Changing the derailleur on a Windsor?

[nin26]

It didn't take long - I've started modifying the Windsor ...

I've put a lovely new seat post on it - I'm now waaay up in the air and can whip along much more efficiently.

I find the ride a lot smoother than when I was bouncing up an down on the old suspension post with my knees round my ears (that's how it felt anyway!) There's only one problem - it has highlighted how undergeared the bike is on the flat and slight downhills.

In an ideal world, I think I'd gain a 7th and 8th gear. Although I suppose 1st gear is a useful "get you home" gear if the battery failed, I'd be willing to sacrifice it if it meant getting a 7th gear instead as I'd use 7th a darn site more than I'd be needing 1st.

So, can it be done and what will I need to buy? I'd probably order it all from the local bike shop and get them to do the honours, but I want to know what the best option will be and the difficulties involved (if there are any). I also want to be able to check prices out before I go to the bike shop so I know I'm getting the right thing for me.

I'd like it to be a good quality replacement, preferably better than the original equipment (I find the gear change a bit woolly and not always as slick as it could be).

Any suggestions and advice gratefully received!

 

[flecc]

The Windsor is very low geared with ratios of 37" to 73". You really need to keep something like the 37", but the top gear needs to be something like 85" or more.

The usual solution is to fit a Megarange freewheel on the rear, since these have a normal sprocket range plus a very large inner sprocket to give a low "get you home" gear.

I fitted these on both of my bikes for the similar reasons, and the ratios on my Q bike are 35", 50", 57", 67", 80", 92". As you can see, that's about what you want. The parts you need for the rear are the Shimano Cadet Megarange 13 to 34 tooth freewheel from Wiggle on this page, and an Acera rear mechanism on this page which is megarange capable. Your SIS one won't be.

Unfortunately that's not the end of your troubles on this bike, since it has a tiny chainwheel, probably only around 38 teeth and too small for the job, so that would have to be changed for something like a 44 tooth which would then give you gears of 34" to 88", ideal for what you want.

That means buying a spider and chainring to go in place of your present chainwheel and it might mean losing your present chainguard, though it could just be big enough. A local cycle dealer could supply a spider and crank with a 44 tooth chainring to suit.

One possible complication is if you have a pedelec sensor attached to the present chainwheel, you'd need to check that.

If you don't care at all about having a low gear, a cheap option woukd just be to go for the chainwheel which might give you about 43" to 85" gears, but I'd need you to count how many teeth there are on your present chainwheel to confirm that, and advise the new size of chainring you need.

Meanwhile, here's the Q bike conversion page including the information of interest to you.
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[nin26]

Hmmm, I'm thinking that if I'm going to do this, I might as well do it properly and go the whole hog with the megarange as well as the chainwheel, even if I have to wait until I have some holiday and can book the bike into the bike shop for a day or two. I don't want to be paying again in a few months time because it still isn't quite right.

Next question - given that I'm about as technically minded as a fridge magnet - what will the pedelec sensor likely look like so that I can tell if there's one on the chainwheel? If there is one on the chainwheel, is there a way around the problem or are we talking major (and expensive) alterations?

Also, is there a more efficient shifter I can get to go with the new megarange setup? Or do I just stick with the one I have?

It was interesting reading your Q bike link - I hope I can make my Windsor a lot more efficient, but I don't have the ability or flair to be that clever about it!

 

[flecc]

The pedelec sensing varies quite a lot, basically, just look behind the chainwheel to see if anything is attached. Often it's a disc with tiny magnets in it, the disc mounted on the bottom bracket spindle and having a sensor reading from it. That disc can sometimes be fixed to the chainwheel which adds complications in swapping things over.

This fuzzy extract from a photo of another make, viewed under the bottom bracket, shows the black disc behind the chainring with it's light coloured magnets showing, the sensor and it's cable in front:



However, your bike may have other arrangements, and hopefully a Windsor/Salisbury owner will be able to advise on that.
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[nin26]

Oh dear - like this you mean .....

It doesn't look like it was ever supposed to come off either.

 

[flecc]

Yes it looks like that's it. That could be rather difficult to connect to the spider centre that's needed for a larger chainring.

However, cheating is always possible, and I remember A to B doing just that years ago on an early Powabyke where the same problem cropped up.

The answer is to by a 44 tooth chainring with the same number of "spokes" (arms) as the one that's on, usually it's 4 or 5.

Then the chainring is held concentric against the old one on the outside, holes drilled and 4/5 bolts and nuts joining their spokes together. The normal derailleur adjustment takes care of the fractional outward shift of the chainring. Any tiny fraction off centre causing a slight eccentric variation is taken up by the rear mechanism spring arm.

You can probably visualise this ok, but meanwhile I'll dig out the A to B photo from history and post it back here.
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[flecc]

Here you are, further to my above post. The photo is a grotty B & W one from an early 2003 issue of A to B, but clear enough to see the detail, in tis case the larger chainring mounted behind the original. This was on the 5 speed Powabyke owned by editor David's brother, Peter Henshaw, and his partner Anna Finch shortly before they married.

That's what I call getting their priorities right, buy an electric bike first, then organise getting married:


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[nin26]

Ha - very clever! I'll have to show this to my dad - he used to be an engineer and could proabably do a very good job of getting the large chainwheel on nice and central.

Excellent - now I just need a couple of days downtime to do the work!

Thank you!

 

[flecc]

That's great. Ideal having an engineer to hand. With a 44 tooth and those rear mods the bike will be transformed into a better cycling machine.

If you haven't done so already, the standard tyres being changed to efficient ones can produce another quantum leap in cycling quality.

P.S. I didn't answer your query on the shifter. The present six speed one is practically certain to be ok, but new ones don't have to be expensive. I like twistgrip shifters, and my Shimano compatible SRAM ones cost me £9.99 each including VAT.
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[frank9755]

Interesting to see the mods that you have made, Nin.

I bought the exact same seat post for my wife's Windsor, as the fitted one is a bit on the short side.

I also considered the gear modification as I felt it could do with an extra gear at either end, but gave up when it started to look too complicated, and I started to worry that I might not be able to get the freewheel off the bike, as they can be very tight! I didn't think of the chainwheel idea - that is clever!

I'm sure you'll end up with bike that is pleasant to ride and still have spent less on it than many inferior alternatives. My wife's one has done well over two thousand miles now

Frank