Frame swap - what would I need

larkim

Been on the lookout for a 19inch frame for a Spesh Hardrock to make a cheapish size improvement for son's 15.5 inch model.

Spotted this on ebay - http://www.ebay.co.uk/itm/301311998102? ... EBIDX%3AIT

the one thing I've noticed is that I presume I'd need to do something with a headset, as this one doesn't seem to have anything pressed in. I'm competent enough to swap BB, move across calipers, derailleurs etc. but never done anything around the headset.

What, in general terms, would I need to do?

Cheers!

Matt

jimothy78

First of all, check the crucial details of your son's bike against those provided on the listing, to make sure that all the parrts will swap straight over. Don't trip up over something like wheel size The one in the listing appears to be the 2011 model:
http://www.bikepedia.com/quickbike/Bike ... &Type=bike

Pressing in a headset is actually very easy, and it's probably easier to get a new one rather than mess about with removing the old one from the old frame - especially if you can find out what model the existing one is, and buy a new one the same, so you'd be getting brand new bearings, etc, but could leave the crown race on the forks unchanged, which would save the bother of removing it and installing a new one.

larkim

Yes, thats a 2011 - same as his - which is why I'm particularly interested. Identical colour scheme too.

I guess the LBS could press a headset anyway, but if that's what needs to be done at least I'd know about it in advance.

Cheers!

benpinnick

Hydro brakes likely wont fit too as the hoses will be too short, and you'll need new outers and inner gear cables, also, your forks would be a marginal as well - likely too short as a 19 will probably have a much longer headtube than a 15.5

The Rookie

Headset swap is easy, knock yours out with a hammer and screwdriver, knock it into the new frame with a hammer and block of wood, or use threaded bar to make a press if you prefer.

larkim

benpinnick wrote:

Hydro brakes likely wont fit too as the hoses will be too short, and you'll need new outers and inner gear cables, also, your forks would be a marginal as well - likely too short as a 19 will probably have a much longer headtube than a 15.5

Hydro not an issue as the bike is all cable, and that stuff is relatively cheap.

A new fork though would turn a reasonable £100 job into a £200 job, and for that I might as well sell the existing bike for £100-£150 and get a Rockrider 520 from Decathlon. It does really need new forks in any event, but I was hoping that a straightforward size increase could put that off for a year and just squeeze the last bit of value from this bike.

Does anyone know where the geometry for the 2011 Hardrocks can be found, which presumably would allow me to see whether there was a difference in the headtube length?

Thanks for the steer - perhaps saved me an uneconomical purchase!

larkim

Ignore that request - found it here:-
http://www.specialized.com/gb/gb/bikes/ ... c#geometry

Presume that with the difference in headtube "height" (100m vs 120mm) and the stack (is that relevant) of 571mm vs 590mm then a straight fork swap isn't going to work?

veronese68

larkim wrote:

Ignore that request - found it here:-
http://www.specialized.com/gb/gb/bikes/ ... c#geometry

Presume that with the difference in headtube "height" (100m vs 120mm) and the stack (is that relevant) of 571mm vs 590mm then a straight fork swap isn't going to work?

Could you remove any spacers and fit a slimmer stem?

jimothy78

^This

From the pic on the spesh website it looks like there's about 15-20mm of spacers on that bike. If your son's bike has a similar amount of spacers, then you should be ok. Worst case scenario you might need to swap the stem for something with less "stack height" (go shorter at the same time).

larkim

Cheers guys - am I right in thinking the following:-
-headtube "height" quoted by spesh is the length (excuding the pressed headset) of the headtube from top to bottom (or bottom to top, if you prefer measuring upside down)
-the "stack" referred to is the height of the headset protruding from the headtube, plus the combined height of the spacers

If so, then I need (120-100)+(590-571)mm of spacers in the current setup that could be removed (i.e 39mm) form the current arrangements to give enough space for the existing stem to be mounted on the top of the fork? (Or, as you suggest, a stem which takes up less space on the fork tube?)

Mechanically I'm feeling happy enough with this, I just want name clarification!!

Cheers!

Matt

jimothy78

larkim wrote:

Cheers guys - am I right in thinking the following:-
-headtube "height" quoted by spesh is the length (excuding the pressed headset) of the headtube from top to bottom (or bottom to top, if you prefer measuring upside down)

Yes.

-the "stack" referred to is the height of the headset protruding from the headtube, plus the combined height of the spacers

Not sure about this - usually "stack height" is a term applied to components like spacers, headsets and stems to describe how much steerer length they "consume". I've never seen "Stack" stated in this way before, but the size of it (nearly 2 feet) suggests to me that Specialized are using it it here to describe the height of the handlbars above the axle or something like that. It can't just be headset, stem and spacers etc, cos it's many times too large for that. Therefore, it's highly likely that whatever it's measuring already includes the headtube, and the difference between the figures is explained by that.

If so, then I need (120-100)+(590-571)mm of spacers in the current setup that could be removed (i.e 39mm)...

I don't think so - as above, my gut instinct is that the difference in "stack" IS essentially the difference in headtube meaurements (with 1mm margin of error from somewhere). Realistically, the only thing that can change from one frame to another is the headtube length - I'd be very surprised if there was an EXTRA 20mm difference somewhere.

However, it is possible that the small bike is assembled using a different amount of spacers to the larger bike, so to be sure, and to get a feel of how much you would need to loose in stack height, can you measure the individual stack heights of the existing setup - headset(top and bottom cups), stem and spacers (above and below stem). You don't need to disassemble anything - just hold a tape measure against it and note each item in series. A picture would be helpful, too. We'll then be able to work out where we can "gain" the length needed to accomdate that longer headtube...

larkim

Cheers. Done some measuring, and the tube is definitely 100mm, so that part is easy. I hadn't twigged about the 571mm being that far (doh!) so with a tape measure out I reckon the most likely candidate for that is from the top of the headtube down to the axle height. So the extra 20mm or so is just the head tube. There are about 17mm of spacers in there, and a small space above the steam too, so 20mm looks doable with the stem flush against the top cap of the headset. I'll post some photos later, but thanks for all the help so far!

jimothy78

larkim wrote:

Cheers. Done some measuring, and the tube is definitely 100mm, so that part is easy. I hadn't twigged about the 571mm being that far (doh!) so with a tape measure out I reckon the most likely candidate for that is from the top of the headtube down to the axle height. So the extra 20mm or so is just the head tube. There are about 17mm of spacers in there, and a small space above the steam too, so 20mm looks doable with the stem flush against the top cap of the headset. I'll post some photos later, but thanks for all the help so far!

Check the height of the stem, too (of the part around the steerer tube, obviously) - looks quite tall in the Spesh pic, so potential for losing a good few mm there (and as I said earlier - a new, shorter stem may well be advantageous from a steering point of view, and will make the bike's reach feel more familiar if your boy's going up two sizes at once).

larkim

Thanks again - foolishly I didn't get the tape measure out for that, but as you suggest it is quite a large one.

Ref "stack", I've found various images of stack measurement and it appears that this is the perpendicular height from the centre of the BB / crank to a horizontal line drawn from the top of the headtube. So we can discount that as part of the overall discussion.

Am I right in thinking that the stem would normally be about 3mm taller than the fork tube inside it? I've seen vids of fork replacements where the instruction has been to cut off the tube 3mm lower to allow the star-nut cap to be inserted. There's a spacer at the top of the fork on the hardrock, so I suspect that they cut all forks for this bike to the same tube length, and then differentiate between the different bikes simply by different spacer arrangements.

The Rookie

The steerer tube in the fork should end about 3-5mm below the top of the stack, whether you have the stem on top or a spacer.

You can get lower stack height stems, lower stack height headsets or remove/change spacers to change the total stack height.

Best bet is to measure your current total stack height from on top of the headset top cap to the bottom of the top cap on top of the stack, split that into stem and spacers, give us the numbers and we'll suggest what can be done.

larkim

OK, here are some pics and measurements of the area above the headset.

Whole area (note spacer above the stem too) -

Tape measured -

Spacers - 2 x 7mm? -

Also note that this ebay auction is for a 19inch model, and the spacer arrangements at the top are the same as on the 15.5 model that I have - so my theory about all forks being cut to the same length is nonsense! http://www.ebay.co.uk/itm/SPECIALIZED-HARDROCK-MOUNTAIN-BIKE-19-INCH-FRAME/111464359341?_trksid=p2045573.c100033.m2042&_trkparms=aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20131017132637%26meid%3Dc4a5c9168c7348e5a43ce4cc619353fc%26pid%3D100033%26prg%3D20131017132637%26rk%3D4%26rkt%3D4%26sd%3D221535650011

Cheers!

The Rookie

You have 15mm of spacer below the stem and 5mm above, so that covers the 20mm difference in head tube length, additionally the stem looks to have a stack of about 43mm, down to about 38mm is readily available, so I don't see you having a problem, but at worst case a new stem will fix it.

larkim

Just out of curiosity, I see most fork / stem installation guides require a 3mm gap at the top of the steerer tube where the stem overlaps. Yet, quite clearly as there is a spacer at the top of this stem, that can't be the case on this bike.

What is the logic for the 3mm gap?

Chunkers1980

The spacer on top if to give the gap so that it can be preloaded

jimothy78

larkim wrote:

Just out of curiosity, I see most fork / stem installation guides require a 3mm gap at the top of the steerer tube where the stem overlaps. Yet, quite clearly as there is a spacer at the top of this stem, that can't be the case on this bike.

What is the logic for the 3mm gap?

The gap at the top applies to whatever is at the top of the stack - sometimes this is the stem, sometimes it's a spacer. If the instructions mention the stem, then this is purely because they are assuming the stem is uppermost.

The gap's purpose is to allow you to preload the assembly correctly using the topcap. Tightenign the topcap pulls up on the steerer (via the star-fangled-nut), pulling the fork's crown upwards and into the headset assembly. If there wasn't a gap, the chances are that the topcap would tighten onto the steerer tube itself, rather than the spacers/stem stack. This would fail to push everything together properly, meaning there'd likely be play in the headset, which would affect steering and bearing life.

Sometimes people get the same problem because they tighten the stem's pinch bolts before the topcap - again, this prevent the slack being taken out of the system lower down, because the topcap bolt is only tightening the cap relative to the stem, rather than relative to the crown of the forks.

larkim

Makes perfect sense when explained like that - thanks both!