Cotic is adding mullet build options to its droplink full suspension bikes. As well as getting a smaller rear wheel, you’ll also get an angleset fitte …

By stwhannah

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Cotic Bikes Release Mullet Option

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It’s an interesting one – I’m thinking 29er is something I want to try next year but I’m not wildly tall.

None of the ‘proper’ mullet bike frames seem to be available as frame only at a sensible sort of price (at the sort of travel I like – 130mm rear / 140mm front). Other than the Saracen Arial where the medium has a huge reach of 480mm which I know is too long for me to be comfortable on but the small has a very very short seat tube – plus who actually needs / wants Super Boost?

Picking up a ‘normal’ 29er frame (e.g Bird Aether 9 / Sonder Evol) and then just fitting a slackset to make it steeper / lift the bb sounds too simple to adjust for the smaller back wheel. But if it works it’s an interesting option.

It’s an interesting one – I’m thinking 29er is something I want to try next year but I’m not wildly tall.

You don’t have to be tall, I’m 5’9″ (honest), and have been riding 29ers for a good few years. Admittedly hardtails, but they’re great. I’m not a jumpy rider, more wheels on the ground (basically because I’m fat and shit at jumping) but I just love the feel of 29ers. I’ve just bought my first 29er full suss, Nukeproof Reactor, delivered this morning so haven’t ridden it yet but I’m well excited!!!!

just fitting a slackset to make it steeper / lift the bb sounds too simple to adjust for the smaller back wheel

That is what I’d have thought but according to Cotic’s chart the BB is only 4mm (still potentially significant) lower on the mullet. I’d have guessed at more.

Really I thought mullets were a bit of a stop gap while the whole world went 29, I’d suggest trying the 29er before messing with mullets

ads678 Full Member
You don’t have to be tall

This. My wife is 5’6.5″ (the .5 is important apparently) and has been riding a small Jeht since March. She absolutely loves it and I don’t think she’s ever mentioned tyre/arse interaction. That includes riding some reasonably steep stuff around the Tweed Valley a couple of times this year.

I’ve owned a couple of mulleted bikes and suffer from short leg syndrome.

Yes, they do help a bit with less tyre-on-bum action – but the really noticeable benefit is the more natural and intuitive way they corner.

But you can’t really work out what’s best for you from forums or reviews, you have to try different things and see what you prefer IRL.

I stuck a 27.5 2.8 rear wheel into my FlareMax. No Angle set but TBH I am not sure I would have noticed the 1 degree.
I did notice a lot more pedal strikes
And I just hated the way it rode – prefer the 29er set up

I did notice a lot more pedal strikes

I think that is the point of the angleset, it raises the BB

whats not called out is the significantly slacker seat angle. 2.5 deg slacker on the small. Their geo charts are wrong.

How did you arrive at 2.5° ?

@kelvin You’ve dropped the rear of the frame by 19mm and raised the front by 8mm (according to the stack). reach + chainstay on a small is 884mm. I make that you’ve rotated the entire bike backwards by ~2.5 deg, which should have the exact same effect on the seat angle.

I think that is the point of the angleset, it raises the BB

yes, obviously ….

Always felt like if you can put a 650b wheel in a 29er and have it work, it probably wasn’t a very good 29er- if the manufacturer says the BB can be lowered and it still works, then why isn’t the BB already at that height for 29er mode? But the numbers look sensible here…

For myself I wouldn’t want a 2.8 in a bike like this, good fun in a hardtail but I’d rather have a normal tyre. Getting a tough enough and grippy enough rear to do the job of, say, a DD DHR2 2.4 has big downsides. But going down to a 2.4 or 2.5 loses you height of course.

joebristol
Full Member

It’s an interesting one – I’m thinking 29er is something I want to try next year but I’m not wildly tall.

Katy Winton raced a Slash 29 for ages and she’s about 29 inches tall. Mind you she’s on a mullet now.

5lab

@kelvin You’ve dropped the rear of the frame by 19mm and raised the front by 8mm (according to the stack). reach + chainstay on a small is 884mm. I make that you’ve rotated the entire bike backwards by ~2.5 deg, which should have the exact same effect on the seat angle.

I don’t think you can’t take the full 19mm at the top of the head tube. I think you have to take this dimension proportionally to the wheelbase.
ie 19 * 884 / 1,218.5 = 13.8mm

Then, following through the rest of your calculation:
sin-1 ((13.8 + 8) / 884) = 1.4° slacker at the seat tube

This means that the “Actual Seat Angle (at 815mm BB-saddle height)” for the Mullet should be 74.1° (rather than the claimed 75.0°).

Nice bikes, but where is that trail in the pic of the descent with the chain rail?

Somewhere in the Alps with this guiding company https://www.instagram.com/p/CWGKPnaJdTm/

I don’t think you can’t take the full 19mm at the top of the head tube. I think you have to take this dimension proportionally to the wheelbase.
ie 19 * 884 / 1,218.5 = 13.8mm

Then, following through the rest of your calculation:
sin-1 ((13.8 + 8) / 884) = 1.4° slacker at the seat tube

This means that the “Actual Seat Angle (at 815mm BB-saddle height)” for the Mullet should be 74.1° (rather than the claimed 75.0°).

Thinking about it some more, I don’t think the stack measurements can be quite right…

Without the angleset the bike would slacken by ~0.9 degrees. Using a 1 degree angleset to compensate would mean that the stack should be almost unchanged (certainly much less than 8mm).

Without the angleset the bike would slacken by ~0.9 degrees. Using a 1 degree angleset to compensate would mean that the stack should be almost unchanged (certainly much less than 8mm).

I think I agree with that, but if its the case, but if it is then they’re getting a lot more bbb drop than they claim. no change at the front of the frame and the rear of the frame by 19mm you’ve lowered the bb by approx 9mm. Perhaps the angleset has a much taller bottom cup which adds to things (or a taller top cap which would add to the ‘stack’, depending on exactly how you measure it, but wouldn’t change the angles)

Assuming the stack is below the headtube, it would affect the angles based on ‘headtube to bb’ because that’s where you measure the stack at. However I did screw up as stack is the relative height of headtube to bb (not headtube to floor), so its affected by lowering the bb as much as raising the head angle.

so, if we know the reach and stack (for an identical frame) we should be able to identify how far its rotated back. but in this case, it seems the details are somewhat made up, but basically if you keep the headtube of a bike in the same place (by adjusting the fork angle) and drop the rear axle by 19mm, you’ll get a 1.2(ish) deg seat tube slackening and a 9mm lower bb

@bikesandboots It’s near Flaine and Samoens, I took the picture. Except I’m this guiding company http://alpineflowmtb.com/ instead of Wayne’s https://www.chamonixmtb.com/ As you can see, the competition between us is totally cut-throat…

The stack accounts for the external top cup on the angleset. The regular headset is zero stack, so you’ll never get your stem as low on the mullet as the regular bike. The difference in effective wheel radius isn’t 19mm either, it’s less. 27.5 tyres tend to larger volume than 29 for some reason. At least they are on all the manufacturer drawing I use.

@5lab Good point about the BB dropping means the stack increases. That said, the top of the headtube ends at approximately the same height – as per my last message, and ignoring the headset having an dramatically different dimensions. This means that the seat tube would only slacken by ~0.9 degrees. Still more than claimed by Cotic, but within the range of moving the saddle forward on its rails.

The difference in effective wheel radius isn’t 19mm either

That probably accounts for the difference. Thanks Cy

What I like about this is the ability to cheaply try a mullet. Swap a back wheel and a headset and you can give it ago. If you don’t like it its 20 minutes to turn it back to a full 29er and you don’t have a mullet frame to get rid of. Also I guess you can set the bike up for the riding. Doing a loop in the Peaks then 29er. A few days up at golfie then mullet might make more sense

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The stack accounts for the external top cup on the angleset. The regular headset is zero stack, so you’ll never get your stem as low on the mullet as the regular bike. The difference in effective wheel radius isn’t 19mm either, it’s less. 27.5 tyres tend to larger volume than 29 for some reason. At least they are on all the manufacturer drawing I use.

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I’m going with Cy’s view. He has probably forgotten more about how to properly measure a bike than I know

Always an interesting and surprisingly emotive topic this one. I will throw my tuppen’orth in; I am 5’8″ and I ride a 29er Bird AM9 in ML and a mullet Geometron G1 (medium), having previously ridden a 27.5 Bird Aeris 145lt in medium.

I am averagely proportioned, but not tall, but I can ride any of the normal wheelsize combinations (never tried anything bigger than 29, but I suspect it would be a problem on the rear for me), but I do prefer the mullet for the more extreme technical riding, primarily because it gives me just a little more arse clearance. No doubt some armchair coaches will now be frothing at the mouth because my arse should never be over the back wheel, but they’re wrong. Whether I really need the extra space is debatable, no doubt I could get used to always riding a full 29er, but why not maximise my space for manouvre? Especially if it has no practical downside that I have experienced? (I certainly don’t find the 27.5 rear wheel makes riding tehnical terrain harder and the bike corners beautifully, but a direct comparison between the two bikes is unrealistic as they are set up differently.)

It is worth noting that the G1 is set up correctly to run as a mullet and has the same BB height as the AM9 – it’s also true that I have had pedal strikes on both bikes – in reality they’re a fact of life, it’s just the frequency that changes with BB height and (like anything else in MTB geometry) it’s a compromise.

I applaud Cotic for this move, it won’t be for everyone but it is good to have the option for those for whom it works.