WTB ST i25 Tubeless set up
Following on from my rather straight-forward efforts to set up my Hunt Trail Wide MTB wheels tubeless, it was time to look at my Bird Zero AM.
The wheelset on the Bird is brand new and unused, inherited from the Pinnacle Iroko donor bike I bought from Evans Cycles. The WTB ST i25 wheelset came fitted with inner tubes, even though both the wheels and the WTB tyres are marked as TCS – WTB’s Tubeless Compatible System. In other words WTB’s flavour of tubeless easy.
Now I really don’t like using inner tubes on my mountain bikes because you never know when they will puncture – it’s usually miles from anywhere just when you’re getting tired or cold or wanting to be somewhere else. I wasn’t going to ride the Bird off-road without first converting to tubeless.
As it turned out, I’m really glad I didn’t risk a tubed puncture with these wheels.
Getting the WTB Vigilantes off the ST i25 rims
Maybe you can guess what I’m going to say?
Yep, those Vigilante tyres REALLY did not want to come off the rim!! As in not budging AT ALL! Try as I might, I couldn’t even get the tyre bead to move away from the wheel rim, let alone shift enough to get a tyre lever under them.
The problem had to do with both the profile of the rim and the tight tolerances of the WTB 27.5×2.3 TCS Light/Fast Rolling Vigilantes. It turns out the WTB ST i25 rim has a reasonably deep central trough with small hooks on the edge between the trough and the bead. As you can imagine, it’s designed to retain the bead on the rim to maintain an air tight seal.
In addition to this, I think Evans Cycles had let the side down by using a really nasty plastic non-tubeless rim tape when setting up the bike. It was thick and so wide that it stretched right from bead to bead. With this in place, and the rim design, and the tight tyres…
…cue a very sweary hour to get one tyre off one rim! If I had been on the trail it would have required a team car rescue because there is no way anyone would have got those tyres off.
My annoyance was made all the more so because the WTB rims and tyres are intended to work together. It was really, really disappointing.
In the end, I had to lubricate the rim with my Schwalbe tubeless mounting fluid so that the fluid could lube the rim bead and tyre bead, then I gently eased a screwdriver in between the bead and the tyre. By pulling stoutly on the sidewall I managed to gradually shift a three or four inch section of tyre bead into the central channel, over the raised lip. It was incredibly difficult and I was really worried a slip of the screwdriver would damage my brand new wheels.
Having cracked the methodology, it was another 20 minutes to get the second tyre off! By that time the tyres had been wrenched and pulled in all sorts of directions.
But that wasn’t the end of the saga.
Taping the ST i25 rims
Next, taping the rims. I had purchased some of the Hunt Black Shield rim tape after seeing how smoothly it had been fitted to the Trail Wide wheels. But trying to tape the WTB rims was anything but easy, mainly because of that weird deep and hooked trough on the rim bed.
Eventually I managed to get things nicely taped, using a huge unrelenting pull on the tape to get it to sit nicely into the trough. By this stage, I was getting pretty tired and pretty fed up!
I subsequently found that WTB tacitly admit their rim profile is a pain. How do I know? Well they sell a double layer system which they claim makes it a lot easier to mount their TCS tyres tubeless – first there’s a TCS 2.0 Solid rim strip which fills the space in the trough; next, a TCS 2.0 Flex tape to seal and smooth the rim profile. Maybe they should just change the rim shape, because without this option the process was absolutely infuriating.
The thing was, after all the hassle to get to this point I still needed the tyres mounted and sealed.
Sealing the WTB Vigilante and STi25 rims with Muc Off sealant
It’s worth noting at the outset that while the 2.3 WTB Vigilantes appear to have a nice tread pattern – a pattern I have high hopes for on the trail – in this TCS Light/Fast Rolling guise there is very little support from the side walls. In contrast, the heavier duty Maxxis tyres on the Jeffsy virtually stand up on their own!
I needed a bit of help from the tyre levers to get the tyres onto the rims and then needed to press the BETO JetAir Tubeless Tyre Inflator into action again, as there was no way the tyres were going up onto the bead using the track pump alone.
After that, all that remained was to seal the deal – or rather the tyres. I’ve recently read good things about Muc Off’s Tyre Sealant and had decided to use that in the Bird’s wheels.
As a system, the Muc Off sealant is well packaged – a valve remover, scoop and small UV lamp came with the 140ml pouch that I used on each wheel. The main selling point for me was reports that it doesn’t ball up like Stans in the tyres, and the pouches are re-fillable and can be carried in a backpack. I like that idea – less waste and a handy backup too.
However, as far as sealing goes? Initially I wonder if I didn’t put enough in because I was following Muc Off’s recommendations to the letter. Try as I might I couldn’t get the damn tyres to seal, so added more sealant – eventually nearly all of one pouch into each tyre. By this stage I was all for having a proper tantrum and throwing in the towel completely.
I persevered. It took some 20 minutes and several goes at re-inflating the tyres before eventually the tyre on the first wheel started to hold air.
Small bubbles of sealant could be seen pushing through the sidewall of the Vigilante which makes me wonder if perhaps my earlier wrestling match had damaged the thin sidewalls. Fluid could also be seen around the valve – maybe the rim profile wasn’t helping either?
This experience repeated itself on the second tyre, but I’m glad to say that once the tyres decided to hold air they have continued to do so and didn’t lose a bit overnight either (nor did the Hunt/Maxxis combo by the by). I just worry the Vigilantes might cut easily from what I’ve seen so far…
So I now have a sore back from a day bent over two wheelsets and charging my BETO JetAir cannister to 150psi repeatedly. I have very sore hands from wrestling with the unforgiving WTB tyres and I have very bruised thumbs from applying the rim tape. I was so sore on Sunday morning that I missed out on a great day for riding – all this effort better be worth it!
About the author
Matt is one of the founding Molefathers of the Muddymoles, and is the designer and main administrator of the website.
Having ridden a 2007 Orange Five for many years then a 2016 YT Industries Jeffsy 29er, he now rocks a Bird Aether 9 and a Pace RC-627.
An early On-One Inbred still lurks in the back of the stable as a reminder of how things have moved on. You can even find him on road bikes - currently a 2019 Cannondale Topstone 105 SE, a much-used 2011 Specialized Secteur and very niche belt drive Trek District 1.
If you've ever wondered how we got into mountain biking and how the MuddyMoles started, well wonder no more.
There are 18 comments on ‘WTB ST i25 Tubeless set up’
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Related: Hunt Trail Wide Tubeless set up | Reviews, Wheels & Tyres | Muddymoles: Mountain biking (MTB) in the Surrey Hills and Mole Valley
Dandy says:
Eeek ! A+ for perseverance
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Posted on February 19, 2019 at 2:41 pm
Elliot says:
Wow, think those wheels and tyres would have received ‘a damn good thrashing’ for their disobedience if it were me!
Presumably with that inner rim profile the good news is it will prove difficult to burp air when you square off a corner too hard…
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Posted on February 19, 2019 at 6:34 pm
Matt says:
I was on the verge of throwing them on several occasions Elliot.
I’m hoping now the wheels are set up they won’t need too much attention and that with tubeless tape on the bead will release more easily. I don’t think there’s much chance of burping but I’m worried the thin sidewalls might cut.
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Posted on February 19, 2019 at 10:29 pm
Andrew AKAK says:
That sounds a lot like my experience of wtb tyres…and I didn’t even have that horrible lip on the rim. Just could not get them to move.
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Posted on February 19, 2019 at 8:02 pm
Matt says:
It was traumatic! I could only manage it by lubing everything and using a flat bladed screwdriver while puling from the opposite side.
The trick was to keep the tension at all times while easing the bead over 1mm at a time over a longish stretch. As soon as I managed to get about 3-4 inches moved into the trough, the tyres came off really easily.
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Posted on February 19, 2019 at 10:26 pm
Gordo says:
Gosh, one of the best bits of being a cyclist is the exercise it gives you in the fresh air. Sounds like you have had that benefit here, but without the nuisance of having to wash the mud off your bike!
Thanks, as ever, for the well written write up and I’m very pleased you triumphed
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Posted on February 20, 2019 at 11:55 am
Related: BETO JetAir Tubeless Tyre Tank and Inflator | Accessories, Reviews | Muddymoles: Mountain biking (MTB) in the Surrey Hills and Mole Valley
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Mat-S says:
I’ve just seen this- I’m interested because it doesn’t tie up with my experience of WTB rims. I’ve had Frequencies, KOMs and STs, all with the same deep channel, bead hook design, running everything from 32s to 2.5s and generally found them to be good. What I don’t have is the experience with their MTB tyres.
I think a fair bit of it may be down to the rim tape, how thick is that Hunt stuff? I’ve always used the thin stans style yellow stuff and applied it from the centre out so it conforms to the bead barb. Tyres tend to take a bit of an initial blast because of the deep rim well, but then pop into place nicely.
Talking about them as a system- I’ve seated a 40c Nano on a KOM with a decent sized hand pump, so it does work on occasion!
While the hook is tight, the actual BSD is relatively loose. A slack tyre like a Surly Knard, for example, will literally fall off a KOM. I’ve not had any problems with tubeless ready tyres though. Stans are the opposite- no hook but the BSD is oversized. WTB tyres on Crests are tight enough to take most of the tension out of the spokes (American Classic have the Stans BSD AND the WTB hook- I thought I was going to have to cut a WTB tyre off one).
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Posted on April 16, 2019 at 4:56 pm
Matt says:
Hi Matt, all I can say is the WTB i25 and 2.3 Vigilante combo was awful to get off the rims when Evans had used standard non-tubeless rim tape to set the bike up with inner tubes.
Once I had managed that the process was easy as anything – I’ve just also set up some i23 rims with WTB tyres and tubeless rim tape and they were dead easy. I think it’s the thoughtless use of standard rim tape that needs to be avoided in this instance.
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Posted on April 17, 2019 at 10:30 am
Related: Cannondale Topstone 105SE has arrived | Bikes | Muddymoles: Mountain biking (MTB) in the Surrey Hills and Mole Valley
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simon smith says:
I had same problem with Pinnacle Arkose X – lots of swearing to get original tyres off (WTB ST Light i25 TCS 27.5/650b).
I have given up trying to convert to tubeless – the deep channel in the rim does not allow tubeless tape to stick to full cross section of rim – tried all different tape widths and double taping. I have a compressor so could manage to seat tyres properly but sealant always ended up leaking from spoke holes.
I now run these with inner tubes and to be fair the WTB Sendero tyres are pretty robust so I only get a puncture about every 3 or 4 rides in the UK muddy countryside.
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Posted on January 5, 2021 at 2:17 pm
Matt says:
Hi Simon, after so much aggro with these rims I’ve now put 1200 miles on the i25s on the mountain bike. I think I would suggest using the WTB Solid Strip underneath the tubeless tape which is their suggestion. I don’t have it but would use it next time and the Vigilante tyres have been brilliant to be fair.
Another valuable lesson – the Muc Off tubeless sealant is total rubbish!
After about 400 miles I had a leak from around the valve on a very cold night which wouldn’t seal. Nearly froze solid trying to get the tyres off and a tube put in.
My brother in law on his Arkose has punctured twice with Muc Off too on WTB tyres, it never seals even with double the recommended dose. My WTB shod Cannondale was the same. You just end up looking like there’s been an explosion in a Pepto Bismal factory!
After switching back to Stans fluid for all my bikes, not had another problem and I managed 4000 miles last year.
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Posted on January 5, 2021 at 2:44 pm
simon smith says:
New tips for WTB ST Light i25 rims and WTB tyres!
Getting tyres off – put the wheel on the floor and slowly walk around the tyre putting your heel as close to the rim as you can. After 2 to 3 rounds the tyre is easier to get off the rim.
Tubeless tape – I now use gorilla tape 25mm wide – 1 layer – works a dream.
Sealant – I use Stans Race – not cheap but works. I also found squirting sealant into the value seemed to result in all the ‘bits’ not getting into the tyre. I now pour sealant into the 90% mounted tyre and then pop the final bit of tyre on.
WTB tyres – Senderos are great – highly recommed.
WTB tyres – thin side walls does result in sealant leaks initially but does seal.
I still maintain there are problems with these rims and tyres – in particular popping to tyre back on the rim requires major PSI – not possible on the trail.
Simon
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Posted on September 4, 2021 at 9:19 am
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