Do you think it's possible to adjust these caliper brakes enough to accomodate this new rim?

[John_S]

Hi All,

Following on from the post linked to below I've recently bought a new dynamo wheel for my wifes bike which is a Globe Daily bike:-

https://forum.cyclinguk.org/viewtopic.php?f=5&t=137797

I bought a dynamo wheel from Decalthlon but their website is not very expansive when it comes to produce descriptions and what I didn't realise was that the new rim width is 22mm which is wider than my wifes current rim which is 18mm.

I'm still in two minds as to whether or not to keep the new rim or whether to return it and to buy a different narrower rim becuase there's a website which advertises dynamo wheels with a 19mm rim width. Therefore I've not yet removed or cut off all the packaging from the wheel.

But whilst I'm thinking about it I've taken a look at the rim in relation to the position of the caliper brakes as they are currently positioned and I've shown a photo of this below. Now I've never owned a bike with caliper brakes before (I've only had cantilvers, V-Brakes and now disc brakes) and so I'm not used to setting these up or the adjustments that are possible.

Now I believe that these are single pivot caliper brakes and in the image below it shows the new rim (without a tyre fitted yet) and as things stand the rim fits with the brakes pads touching both sides of the rim. Do people think that it's easy enough to adjust caliper brakes enough to accomodate the width of this wider rim? If so is it a fairly straighforward job?

I'm not sure if it will tell you much more about the brakes because I'm really not sure what make & model the brakes are but I've tried to take another photo of the brakes and this is the photo you can see with a wheel with a tyre fitted and this is the original wheel, 18mm wide, and tyre, 700x28, that came with the bike.

As a side note my wife doesn't want all of the lights etc on the bike in the summer so as a twice a year job I'll take the lights and dynamo wheel off the bike and put the original non dynamo wheel back on. Then when the nights are drawing in again I'll put the dynamo wheel and lights back on again. Now I know that it isn't necessary to take the dynamo lights and wheel off in the summer but she didn't want them on all year around and so I'll take those opportuniteies just to give tge bike a really good clean and service where necessary which is no bad thing. But I just need to know if it's going to be realitively easy to adjust the caliper brakes to the differernt rim widths or if it's going to be a pain in which case I might just have to buy a different narrower wheel as close in size to her current 18mm rim as I can.

Thanks for any thoughts and advice!

John

[pwa]

If you undo the nut holding the cable the brakes will open wider.Then get a new cable and install it with the brake blocks a few mm away from the rim. Unless I'm missing something it should work okay.

[gxaustin]

I agree with PWA.
I've just fitted wider wheels on my bike and I just needed to slacken the cable a touch.

[Brucey]

your caliper brake is a dual pivot brake. I think it ought to be possible to make it work with that rim.

cheers

[John_S]

Hi pwa, gxaustin & Brucey,

Many thans for your replies indicating that I should be able to make this work.

Hi pwa, in your message you mention getting a new brake cable and should I do that each time I do this job? As I mentioned I plan on swapping the dynamo wheel and the non dynamo wheel over twice per year once when the days are long enough and another time when the nights are drawing in again. I guess that regularly fitting a new brake cable is no bad thing and they're not terribly expensive. But just for now am I okay just to slacken the cable off via the nut holding the cable and as long as the brakes work alright when I re-tighten the cable then that's okay for now?

Hi gxaustin, thanks for letting me know that you've done something similar recently and you got it to work.

Hi Brucey, thanks for your message and for letting me know that these are dual pivot brakes and I'm definitely showing my lack of knowledge of caliper brakes!

Thanks all,

John

[Brucey]

to make enough room for the wider rim it looks like the cable will need to be pulled through the pinch bolt, such that the part of the cable that was held by the pinch bolt is then part of the cable that sees the main load. This is just fine if the cable has not been damaged by being pinched, but sub-optimal if it isn't.

Brake cables are often damaged by pinch bolts; even one broken strand will inevitably lead to more, even if it is not going to immediately break when the brake is used.

cheers

[elPedro666]

Agree it should be no problem, and you'll likely only have to replace the cable when moving to the wider rim: moving back to the narrower one you'll be shortening the cable so clamping a fresh section, with the potentially compromised area now being after the clamp. So once a year at most, which is probably no bad thing anyway!

As a minor tangent, running the lights year-round might be worth consideration; I often find the extra visibility on even a slightly overcast day to be helpful.

I'm a trendy consumer. Just look at my CLT-L09 using hovercraft full of eels.

[John_S]

Hi Brucey,

Many thanks for message and it sounds like I should have a brake cable to hand before I tackle this job. I haven't got one at the moment but I'll try to get my hands on one from the LBS if they've got some available.

Hi elPedro666,

Thanks for your message and that's a good point re: moving between the lengthening and shortening of the brake cable and making this a once a year job to replace the cable sounds better than having to do it twice and so I'm happy with this. Re: running lights all year around I actually do that on my bike on which I commute on all year round (well I do under normal circumstances anyway but not right now) whereby my dynamo lights are fitted and on all year around and I don't think that it does any harm. However my wife just wants the lights on when it's darker and she only uses her bike to pop short distances to the station or to pop into town so hopefully it'll be fine. And if changing between the two set ups means that I give it a good clean and a brake cable change once per year then that's no bad thing really.

Thanks,

John

[slowster]

Unless I've missed it no one else has suggested this, so maybe it's me that is missing something obvious and this won't work (in which case I hope someone will correct me), but...

Your caliper has an adjuster which can remove several mm of slack from the cable. On its own I suspect that might be enough to cope with the difference between the two rim sizes.

However, the adjuster is intended to allow the cable to be tightened as the brake pads gradually wear. So you would probably lose that functionality if the complete range of adjustment is used up to cope with the change of rim width. A solution to that might be to fit an inline brake cable adjuster to provide extra adjustment.

It might also help to run two sets of brake pads, i.e. use new/newer pads with the narrower rims, and thinner worn pads with the wider rims. This should reduce the amount of cable adjustment required using the cable adjuster when changing from wide to narrow rims and back.

[elPedro666]

In-line adjuster is a great shout, I bet it would take up just enough slack to work! Just had a quick search and Jagwire or Shimano seem to have the greatest range, although this bargain one looks promising too. Apologies if this is patronising, but just make sure you buy the correct diameter: brake cable is generally 5mm, gear 4mm.


https://www.wiggle.co.uk/lifeline-cable ... gEQAvD_BwE

I'm a trendy consumer. Just look at my CLT-L09 using hovercraft full of eels.

[John_S]

Hi slowster & elPedro666,

Many thanks for your recommendation in respect of using a barrel adjuster and I'll giev that a try.

THanks for pointing me in the direction of the bargain LifeLine Cable Stop Barrel Adjuster for £2.49 but when I read further down to see the producet description it said "Inline Adjuster Compatible with 4mm cable outer' and I think that above it was said to be careful with cable sizes with 4mm being for gear cable and 5mm for brake cable. Therefore I'm assuming that this barrel adjuster is for gear cable and so I looked for a different one and I've ended up buying a Shimano one bieng the Shimano SM-CB70 brake cable adjuster (link below) and so hopefully this will do the job:-

https://www.sjscycles.co.uk/cables/shimano-smcb70-inline-brake-cable-adjusters-pair-smcb70/

Plus I've ordered some new brake blocks so that the old ones can be used with the wider rim and the new brake blocks can be used with the older narrower rim.

In terms of fitting a barrel adjuster although this video shows the fitting of a barrel adjuster for a gear cable will it be much the same process / principle to fit a barrel adjuster for a brake cable?

https://youtu.be/2zUhwdXj7wc

Thanks for all of the tips.

John

[slowster]

In terms of fitting a barrel adjuster although this video shows the fitting of a barrel adjuster for a gear cable will it be much the same process / principle to fit a barrel adjuster for a brake cable?

I've only needed to fit an inline cable adjuster once, but I think RJ The Bike Guy's videos are generally very good. When I installed one, I was concerned that I was creating a point where rainwater might get inside the cable, so I did try to position the adjuster at a point on the cable where I thought it was a bit less exposed.

You will almost certainly still need to fit a new inner cable, so make sure that you do NOT insert the new inner and then cut the outer (I know its obvious, but we all do daft things occasionally). In fact I would cut the outer with the old inner cable in place, because that can help to give a clean cut and prevent the outer being crushed by the cutters.

Something else to be aware of is that as the pads on dual pivot brakes wear, the asymmetric position of the pivots will gradually result in one pad contacting the rim lower down and the other pad higher up. I think that using newer/less worn blocks with the narrow rims and vice versa should help, but if the braking surfaces are narrow and depending upon any slight differences in their respective heights, you might similarly find that you need to adjust the pad heights when changing the wheels, but that is something I would be prepared to put up with.

[freeflow]

Depending on how heavily your wife uses her brakes another option may be to fit slimmer brake pads.

[elPedro666]

So, next question: what kind of brake cable do you require, flat bar/mtb barrel style, or drop bar/road pear type? I've got a good stash of the former and would be happy to send a few to keep your good lady well supplied!

I'm a trendy consumer. Just look at my CLT-L09 using hovercraft full of eels.

[John_S]

Hi slowster,

Thanks for your message and I'm all for getting advice about avoiding doing the daft things because I've done plenty of those in my time! Also thanks for the tips about brake pad positioning and I've adjusted V Brakes before and have checked the pad position on the rim and so hopefully that job on these caliper brakes won't be too much different and thanks for the advice to check this.

Hi freeflow, yes that's a good point and I have orderd some new brake pads and so I'll look at how think or slim they are when they arrive put perhas I should have considered that before ordering nw brake pads but it's not always easy to spot that information.

Hi elPedro666,

Thanks for your message and that's really kind of you to offer in respect of brake cables it really is! When I ordered the barel adjuster I've actually orderd a couple of brake cables as well (I didn't want to order too many just in case I've not got the right thing) and so hopefully I'll have what I need for the job. But thanks very much for the offer which is really nice of you!

Cheers,

John