[Closed] Trimming side knobs off a tyre for clearance?

No.

Side knobs on my slaughter are all the keeps the back end from sliding out on greasy flat corners. I'd far rather have a smaller tyre and a bit of grip than vice versa.

What nobeer said, basically.  I wouldn't forgo decently grippy side knobs just for a larger tyre either.

larger tyre = lower pressure tho.

But if you're at the point of trimming a few mm of knob off, you're probaby struggling with clearance even after doing so.

Try it and see?

My thinking was along cynic-al's lines -- lower pressure would make up for the lack of side knobs as far as grip goes, and it'd also give the benefit of getting me over rocky ground more smoothly.

Certainly if I had suspension I can imagine the extra 0.25" of tyre volume wouldn't be worth the lack of knobs... But on a rigid bike it means a lot.

In terms of clearance, I'm sure it will ride OK with a 2.6 without a trim, but a minor buckle or a bit of mud would likely cause issues straight away and I'm a cautious type with this kind of thing.

Basically, I want a 650b x 2.6 Thunder Burt without the fragile sidewalls, but it doesn't exist...

lower pressure would make up for the lack of side knobs as far as grip goes

In good conditions, yes. for the other 11.5 months of the year, no. 🙂

the whole reason the Rock Razor is such a great tyre is the side knobs!! So no.

I'm a fair weather cyclist 🙂 And a seeker of the fast drying bits in less than fair weather... Or I wait for fresh snow and then I definitely want the volume 🙂

Oh, and I've also assumed that this year's summer is the norm and am acting accordingly 🙂

Would a trimmed Nobby Nic would be any better of a solution? I'd likely only have to trim alternate knobs to get the extra 3-4mm clearance I need given the tread pattern. Though I'd loose the fast-rolling of the Rock Razor.

Looking at my current clearance, it's really the side-knobs where things get tight. The tyre carcass is OK.

(this isn't my bike btw)

I've done this, it was fine. Obviously I'd have preferred to keep the knobs but it was a case of cut them off or have the wheel saw through the frame with gritty mud.

OK, cool, doesn't sound much of a dilemma put that way, though I still have the option of not buying such a big tyre of course...

To those pointing out the loss of grip, it's worth mentioning that you are talking to someone who is planning on running a Rock Razor through the winter 🙂

But I take the point that on the RR the side knobs are perhaps even more crucial. In which case maybe a Nobby Nic is the way to go.

Only if you have some old tyres in the basement which you like to use.

In the case you plan to buy new tyres: no - wouldn't do it.

I love the side knobs too much ...

To those pointing out the loss of grip, it’s worth mentioning that you are talking to someone who is planning on running a Rock Razor through the winter

All the more need for those side knobs then. It's worth mentioning I'll be on the aforementioned slaughter all winter...

My thinking was along cynic-al’s lines — lower pressure would make up for the lack of side knobs as far as grip goes, and it’d also give the benefit of getting me over rocky ground more smoothly.

Silly question - how much lower are you thinking you'll run them? Obviously my own habits aren't yours but there's about 10psi difference between the 2" winter tyre i run with the flimsy casing and the 2.35 with a flimsy case. There's maybe 5psi between that and the decent casing 2.35 and zero between that and the 2.5. 35/25/20ish)

All the more need for those side knobs then.

Yep, I see that logic.

Ah, and I didn't realise the Slaughter's are basically the same as Rock Razors.

Urggg, I really hope this doesn't result in me deciding yet again that I need a new frame... I should at least try and squeeze something in there first. In fact, a WTB Trailblazer may even fit, given the tread pattern

I would guess I would go from the current just over 20psi to just under, not sure.

At the moment, I run something like 21-22 in the back with a 2.35psi Rock Razor 650b, and a bit under 15psi in the front with a 2.6 Nobby Nic 29er. I don't trust the gauge on my pump though.

I've done it with a 29 x 2.0 tyre in a 27.5 frame. I use it for commuting and a quick off-road loop before or after work in dry weather. When the tyre wears out, I'll fit something a bit smaller. It seems to work fine, but not something I would recommend as regular practice.

If you're trimming of the side knobs off a Rock Razor then it's the wrong tyre to start with.

Something in the same region but with weedy side knobs (and much cheaper) would be the WTB Trail Boss, which can be got in a 2.4", so very close to a RR once you've taken the knobs off.

I heard that inverse semi-slicks are going to be the next big thing - fact

I heard that inverse semi-slicks are going to be the next big thing – fact

For those that like the twin challenge of high rolling resistance and petrifying cornering

For those that like the twin challenge of high rolling resistance and petrifying cornering

😀

Sounds like a right effort of a job! Is there an easy way to trim knobs?

Is there an easy way to trim knobs?

It can be done with an angle grinder. I can't findthe video on YouTube at the minute though

I once made a pair of homebrew spiked tyres. It took a long time. A really really unreasonably long time.

They worked OK, but if I hadn't needed something to keep myself occupied with it would have been truly pointless.

Cutting off side knobs might not take so long, but it's far more pointless if it's a tyre you don't yet have.

Finally, the big question! Even if it makes any sense, can I be bothered...

I figured a stanley knife would do it, but perhaps that's optimistic(?)

Otherwise, this... although I don't really want to buy a £20 tool for a potentially stupid experiment

The other option I may consider is a 26" x 2.8". Possibly have the clearance for that

They worked OK, but if I hadn’t needed something to keep myself occupied with it would have been truly pointless.

😀 I like what you did there...

Stanley knife is quick and easy.

Death created time to grow the things that it would kill

I'm going to spend mine killing a perfectly good tyre

yer aff yer heid.

I've changed my mind about this. Had a quick ride on the way to work this morning. Short trail, but with a couple of nice sweeping sections running down a ridge, makes you feel like a World Cup champ without actually needing much in the way of bike skills. I was feeling pretty good, making decent pace and then the back tyre let go when I laid the bike over and dabbed the rear brake. Managed to keep it out of the shrubbery, but left some impressive skidmarks.

Definitely do not cut the side knobs off. You will die. If you've already cut them off, glue them back on again. (Actually, I'm too cheap to buy a new tyre so I'm going to just try to remember not to lay the bike over so pretending I have wikkid ninja MTB skilz.)

Definitely do not cut the side knobs off.

I belive youre our the only person who didn’t realise this

I belive youre our the only person who didn’t realise this

I think if you go back, you'll see that opinions were mixed. Some people said definitely don't do it, others said probably don't do it. But you never know until you try, and it is pretty exciting.

Slaughter is exciting enough at this time of year! the speed you can't really wipe off on the straights means you really need those knobs on the corners.

Legend, slight hijack, N3 and Dumyat on sunday for me, you always reckoned my way around N3 was pish, what do you do again? be parking at Cambu. Ta.

Something liek a Reoon or Ikon in 2.6 that doesn't have chunky side knobs to bein with might suit.

Little update on this.

Despite the prevailing advice above, I did make my Nobby Nic a little less nobby. I trimmed just enough off the side knobs (perhaps 2mm each side) so that they are inline with the tyre carcass. This may seem trivial, but it increased the chainstay clearance from about 6mm to 8mm, which in my head is from slightly worrying to acceptable. It took about 30mins with a stanly knife, and was a mildly meditative experience.

I road the Leeds Urban Bike Park at the weekend in very poor conditions and had no mud clearance issues and zero grip issues. I'm terrible on jumps, but I do rail berms pretty fast and if grip were seriously compromised I would have known about it.

All that said, I think I think the advice against doing this from others was perfectly reasonable. For me, on a fully rigid bike where increased volume really counts, and with very nearly enough clearance for a (comfortably fitted) 2.6", the little trim was worth it. I wouldn't want to trim more off than I did. And if you're on a full suss, sticking with a 2.35/2.4" is probably best.

I can grab a pic if anyone so desires

I heard that inverse semi-slicks are going to be the next big thing – fact

For those that like the twin challenge of high rolling resistance and petrifying cornering

Bravo.