[Closed] C456 29er

Looks to be a huge compromise 😐

Sorry, I'm a bit simple, (i'm not really) a compromise between what and what?

so this is just a standard c456 frame?
*interested*

so this is just a standard c456 frame?

Yes, a 16" I believe.

Yep, totally standard. 2.25 tyres.

I'm thinking of making up some dropouts (step dad can knock some cad drawings up) to bring the wheel back 25mm and the calliper above the frame as there won't be enough space between as it is, to give some more clearance for mud, but as it is it works well!

and the tyres are 2.25 Rocket Ron

Not quite sure I see the point? The bottom bracket will be rather high.

Apologies.. My initial comment was a bit harsh.

The compromise I was thinking was about was clearance that's all.

It looks right 🙂

I was going to build a rigid ss 29er and have everything but the frame so thought I would try this for the craic. That's all. I can't say I noticed the increase in bb height but as I said not ridden properly yet.

Agreed mud clearance is zero but I have a plan. See above.

Ill take a tape measure to a couple of purpose built 29er frames and see how the bb height differs.

Interesting though hey!?

Ill take a tape measure to a couple of purpose built 29er frames and see how the bb height differs.

I bet youll find the difference in bb height is surprisingly similar to the differences in axle centres 😆

I had that figured thanks 🙂 as a direct comparison between this frame on 26" wheels and 29" you are correct. But.

If a 29" specific frame is made in an effort to keep the bb height low then it may be lower than the 456 due to rear wheel position. On the other hand it may be the same/similar in which case a 29er specific frame offers no other advantage other than mud clearance. Make sense?

Well it certainly proves 650b wheels could work...food for thought

[i]<wanders off to shed to dig out unbuilt c456>[/i]

A 29er specific frame would usually have a lower bb height comparative to the wheel axels. It would also have different angles to compensate for the larger wheel, and the fork rake and trail I think would also be different. They tend to have a curved seattube as well so the chainstays aren't to long.

How much difference that all adds up to in reality I couldn't actually say.

I think that the 456 would normally run a longer fork, so the bb height to the ground may not be that different, but I can imagine it might feel rather on top, of the wheels, rather than centred between them (not sure I explained that very well).

On the other hand it may be the same/similar in which case a 29er specific frame offers no other advantage other than mud clearance. Make sense?

It will be lower, ie comparable to a frame designed for 26" wheels with 26" wheels in it.

Look at some pics of 29ers you'll see the axles are notably higher than the BB, ie the chainstays slope upwards from BB to rear axle. On your 456 they are near horizontal.

I think the mud clearance is no biggie, put a 2.0 mud tyre in when you need it. The question is if you care about the COG being 40mm higher. You might.

I guess pedal strikes won't be a problem.

@nuke, a friend runs 650b in a C456 very happily, with rigid forks tho he thinks 26" Fox boingers would work.

Also standover has also gone up by 40mm-ish. But that's only an issue if you care about it.

Yep, makes sense.

Good to know matt.

[i]<wanders back to shed to find Fox talas forks>[/i]

(Caveat. I have been drinking)

I didn't know that worked. I have heard 650b fits but didn't know we had gone so big on tyre clearance that 29ers fitted.

BB will be way high unless of course like you have you fit a very short fork. In which case BB will still be high but head angle quite steep.

I will run the numbers to see what they come out at out of interest when I get home. In Amsterdam right now.

stick a crossmark on that and clearance would be much better, would make a sweet 69er 😀

The chainstays must have been mentally long for a 26" bike.

I'm going to do some working out (drawing pins and strips of card) to try and regain the head angle with different drop outs, but I'm no engineer (unless challenged in a bike shop) so might just make it fit better and not try to be too clever!

Rocket dog, funny you should say that
[IMG] [/IMG]

fixes the head angle?

It's a shame the rear swap out bolt is where it is. If it was a bit further forward then it would be easier to make a 650b swapout (or a 29er one) as you could just go straight up to stop the BB height increase without lengthening the chainstay.

I'm going to have to try a 29er wheel in mine now as running Smorgasbord tyres on my scandal which are pretty big.

Hopefully brant will come back with some figures on the angles and where the axle needs to go. Would like to see how it works with an angleset as I've been thinking of getting one.

zerocool - Member
The chainstays must have been mentally long for a 26" bike.
POSTED 18 MINUTES AGO # REPORT-POST

A whopping 425mm. Which give balance up and down.

Good work Happyrider! Get some dropouts made that move the axle up as much as poss without going back any more than you need to. Do it now!

And Brant, when can I have a proper C456 29er (with 425mm chainstays)? I'm waiting...

Very interesting.

So, hoping Brant re-visits this thread...
Do we reckon this would work on a Whippet too?, or are the chain stays dramatically different from the 456? I know people have had success with 650b wheels. If a set of swapouts, say plus 15mm in length would convert an existing 26 into a 29, it would make an great aftermarket upgrade (I know it goes against the business of selling new frames, but bear in mind On One don't do a 456 29er and the Lurcher and Dirty Harry run a 100mm fork).
I have a whippet and some rigid forks - I don't have access to some 29er wheels, but i'm almost tempted to buy a cheap set just to try it! Also, with the type of riding I use it for I usually use smaller tyres? (ie. Small Block 8s, etc)

Works as in "fits" or works as in "rides well"?

If you think raising the BB 1.5in is a good plan, then sure.

And indeed for some situations higher BB's can be quite fun. But generally, no.

So I've had an offer up of the wheel without the drop outs on and it will move up about 23mm which will only lower the bb a little but gives plenty of clearance for the wheel.

Interesting experiment and may be awful to ride but then may be just fine for what I ride.

I'm assuming head angle is a theoretical ideal given a fully extended fork? Meaning once sag is taken into account the head angle is steeper anyway?

So. If I measure the headangle with me sitting on it with a 140mm fork and associated sag and then see what the difference is with the 29er wheels and a rigid fork (With the rear wheel 23mm higher) it will be a more accurate relationship for the geometry difference.

Sorry I'm not very busy at work and may well be thinking too much with no real knowledge...

A couple of problems with moving the wheel up are:

Getting the wheel into the drop out - might need a rear slot which is a pain to get the wheel in and out compared to vertical.

The derailleur might hit the chainstay as that too will have to move up.

Extending the wheel back will change the loading on the swapout mounts and turn the rear bolt into a pivot changing a vertical wheel loading into a downwards force on the front bolt and the rear bolt will take more vertical load. Currently the drop out location is between the two bolts. Of course most of the load is taken by the friction between the plate and the frame though so how much these changes actually matter is unknown and in real life the wheel also gets loads rewards due to hitting obstacles.

I'm assuming head angle is a theoretical ideal given a fully extended fork? Meaning once sag is taken into account the head angle is steeper anyway?

No I think geometry charts are usually for a sagged fork.

ps what about a 650b in the back instead?

understood. the point I am going to move the axle to is going to be at the rear bolt of the existing dropout. Then I can use a bolt through axle to secure it. This way it will eliminate any issues with forces acting on existing bolts and locations of.

I'm going to make new dropouts with a slot to accommodate the wheel (I realise I will have to slide the bolt through in and out to get the wheel in and out). To ensure the mech hanger is in the same place relative to the wheel and the caliper mount I am going to have it drawn up in CAD so that's no worries.

Although it should be fairly simple by tracing the existing dropouts on a couple of bits of paper and moving the center points relative to each other if that makes sense?

If anyone is interested...
Having eyed up the Whippet this morning, I don’t think a similar experiment would work. With 100mm forks, the BB is 20mm lower than my Blue Pig with 140 forks and the type of riding I do on it (XC mile munching) I don’t think the BB height would be too daft with fairly short a/c rigid forks.
Unfortunately, it doesn’t look like there would be enough clearance on the seat stays. It may work with CX tyres on 29er rims, but reducing the tyres kind of defeats the object of bigger wheels.
Another problem is the significantly steeper head angle to the C456. I fear the bigger front wheel would be quite close to cashing with your feet whilst using flat pedals.
Oh well.

Do you mean use the existing rearward bolt hole as the dropout/axle location? Or do you mean the new dropout would sit directly under the rearward bolt?

Either way it's an interesting experiment.

I was wondering if you could make a dropout that would move the axle above the existing seatstay. That might give you geo closer to the ideal but I'm sure it would do all sorts of nasty things to the forces acting on the frame/brakes, etc. You'd also have to run it SS and you'd probably end up with the chain rubbing on the chainstay. And it would look awful. But what the heck

I'd heard that 650b wheels are no problem on both c456 and whippet, didn't realise that 29ers could fit too!

I mean the rear bolt hole would be the location for the axle. Then effectively rotate the caliper side location around to above the seat stay and the hanger to the correct place and whack a bolt through errr through and it should all fit.

It means the wheel goes back 5mm or so but that's unavoidable.

Won't make a huge diff to BB height but should be interesting. Get to it young man!