance between centres of rearmost and forward roller - 115cm. This is adjustable by about 5cm to allow for different wheelbases of bikes - the instructions give the impression that getting it right is quite important for handling. You may be able to download a copy of the instruction sheet from the Tacx website.

Riding the rollers is not a problem, took me about 10mins to get the hang of it, the convex curve of the rollers probably helps - but I still can't get started without something to hang on to.

Good luck with it.
I have a policy of only posting comment on the internet under my real name. This is to moderate my natural instinct to flame your fatuous, ill-informed, irrational, credulous, bigoted, semi-literate opinions to carbon, you knuckle-dragging f***wits.

GiantMike
Posts: 3162
Joined: Tue Aug 11, 2009 09:41 am

### Re: Bike rollers

Don't look down or you'll wobble.
my power improvement experiment blog

Rule number 100: It's your bike and your money and your time; do what you like with it and ignore other peoples' rules. Except this one.

keef66
Posts: 8712
Joined: Tue Apr 29, 2008 09:46 am

### Re: Bike rollers

GiantMike wrote:Don't look down or you'll wobble.

Sound advice for a variety of activities

Capt Slog
Posts: 1957
Joined: Tue Nov 22, 2011 11:31 am

### Re: Bike rollers

Managed to get a bit more done this weekend, and got the rollers together well enough to think that it was worthwhile. Up until yesterday it seemed like effort required to pedal was far to great, it was like climbing ALL the while, okay for training you'll say, also good for cardiac arrests I would reply.

The problems came from sloppy, throw together work. It just needed a bit of firming up.

Here is Chip Slog having a go.....

and a close up of the rollers....

They are nearly finished, just need some feet and some jockey wheels for holding the belt in the right place; it tends to wander around a bit.

Total cost so far £2.60, I had to buy some threaded bar.
"Dinosaur" "... horrible human being", BR Mod.

Quis custodiet ipsos custodes?