Tracer trike Conversion from fixed to 6 gear.

[stearman65]

Don't forget the derailleur mech. needs to sit outboard of the smallest sprocket in order to work.

I didn't know that but I assume my bike mechanic does. The way I intend to mount it, the lateral position is pretty flexible. Thank you.

 

[mickle]

The slot in the bracket on the top of that derailleur that you've overlaid would go underneath the rear wheel axle nut on a regular bike. The slot in the bracket slides over the axle. Other types screw into a threaded hole in the drop-out itself.

It's important that your derailleur placement matches this as closely as possible. It's been designed to function with this in mind. Locate it any more than a few mm away from this ideal and it'll not be able to influence the chain's passage over the sprockets.

So. it is a fairly straightforward job to provide a bracket which will provide a mounting point for the derailleur. However ... the derailleur (that's a very poor drawing of a very old example which predates indexed gears) jockey wheels will sit directly underneath the sprockets. Unfortunately there's a dirty great frame tube directly underneath the sprockets.

I think that you've bought the wrong trike. if you wanted super-low fixed gears you've bought the right one, but if you want a range of gears you should probably accept that this trike is not compatible with such a set up. And either take this back to the shop (if you think they've sold you the wrong thing) or sell it and buy something which suits you.

As it happens I am an expert in the area of provision of bike for people with disabilities. We sell new and refurbished, to individuals mainly, but also large fleets of adapted bikes to schools and local authorities. We see a lot of these trikes on our travels - usually old knackered ones in schools - because at one time this was one of the few disabilty trikes available in the UK. Things have moved on substantially since this trike was designed. But it has remained resolutely unchanged in design since its conception. I'd be interested to know how much one of these things costs new.

I'd have sold you one of these: http://www.getcycling.org.uk/details.php?id=674&c=194

 

[stearman65]

The slot in the bracket on the top of that derailleur that you've overlaid would go underneath the rear wheel axle nut on a regular bike. The slot in the bracket slides over the axle. Other types screw into a threaded hole in the drop-out itself.

It's important that your derailleur placement matches this as closely as possible. It's been designed to function with this in mind. Locate it any more than a few mm away from this ideal and it'll not be able to influence the chain's passage over the sprockets.

So. it is a fairly straightforward job to provide a bracket which will provide a mounting point for the derailleur. However ... the derailleur (that's a very poor drawing of a very old example which predates indexed gears) jockey wheels will sit directly underneath the sprockets. Unfortunately there's a dirty great frame tube directly underneath the sprockets.

I think that you've bought the wrong trike. if you wanted super-low fixed gears you've bought the right one, but if you want a range of gears you should probably accept that this trike is not compatible with such a set up. And either take this back to the shop (if you think they've sold you the wrong thing) or sell it and buy something which suits you.

As it happens I am an expert in the area of provision of bike for people with disabilities. We sell new and refurbished, to individuals mainly, but also large fleets of adapted bikes to schools and local authorities. We see a lot of these trikes on our travels - usually old knackered ones in schools - because at one time this was one of the few disabilty trikes available in the UK. Things have moved on substantially since this trike was designed. But it has remained resolutely unchanged in design since its conception. I'd be interested to know how much one of these things costs new.

I'd have sold you one of these: http://www.getcycling.org.uk/details.php?id=674&c=194
View attachment 138440

Hi Mickle
The mock up was just a mock up from an image that was easy to P/Shop out the items I didn't want to show. My trike was an Ebay buy, 1/5th of the price they are being sold new. The main reason i bought it was it dismantles & fits in my car easily, my car is my garage. I might have bought a recumbent but the least expensive folder I could find was just under £2k. The mods I make to mine will be temporary so I can revert to the existing set up if they don't work.

 

[raleighnut]

Going by this photo the only way to mount a derailleur mech would be a bracket on the furthest forward of the 3 tubes that are the rear axle assembly.

 

[stearman65]

That's the same one as I propose.

 

[Ajax Bay]

As @mickle says: "there's a dirty great frame tube directly underneath the sprockets" just where the derailleur (RD) must sit (ie directly under the 6 o'clock of the sprocket) to be effective, however the RD is attached to the frame. And no amount of photoshopping's going to move it. But I can see you like a challenge. Maybe cut the offending bit of tube out and provide its structural effect by an underbridge of some kind.
But please measure and tell us the distance between the current sprocket and the ground - from the images, it doesn't look a lot ~200mm . The bottom edge of the RD cage reaches about 180mm (short cage) below the axle (models will vary a bit) - or roughly 130mm below the sprocket. This implies a clearance of 70mm. Mmmm!?.
Had you considered a 3sp (or 5sp) Sturmey Archer hubgear option which might fit above the obstructing tube and give you the higher gears I think you seek, and much more possibly in the space available.

 

[raleighnut]

As @mickle says: "there's a dirty great frame tube directly underneath the sprockets" just where the derailleur (RD) must sit (ie directly under the 6 o'clock of the sprocket) to be effective, however the RD is attached to the frame. And no amount of photoshopping's going to move it. But I can see you like a challenge. Maybe cut the offending bit of tube out and provide its structural effect by an underbridge of some kind.
But please measure and tell us the distance between the current sprocket and the ground - from the images, it doesn't look a lot ~200mm . The bottom edge of the RD cage reaches about 180mm (short cage) below the axle (models will vary a bit) - or roughly 130mm below the sprocket. This implies a clearance of 70mm. Mmmm!?.
Had you considered a 3sp (or 5sp) Sturmey Archer hubgear option which might fit above the obstructing tube and give you the higher gears I think you seek, and much more possibly in the space available.

They will work mounted further forward

 

[Tim Hall]

Going further left field, what about a schlumpf speed drive? It's a fearfully expensive bit of kit that goes in the Bottom Bracket (where the front chain ring is) and allows the selection of two different gear ratios. Your already low gear ratio might impose too much torque though. It does get around the "how to mount the derailleur" question however.

 

[TheDoctor]

Or sell it and actually buy the right trike. I can't see any way of getting a freewheel block or a cassette on there, still less getting a derailleur in there too. It's a can't get there from here scenario.

 

[stearman65]

Hi Guys
Thanks for all the interaction, however until I get my hands on some hardware I won't be doing anything such as cutting. I have ordered some heavy duty jubilee clips to fasten a modified hanger I found on Ebay on the tube
, (my modification). I ordered 3 in case one breaks when bending it. Alistair is sourcing a derailleur, cassette/freewheel, hub, chain, cable & actuating lever. When I've got them I can start experimenting. If you look at the original pictures I posted, I mentioned the existing rear sprocket as being 105mm diameter, so the radius is 52.5mm. It fits on the wheels axle, & I mentioned the wheels were 24inch diameter, 12inch radius, or 300 ish mm, minus 52.5 = 247.5mm is the distance from the bottom of the sprocket to the ground. From my delving into the subject I believe there are 3 lengths of derailleur? short medium or long? I assume the short would give the best ground clearance. Whether that would be suitable, I assume Alistair will decide. I had considered a Sturmey Archer gear change but unless I bought a used Ebay item, it would be way over my budget. So for now, I'll wait & see what comes up, hopefully the weather will allow me to have a run in the local botanic Gardens tomorrow. Thanks again for the interphase.

 

[stearman65]

Or sell it and actually buy the right trike. I can't see any way of getting a freewheel block or a cassette on there, still less getting a derailleur in there too. It's a can't get there from here scenario.

How about a small wager? Incidentally I have done some sales business in my branch manager days, I had a good teacher, one of the things he taught me was never, slag off the oppositions wares if you want to keep a potential client interested.

 

[TheDoctor]

Equally, if you ask people for advice, you need to accept that the advice you get might not be what you want to hear. There's lots of geared folding trikes on eBay. Had you bought one, you'd be riding it now.

 

[stearman65]

Equally, if you ask people for advice, you need to accept that the advice you get might not be what you want to hear. There's lots of geared folding trikes on eBay. Had you bought one, you'd be riding it now.

Likewise!!!
I did search for about a month on Ebay, but didn't want a "Grandad / Grandma trike, lots of home made recumbent stuff & at the other end of the country. The day I went to view mine I also had an appointment at the local KMX agent for a test ride on one they had in stock, unfortunately he'd sold the machine I was to try out, so I bought the Tracer. I was running out of time to get my exercise regime going before my knee replacement. The budget KMX had been discontinued or run out of UK stock & would have been a struggle to get in the car. There was one on Gumtree locally, but after a few enquiries decided it was a scam.

 

[Ajax Bay]

I hope you'll share how you get on as I for one will remain interested. Bear in mind that (I suspect) most of those offering advice have multiple sets (could make up sets) of the hardware you say 'Alistair' is 'sourcing (a derailleur, cassette/freewheel, hub, chain, cable & actuating lever) in their spares boxes. You only need a short cage derailleur btw, as you will only have max 14 teeth to wrap. Ground clearance would remain an issue..

 

[stearman65]

I hope you'll share how you get on as I for one will remain interested. Bear in mind that (I suspect) most of those offering advice have multiple sets (could make up sets) of the hardware you say 'Alistair' is 'sourcing (a derailleur, cassette/freewheel, hub, chain, cable & actuating lever) in their spares boxes. You only need a short cage derailleur btw, as you will only have max 14 teeth to wrap. Ground clearance would remain an issue..

Hi Ajax Bay
Alistair is away this week, so it may be next week before I get to see the hardware, I did show him a couple of items before he went but I wasn't selecting correctly, in particular the hub to match the freewheel, not sure of the thread on his freewheel. Just been on Shimano's web site, but they give every dimension but the hub fixing thread I will certainly see this out one way or another. I'm used to forums & the sometimes adverse comments. I'm 76, been around, but it's 60 years since I built my bike with a Freddie Grubb frame, things have changed.