Muddymoles mountain biking in the Surrey Hills and Mole Valley

On-One Inbred 2003 geometry

Posted by Matt | January 18, 2021 | 14 comments so far

On-One Inbred geared frame from 2003
For a very long time I’ve wanted to document the geometry numbers on my original On-One Inbred which dates to 2005.

In fact, the Inbreds go back further. The clue is in the name, borrowing the famous DeKerf split rear end seatstay design for a start (just to be clear, I’m not saying that’s where the name came from!).

By 2005 when I got my original design frame they were starting to get a bit outclassed, though never declasse. Dave had exactly the same frame in 2003 and the first singlespeed versions started around 2001 albeit with marginally different sizing.

At the time, the Inbred’s built quite a cult following for being not only cheap and made out of steel but for having a long top tube and short stem (at least by the standards of the day). Does that sound familiar?

Even more surprising is that if you take the stem + Effective Top Tube numbers together, the dimension of my 16″ Inbred with 90mm stem is exactly the same distance as my modern Long, Low and Slack Bird Zero AM!

Of course, it’s the differences that are important. Back then head and seat angles didn’t get the same focus and of course, everything ran on 26″ wheels. ‘Slack’ as a concept was rarely discussed. Neither was the Wheelbase, or the Reach or BB drop. Another key figure to contrast – the handlebars – were considered wide at 660mm, whereas now I run a conservative 760mm bar on my Bird.

On-One Inbred 2003

Several subsequent models appeared – a 456 version in ‘That Blue‘, a 456 version in ‘New Blue‘, then 29ers of different flavours, including Dave’s famous ‘Desert Sand‘ version. Dave it seems probably had them all at one time or another and he wasn’t alone.

Despite that, I still have my Inbred and feel the original was best. Run it with 700mm bars for the best flex vs. control balance. Don’t expect to keep up with modern machinery.

Anyway, the figures for the original geared 2003-era frame are below, saved for posterity before even the internet forgets. It does amuse me that in many ways the numbers are similar to modern gravel bikes but with smaller wheels and a lower stack. What’s old is new and what’s new is… one day old.

On-One Inbred 2003 geometry chart

Sizes 16″ 18″ 20″
Rider height Size 16″5’6″-5’10” Size 18″5’9″-6′ 1″ Size 20″6′-6’4″
Stem suggestion Size 16″60-80mm Size 18″60-80mm Size 20″80-105mm
Effective Toptube Size 16″589 mm Size 18″602 mm Size 20″612 mm
Head Angle static Size 16″71° Size 18″71° Size 20″71°
Seat Angle Size 16″73° Size 18″73° Size 20″73°
BB Height static Size 16″302mm Size 18″302mm Size 20″302mm
Headtube Size 16″90 mm Size 18″105 mm Size 20″120 mm
Standover Size 16″716 mm Size 18″747 mm Size 20″775 mm

Seatpost size – 27.2mm (the tube is slotted at the front, to stop muck getting in)
BB Shell – 68mm (axle length of 113mm)
Seat tube size – 29.8mm seatclamp, 28.6mm front mech.
Headtube size – 1.125in (inch and an eighth)

What’s clear to me, running a 16″ frame with an over-long 90mm stem, is that the frame is just slightly too small for me, which is why it always felt like a big BMX!

Filed under Bikes in January 2021


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 14 comments on ‘On-One Inbred 2003 geometry’

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  1. Tony says:

    Did we all have Inbred back in the day (and wasnt the name some sort of Yorkshire name pun). I had a red 18″ which I geared and single speeded, even ran with the Alfine hub (passed onto Mark), although it handled pretty well for the time I never really gelled with mine and moved onto my MK2 Orange Clockwork hardtail which is still in the garage!

    The thing is compared to my 29er HT these bikes today look and are so much smaller, underwheeled especially in bigger sizes. Almost I can’t believe that they were the “best thing ever” when we had them

    • Matt says:

      26″ wheel bikes were totally underwheeled in hindsight. We just didn’t realise at the time. Context is everything.

      I think most of us had an Inbred as the cheap, sensible choice for winter biking at the very least. Those with greater means went titanium (I think Lloyd and Jez both had one), but most of them were platforms for experimentation.

      I had 3×9, singlespeed, 2×10, with regular bits, then pink bits and now green bits at different points. My pink and white singlespeed set up remains my favourite as it had 700mm pink bars in a 25.4mm diameter. Really comfy!

      Despite all the frame variations the head angle never changed much until a wild Alpine variant appeared with a 64° headangle IIRC.

      So near but so far; it was in the right ballpark but eventually frame and wheel standards moved on and the Inbred didn’t.

  2. Jez says:

    I had the summer season inbred, which was their take on bikes such as the Cotic Befe and your Bird Matt.
    Can’t say it really excited me, it was as stiff as a medieval side gate and rode like one ( probably more that I have little skill).
    They had their place though at that time, seems they haven’t moved on with the times.

    • Tony says:

      Lloyd did buy a Ti Inbred and I can confirm he still has it since he was riding on it on our Sunday ride. Albeit now converted to 1x and 700c/650b with skinny tyres for Gravel duties / Zwift riding.

    • Matt says:

      Jem, it definitely wasn’t a lack of skill on your part. It’s just people’s understanding of bike geometry has changed massively.

      As for Lloyd and his Ti Zwift bike – LOL! That’s so funny. I’ve seen it on gravel duty and it works well with the benefit of a suspension fork too.

  3. Dandy says:

    I too was a member of the Mole Inbred posse, the 456 version. Bought as a winter hardtail to avoid trashing the pivots and drive chain on the Whyte full-susser (PRST-2), it was converted to an Alfine hub and run for several years. I think it went in my emigration-forced fire sale, not sure who picked it up. I don’t miss the Slurrey Hills BGM !

  4. Elliot says:

    I remember a period where standing up Leith Hill on a Sunday half the bikes would be Inbreds. Of course that might just have been random coincidence being there same time as the Mole Inbred outing.

    My last 26er had a shockingly long 120mm stem with 660 bars and a setback post. Weirdly it felt horrible with a 90mm stem and 700 bars. It was only a large but the overall seated position was longer than the XL bikes I have now.

  5. hippy says:

    My SS has disc brakes on the chainstay and a rigid carbon fork. No idea which version/year. It came from up north via ebay with a 100mm stem but that’s now 50mm but with cut-down bars for commuting in London. It’s going to get knobbies put back on, lower gearing so I can actually climb it and wider bars.
    Thanks for the geo chart.

  6. matt fry says:

    Hi Matt
    Matt here. What happened to the 14″ size geometry? Just rebuilt mine with gears for the first time (slot drop, red, about 2012). Also got 1998 Judys on. Absolute pogo stick maniac bike. Considering trying it with gravel drops/midge bars to go camping on. Be useful to know the numbers.
    like I said.

    • Matt says:

      Hi Matt, sorry not to pick this up sooner. I got the Inbred geometry chart off Brant Richards via the Internet Archive but the year I looked at – 2003 – doesn’t mention the 14″ size.

      I have heard of people using Midge style bars, guess you just have to fine-tune with stem length. We have a rider who is using a Ti Inbred with a regular 100mm fork but flat bars, 650b wheels and 40mm gravel tyres. Seems to work for him but the fork encourages him to push the tyres more than they want to go…

  7. Jos Fliers says:

    I picked up an inbred on “marketplace” (sort of Dutch e bay) last summer. 18” frame, third hand. Half the parts provided with it. Build it up copying the geometry of a Dutch “opoe fiets” (grandma’s bike). Stem height 19 cm length 0 cm. Jones H riser bar with 2,5” extra height, generous back sweep. So is it it still a mountain bike? Probably not but we don’t have mountains anyway so who cares. And with my hand and back problems it’s the first comfortable normal bike in 25 years, have been riding recumbents all this time for this reason. With 26” wheels, but I have a pair 27,5” wheels for gravel riding and am considering a 700c front wheel mullet setup for the coming summer. It’s a dream to ride in this configuration over here, an ATB not a mountain bike but capable enough to do some XC riding on moderately steep terrain. Love it.

    • Matt says:

      Hi Jos, thanks for the comments – we have guys here who have ‘re-purposed’ their Inbreds to ATB/gravel bikes with 27.5″ wheels and narrow tyres (the bigger wheel limits the tyres that will fit).

      It seems to work well, the biggest problem is with a front suspension fork and skinny tyres you can forget the limits of the tyres if you are not careful!

      I still have my own Inbred (owned since new). I have not used it for a while as the fork needs a major service but I am keen to keen to get it working as it’s a great trail/riding along bike. We used to tackle all sorts of terrain but I probably need to get a dropper post – I can’t be bothered to continually stop to manually drop the saddle these days.

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