Mudguard heating - deforming to fit

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Vantage
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Mudguard heating - deforming to fit

Postby Vantage » 2 Feb 2019, 11:01am

I currently have 700c mudguards wrapped around 26" wheels. This hasn't been an issue until recently when I fitted 1.75" Schwalbe Marathon Winters as the clearances are ridiculously tight.
I'm having to really strain the front guard so it clears the tyre under the fork crown.
My idea is if I were to strap said mudguard to said wheel and gently heat it, would it eventually follow the curvature of the tyre and so need less bending at the fork crown?
The pic below I hope shows the issue.
15491052191813512591856018907423.jpg
Bill


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NATURAL ANKLING
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Re: Mudguard heating

Postby NATURAL ANKLING » 2 Feb 2019, 12:32pm

Hi,
Add some safety clips on the stays too.
I have tried it and still failed to get a set to stay.
Mine was black soft plastic like pvc.
You probably need to heat it to a critical temp but not with a local heat source like hot air gun.
Blistering might occur as you get there.

I am not sure that those guards are thermo plastic?
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fastpedaller
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Re: Mudguard heating

Postby fastpedaller » 2 Feb 2019, 1:43pm

bending it is like bending a piece of metal though - unless you are using a mould the plastic will go wherever it wants - there will be 'surplus' which will fold and crease (IME just where you don't want it to go)

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Mick F
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Re: Mudguard heating

Postby Mick F » 2 Feb 2019, 2:36pm

I have a thread on here for some years ago about heating a mudguard to put it so it was in line at the front.
The mudguard sort of bent to the right half an inch. Maybe poor manufacturing or poor storage. I asked the question on here.

I took a heat gun on a minor setting - hot, but not too hot - and heated the mudguard off the bike of course. I re-formed the area for under the fork crown so when re-fitted it would be straight. It worked a treat but I was very very careful.







Found the thread! :D
viewtopic.php?f=5&t=67327
Mick F. Cornwall

brynpoeth
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Re: Mudguard heating

Postby brynpoeth » 2 Feb 2019, 2:56pm

Thermoplastic might behave strangely
Wait for Brucey to come by :wink:
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Re: Mudguard heating

Postby Brucey » 2 Feb 2019, 5:13pm

often a mudguard fits better if you put a slight bend into it (eg at the fork crown or where it passes through the seat stays) and this isn't too difficult to do. But what you are talking about is resetting the curve entirely. I think this is likely to be

a) difficult to do well (ie without kinks) and/or
b) will require different radius wheel (or former) to get the shape, not the wheel you intend to use.

On the latter point the radius you want is 13-1/2" to 13-3/4". The radius you will get if you use your present wheel is likely to be fraction under 13". It is quite possible that the temperature you need to get the mudguard to move is so high it will wreck any tyre underneath. I'd suggest using an old tyre underneath (ie not one that you ever want to ride on again), if you use a tyre at all.

FWIW if you can't buy the mudguards you really want (in width/length/radius) then there is something to be said for buying some types of aluminium mudguards; often these can be reset to a different wheel size without too much difficultly.

cheers
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Vantage
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Re: Mudguard heating - deforming to fit

Postby Vantage » 2 Feb 2019, 5:47pm

That's what I was afraid of.
Best get scrimping and saving for new mudguards.
Thanks chaps.
Bill


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willcee
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Re: Mudguard heating - deforming to fit

Postby willcee » 2 Feb 2019, 6:12pm

Looks to me that those guards are very wide,and that one is a rear modded to fit.. so the edges that pass under the fork yoke are actually catching the inner sides of the fork. i have dremelled a waist marking where the clearance is needed this should allow the guard more leeway to rise.. if not enough think about resetting the metal clamp so that the metal sits outside the fork yoke not inside where it oftens butts against steel , again i have done so in the past.. the older forum will remember that Bluemels were always waisted at fork yokes.. will

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SimonCelsa
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Re: Mudguard heating - deforming to fit

Postby SimonCelsa » 3 Feb 2019, 5:43am

SPA have some mudguards on offer at the moment, basic SKS but should do the trick, tractor tyre size though!!

https://www.spacycles.co.uk/m2b0s80p387 ... -Mudguards

slowster
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Re: Mudguard heating - deforming to fit

Postby slowster » 3 Feb 2019, 9:45am

SimonCelsa wrote:SPA have some mudguards on offer at the moment, basic SKS but should do the trick, tractor tyre size though!!

https://www.spacycles.co.uk/m2b0s80p387 ... -Mudguards

The 26" 65mm Bluemels mudguard linked is only available in black from Spa. If Vantage wants to stick with silver, Spa also sell the SKS Chromoplastic mudguard in silver in the 26" 65mm size https://www.spacycles.co.uk/m2b0s80p1344/SKS-Chromoplastic-Mudguards.

However, the fork crown and/or seat stays might not be wide enough to accept a 65mm mudguard (and I imagine in the light of his experience, Vantage would like a mudguard that fits without any need for squeezing, bending or trimming), and/or Vantage might consider 65mm wider than he requires assuming that 26 x 1.75" (47mm) is the widest tyre he ever plans to use.

If so, it is possible to buy the SKS Chromoplastic and/or Bluemels mudguards in silver in 26" in the following sizes:

- 60mm Bluemels (e.g. 2nd from bottom in the list of different sizes here https://www.bike-components.de/en/SKS/Bluemels-Front-Rear-Mudguard-Set-p24393/).

- 55mm SKS Chromoplastic (e.g. https://www.tredz.co.uk/.SKS-Chromoplastic-Full-Length-Mudguards_15491.htm also available at SJS)

- 53mm Bluemels (e.g. https://www.cyclecentreuk.co.uk/m2b0s88p15452/SKS-BLUEMELS-MUDGUARD-53MM)

SKS suggest mudguard widths for given tyre sizes as per my post on this thread viewtopic.php?f=5&t=126557&p=1297714#p1297714.

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CREPELLO
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Re: Mudguard heating - deforming to fit

Postby CREPELLO » 3 Feb 2019, 1:48pm

Looking at your photo, I'd suggest cutting the guard in half at the crown would be the best way to gain the necessary clearance. Fortunately, as you have used a long rear with front of crown stays, this will aid the rigidity of this fix significantly. How you choose to re-attach the front section of the guard to the crown is up to you, but a stainless rear bridge mount would be the obvious choice. You should have one kicking around as I'm guessing you'll have bought two sets of guards to make your hybrid setup.

Alternatively, do you still have the old front guard? The crown angle bracket off that could either be re-deployed, or you could possibly use the section of this original front guard, between the crown bracket and the nearest stay bracket, as your new leading section. Re-using the section of front guard would also mean no need to re-attach the crown bracket.

cycle tramp
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Re: Mudguard heating - deforming to fit

Postby cycle tramp » 3 Feb 2019, 5:54pm

Yes, you can do this.... probably... I once reduce a set of chromoplastic mudguards designed for a 26 size wheel to cover a pair of 20 inch size wheels. Rather had using a heat gun i used boiling water* in a steel sink. Dipped the bit of the mudguard that i wanted to bend into it - at which point it became entirely floppy and then took the mudguardout and bent it around the wheel.....
...It took about 5 jugs of boiling water to finish the pair, and i had to keep go back over some of the areas of mudguard to get a better shape...
..sadly i didn't keep the bike long enough to know if I had reduced the service life of the mudguards..
...however the modified mudguards worked alot better than the original equipment, covering the 2 inch big apple tyres without rubbing them...
If you're successful please post some before and after photos :-)
(* be careful now)

Slowroad
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Re: Mudguard heating - deforming to fit

Postby Slowroad » 3 Feb 2019, 8:15pm

SKS suggest mudguard widths for given tyre sizes as per my post on this thread viewtopic.php?f=5&t=126557&p=1297714#p1297714.

SO useful! Thanks Slowster! :-)
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