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  • 26 to 69 conversions…what is “trail”? And what fork?
  • Farticus
    Full Member

    As my Ti456 is now forced into commuter service, the challenging towpaths of London don’t need Pikes for too many sections.

    Luckily I have a set of Pace RC31s to swap over so the cunning plan is to use these. I’ll need to a new front wheel, so need to get it right. I see lots of talk about trail and offset but have no idea what these things mean. So, will RC31s work or are there other choices that’d work better?

    Ta.

    Posted 15 years ago
    TandemJeremy
    Free Member

    Trail – Imagine a line down the centre of the steering head – the line the steerer is on – draw that down to the floor. Then drop a vertical from the wheel spindle to the floor. the second line will be behind the first – that is trail. the more trail the greater the self centring action of the steering and the greater the stability.

    Offset – the amount the spindle is infront of the line of the steerer at spindle height

    I think this picture is slightly misleading calling fork rake the same as offset – allows for confusing between steering rake and fork rake but many cycle builders use this. In motorcycling rake is only used to refer to the steering rake

    Posted 15 years ago
    Farticus
    Full Member

    Thanks TJ.

    No idea how head angle, trail and rake interact, mind. Anyone out there care to explain & offer an opinion on RC31s doing the job?

    Posted 15 years ago
    WorldClassAccident
    Free Member

    Not sure about this trail and rake stuff but TJ sounds right. I have stuck a 26″ wheel on the back of an inbred 29er and also a 29″ wheel on the front of a 26″ bike.

    In the first case the bike felt faster to speed up and more stable, less like riding a gate.

    In the second case the bike rode smoother and faster over the buts.

    Bigger front wheels seem to make things faster, smoother and less twitchy steering but harder to wiggle through trees.

    Posted 15 years ago
    STATO
    Free Member

    I just swapped my front end for a RC31 and 29″ front wheel. The previous fork was 470~mm long (with sag) and the RC31 is 440mm, so addeded to the 30~mm of the bigger wheel the front end hanst lifted at all. The handling feels almost the same, maybe a little heavier (not noticable when riding really) but thats more down to the heavier weight of the bigger wheel.

    IMG_0660
    yummy :0)

    Posted 15 years ago
    Farticus
    Full Member

    Right, time to stop prevaricating. Time to get a wheel sorted.

    Thanks all.

    Posted 15 years ago
    WorldClassAccident
    Free Member

    Before you stop prevaricating, have you considered a 67er?

    Great for gentle off road like toepaths, fast on road and pi55es off purists. 29er wheel with cx35 tyre

    Posted 15 years ago
    miketually
    Free Member

    If I had a front 29er wheel which took a disc rotor, my Inbred would be a 69er.

    Posted 15 years ago
    WorldClassAccident
    Free Member

    mike – want to buy one? As pictured

    Posted 15 years ago
    Farticus
    Full Member

    WCA – yes, I’ve even considered seeing if I could squeeze a smaller tyred 29er rear wheel in & making it a 29er! But I do like running fat tyres (2.4″ Vredestein Killer Bees).

    Posted 15 years ago
    WorldClassAccident
    Free Member

    Fat tyres on a commuter?

    A bit draggy aren’t they? The cx tyre is V fast in dry hardpack or frozen Swinley Forest

    Posted 15 years ago
    Farticus
    Full Member

    A bit, but I had some of the Schwalbe Marathon puncture proof jobs on before. They weighed >1kg each and were so thick it was like having wooden wheels. Plus zero grip from the front. So, I switched to the Killer Bee which is pretty quick, and I can still do any steps etc. I meet.

    Posted 15 years ago
    TandemJeremy
    Free Member

    all other things being equal if you put a bigger front wheel in you alter the steering angle to a shallower angle ( nearer the horizontal) as it lifts the front of the bike. This would increase trail as it moves the line thru the steering axis further forward. So to retain the same trail you need a fork with a bigger offset – hence 29r forks have a bigger offset. whether this actually damages handling is a case of suck it and see. the bigger wheel will slow handling anyway.

    Posted 15 years ago
    firestarter
    Free Member

    my old inbred with big wheel and rc31 forks worked pretty well

    Posted 15 years ago
    WorldClassAccident
    Free Member

    The best option is go for a frame custom designed for a big front wheel. Riding the bastardised 29er On-One was enough to convince me to buy this custom Ti Carver

    Posted 15 years ago
    firestarter
    Free Member

    yeah i went from the inbred to 3 diferent 29ers and back on 26 wheels now. i think if i were to get a new bike it would be a 69er. funnily enough ive just been looking for trev the uk importers site (if he still did it) for a nosey 😉

    Posted 15 years ago
    WorldClassAccident
    Free Member

    Trev is a top bloke. He has deal quickly and in my view correctly with any issues I have had. Email me from the http://www.bigbikebash.co.uk/ site and I will send some details.

    Posted 15 years ago
    firestarter
    Free Member

    yeah hes sound i met him at ssuk other year, i was only gonna have a nose at the prices as not sure what im upto yet 😉 nice use of the link again for the bbb tho 😉

    Posted 15 years ago
    WorldClassAccident
    Free Member

    Oh, I didn’t notice the link. When you come down (you have bought a ticket haven’t you?) you can have a test on mine if you like.

    Posted 15 years ago
    firestarter
    Free Member

    too far for me im afraid 🙂

    Posted 15 years ago
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