Brompton's own tyres ..........

[Crankarm]

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I have a new Brompton Kevlar (Green) label tyre I am trying to fit to the rear wheel of my L6. Getting it on the rim is fine but inflating it so it sits evenly all the way around is proving impossible. Every time I try to slowly inflate the tyre checking the beading all the way around the rim is seating, one portion of the circumference is failing to rise out sufficiently giving the tyre an egg profile/ or flattened appearance as it is held in which is no good! The bead at this portion appears not to be able to rise up slightly onto the seating part of the internal profile of the rim. I have tried numerous times to try to lift the tyre out as I inflate but to no avail.

My conclusion is the internal diameter of the tyre is too small as 270-300 degrees of the tyre seats fine but a short part of the cirunference is of the tyre is being held in for some reason. So I suspected the tyre diameter/circumference is too small. I measured the internal diamter at 346mm at several places around the 360 degrees of the tyre. If the internal diameter had a true 349mm diameter then I believe the tyre would seat properly.

I have fitted many many many tyres and tubes over the years from Contis, Michelin, Bontrager, Specialised, Vittoria and never ONCE have I had this problem. Any one else experienced it and how did you solve it?

The cynic in me thinks that Brompton or it's manufacturer of it's tyres is trying to save every miserable Yen in trying to make the tyre with an internal diameter as small as possible which means it is so tight on the internal rim or just not large enough making it impossible to seat the tyre easily and quickly .

Advice?

Contact Brompton?

Take tyre back to bike shop?

(Old tyre was fine except that one of the bars in the wall had started to split so I needed to change it really).

TIA.

 

[Norm]

Is it the same part of the tyre that's failing to seat each time? Or the same part of the rim, possibly?

 

[Crankarm]

Is it the same part of the tyre that's failing to seat each time? Or the same part of the rim, possibly?

No, neither Norm. I just think the internal diameter of the tyre is too small. My rim hasn't suddenly grown AFAIK.

The green label kevlar Brommie tyres have changed now to black centre section with grey outer like road bike tyres, with a reflective band which visually appears to accentuate the problem. The older version of tyre were all black, no reflective band and had more grip on the outside edge. The new version is more akin to a smoother road tyre which is all well and good if you're not worried about collecting gravel rash as you manouevre it around.

 

[Norm]

I was just wondering if there was possibly a problem with that particular tyre or the rim itself which was causing issues.

 

[Crankarm]

I was just wondering if there was possibly a problem with that particular tyre or the rim itself which was causing issues.

As I say I suspect the tyre as the internal diameter only measures 346mm and 37x349mm is stamped on the tyre wall (16" x 1 3/8) . But then if I take it back, a real PITA and get another it is likely to be the same. S'pose I could fit it in the shop just to make sure before I leave. When I bought the one I'm trying to fit they bought up two thinking I wanted a pair so they have another. Just wondering it it will be any different. I shall not be paying £25 to get the LBS workshop to fit it for me as I say I don't have a problem changing tyres and tubes normally.

I believe Brompton are secretly selling us the absolute bear minimum of rubber in their tyres. I'm sure there must be a margin on tyre sizing into which a tyre size must fall to be classed as that size and the one I have is right on the lower margin. They should really be labelled as a smaller size 346mm not 349mm.

 

[Rohloff_Brompton_Rider]

is it just one particular side of the tyre? if so try to turn it around. if it doesn't work i'm sure brompton will exchange it (they did with my dodgy tyre) they sent me an email to take to the shop to say they would replace. how about trying it on the other wheel?

edit: have you tried squeezing washing up liquid onto the rim (neat)?

 

[Crankarm]

is it just one particular side of the tyre? if so try to turn it around. if it doesn't work i'm sure brompton will exchange it (they did with my dodgy tyre) they sent me an email to take to the shop to say they would replace. how about trying it on the other wheel?

edit: have you tried squeezing washing up liquid onto the rim (neat)?

I'll try smearing some on the inside of the rim although I don't want a trail of bubbles when it rains. Maybe I try a very slight smear of LM grease. Either will hopefully very much lower the friction enabling the whole bead to slip outwards onto the rim profile adjacent to the spoke nipple heads as the tyre is inflated.

Good idea, thanks Shaun.

 

[Crankarm]

I applied some neat washing up liquid (WUL) on the inside profile of the rim and beading of the tyre using a cotton wool ear bud, well two actually, I hasten to add they were clean, although should have not wasted untainted ones really.

When inflating the tyre it didn't seem to make any difference at first , but once I got it up to 85-90 psi it started very slowly to pull out. I put 100psi in which is the recommended max pressure. It seems a lot better although examining the edge of the rim all the way around with respect to the wall of the tyre, the tyre sits about 1-1.5 mm lower on the side of the wheel opposite the valve. You can at least see the very edge of the rim is now seated in the band of small close vertical lines which I guess is re-inforced and that it is not being held in creating the weird egg shape effect or that the tyre is half the height at that point for 6 inches around the rim.

Oh well I shall leave it over night to see if it settles more evenly. If not, I'll deflate it, give some more WUL smearing and re-inflate quickly. Maybe I'll do this a few times to try to stretch the beading slightly so the tyre fits better.

Jeese I never ever had so much problems with fitting a tyre. I should have thought of the WUL though. Decided not to use grease in the end least I decide to take tyre back to the shop. I figure a light smearing of grease would be harder to clean off than WUL.

Btw it took me all of 5 minutes. I did some washing up after, hence the longer gap in reporting back.

Thanks Shaun. Chapeau.

Merci bo-coops.

 

[Rohloff_Brompton_Rider]

just remember tho, can you do that on the side of the road come punture time? seems a bit off a faff. i'd be tempted to take it back. it does seem a bit tight. is this the first tyre change on that rim? if not, was the last tyre as tight?

 

[Crankarm]

Yep 1st and only tyre change. As I said above the wall started to split on the old one which stilll had plenty of tread left .

Checked it this morning and as if by magic the new tyre had more or less settled evenly around the rim. I'd left the wheel on it's side, non-drive side.

Yes a bit of a faff if one gets a puncture away from home . But I think I'll carry a little tub of grease just in case in my bag from now on.

The wheel though was a lot easier to get on and off than I thought it would be, except for the axle nuts which require a 15mm spanner, the only size missing from my tool box, so had to use an adjustable instead. But apart from that no problemos. Can't get over the tyres though. No quick tube changes with a Brompton should one puncture.

Took the opportunity to inspect the cone nut surfaces and bearings, or so I thought, but ended up taking the hub gear out, because there aren't any, all very easy. Cleaned the bearing surfaces which were dry and re-lubed them. Put back hub gear - really neat and a lot more compact than I thought it would be, axle and refitted transmission mechanism, all very simple. The axle nuts require 22mm cone spanners should anyone else wish to tackle the job. Before you disconnect the gear cable make sure the hub is in top 3rd gear ie with little tension in the cable.

Everything is back in place now and turning smoothly.

Thanks again Shaun for reminding me of the benefits of lubrication .

 

[Rohloff_Brompton_Rider]

please tell me you didn't put grease in the rear hub or bearings. this is a defo nonnonononono on a hub gear from brompton 2009

 

[rogerzilla]

Before 1980, maybe. All modern hub gears except the Rohloff Speedhub run in grease. Sturmey-Archer have a sort of gel and SRAM use a very sticky grease which smells faintly of tobacco and, although it's clear out of the tube, turns orange in contact with the air.

 

[Rohloff_Brompton_Rider]

no no no no....no grease in the bwr from brompton...no no no no no..oil only and a thin one at that

 

[Crankarm]

No, no grease on the hub itself just the bearing races for the axle end plates. It spun like a bag o'nails before I greased them. Now the wheel spins a lot more smoothly so there will be less of my energy wasted in friction. The hub itself was very clean and covered in a light oil which I did not disturb. Anyway I clearly said my Brommie is an L6 so has the Sturmey Archer hub common to the L3 and L6 circa 2002-2004 and not the BWR hub which came in later.

There was an orange congealed substance just inside the races which I took to be a sealant. There is no way it was lubricating as it had the consistency of plastic. Anyway I left it in place and dropped the races out cleaned and lightly greased them and the opposite bearing surfaces.

 

[Rohloff_Brompton_Rider]

ok fair enough missed that bit. must be different to the new one. just didn't want you to go thru that catastrophe. glad your tyre is ok. is it on perfectly now?