Choosing a Frame Type and Size

[MacB]

Hi, as some of you may know I'm awaiting delivery of a wheel built around the SRAM I-motion9 geared hub. My original intent was to put this onto my Giant CRS Alliance. However this will mean messing about with the chainset, possibly an EBB, or a chain tensioner. The idea was always hassle free commuting, I'm nowhere near ready for fixed or SS. But now I'm wondering if I'd be better off with a new frame built around this wheel allowing me another bike. So:-

Type of frame - I'm drawn towards a steel frame, fairly relaxed geometry, horizontal dropouts(which way should they face?), but would appreciate input on type of frame most suited for a hub gear bike. The wheels would be 700 x (up to) 35 and need to accomodate full guards and a rack, v brakes preferred.

Size of frame - my current is a large under Giants compact geometry covering S, M, L & XL, official standover height of 81.5cm, measured my current floor to saddle as 104cm. I've gotten really confused over the variances in frame sizes. I'm 6ft 1, have a floor to crotch measurement, as per sizing sites, of 90cm.

I was thinking of buying second hand but really am confused, will keep looking at sizing info etc. If anyone has any good links, answers, or a bike/frame, they think would fit the bill please let me know....thanks.....Al

 

[hubgearfreak]

Type of frame - I'm drawn towards a steel frame, fairly relaxed geometry, horizontal dropouts(which way should they face?)

but would appreciate input on type of frame most suited for a hub gear bike. The wheels would be 700 x (up to) 35 and need to accomodate full guards and a rack, v brakes preferred.

I'm 6ft 1

I was thinking of buying second hand

OK, that's quite a post you just made. but i think that there's four questions above.

1. either way.
there's picture in the link below. any that aren't vertical like the top two on the right http://www.sheldonbrown.com/gloss_dr-z.html#dropout you will have with your hub (or need to get) the correct anti-rotation washers to match whichever dropout you have

2 an old galaxy or similar touring bike would be ideal - but make sure that you don't get a newish one with horizontal dropouts.. you will probably need to get the rear triangle re-spaced. http://www.sheldonbrown.com/frame-spacing.html
if you want new, there there's these three for starters.
http://cotic.co.uk/product/bikes/roadrat/flat_bar/
http://www.on-one-shop.co.uk/acatalog/Online_Catalogue_Il_Pompino_135_471.html
http://www.bobjacksoncycles.co.uk/product_info.php?cPath=28&products_id=43

3 & 4 if you do find an old steel frame (and there's no reason why you shouldn't) with traditional geometry, such as the bobjackson in the link above, then get a 23.5inch frame.

 

[MacB]

thanks HGF, I've had a good look and the Cotic Roadrat seems to tick all the boxes without breaking the bank. It would appear I'd need the large/long size which would make sense. The options I can see are:-

Buy complete bike for £587.50, swap bars for my butterflies, and replace rear wheel with new one. Fit rack and guards and get chainline right and I'm away. I could either keep the SS rear wheel or sell it to offset the cost.

Buy frame and forks for £255 - this would leave me £332 to spend on, front wheel, guards, chainset, bottom bracket, chain, seatpost, saddle, v brakes with cables and levers, spacers for stem

I already have rack, tyres, tubes, stem, bars and rear wheel with necessary fittings. In either case I can then sell the Giant to fund this.

Would love some feedback on the cotic and the 2 options I'm looking at above, especially around what to buy if going frame and forks only. Don't need superlight/snazzy, but would like to be buying to last. Would consider secondhand from folks on here, not confident enough to buy on e-bay etc.....thanks.....Al

 

[mickle]

Separate the two issues; frame size : frame type.

The only thing you need to establish is reach. Humans are fairly well standardized so a frame with the appropriate reach will, usually, have enough standover clearance. Reach is a combination of stem length and 'top-tube' length so it's the horizontal measurement from the centre of the seat tube/post to the centre of the handlebar. Stems range from 50ishmm to around 140mm, but 90mm to 120mm handle best. If you are happy with the fit of your Giant simply measure the reach, subtract the length of the stem you intend to use and back reference on the individual frame manufacturer's spec sheet to find the 'frame size'.

I'm 6'1'' with an inseam of around 36.5''/930mm.
My bike; ....... tt: 23.5''/595mm. (st: 19.5/495mm). Reach = 705mm
My other bike; tt: 22''/560mm. (st: 23.75''/580mm). Reach = 670mm

Although the bars on the first one are about 20mm higher reach differs by only 35mm, but the difference between the seat tubes is over four inches. As you can see the seat tube dimension is irrelevant.

As for frame type, forward facing 'horizontal' drop-outs are best for hub gears. Aloonyman frames with horiz drops are rare which would limit you to steel. Vertical drop-outs will work perfectly well if you run a Singulator type chain tensioner. If you must have aloonyman this is your option.

Don't bother with track ends, they complicate wheel removal and you'll not find hub washers to suit.

The other thing to be aware of is OLND (over lock nut dimension) or rear drop-out spacing. Most modern geared hubs are 130mm. It's also the road bike standard. A steel 126mm or 135mm OLND frame may be corrected by 'cold setting' (bending). Cold setting aloonyman isn't advised. Also, best to have a good bike shop do this with the right tool as it's not just about bending the stays in or out, the drop-outs must also be kept parallel (unless you want to replace rear axles on a regular basis).

Hope this helps.

 

[hubgearfreak]

i'd generally agree with all that mickle's written, except for two errors

you can get anti-rotation washers for track ends. (page 13) although personally i'd try and avoid them, especially if you want mudguards

it's 135mm O.L.D. (page 18)

http://www.sram.com/_media/techdocs/iMOTION_9_Ins_E_5_06.pdf

 

[mickle]

Fairy nuff

 

[MacB]

Thanks Mickle and HGF, just to clarify a couple of points:-

I know the new hub geared wheel will be 135mm drop out compliant so the Cotic fits but it has rear facing dropouts rather than forward. Why is it that forward facing dropouts are better?

Mickle, good stuff on sizing it now makes more sense especially re reach. My personal stats are almost the same as yours, measuring my current bike shows, top tube 595mm, stem is 130mm adjustable, so that gives me 725mm to flat bar position. With the butterfly bars this means I have a variety of reach from 670mm to 760mm. Top tube on the Cotic(large/long) is 610mm so that would seem to be within tolerances, I could use a shorter stem if need be?

I'm only looking at this because I want to avoid chain tensioners etc so really want to find a frame with the right sort of drop outs. But what are track ends and how do they complicate wheel removal? A main reason I chose the SRAM hub over the Shimano was ease of wheel removal.

Finally, would I be better buying the complete bike and modifying or the frame and building up?

 

[roadiewill]

How do you measure reach? is it tip of saddle to centre of bars?

 

[mickle]

Track ends face backards, 'horizontal' drop-outs face forwards. Imagine removing the rear wheel, with track ends it's necessary to drop the chain off the chainring to create enough slack to allow the wheel out. With standard horizontal drop-outs the wheel moves forwards to remove it. You can remove the wheel without ever having to touch the chain with your fingers. It's just much easier.

 

[mickle]

How do you measure reach? is it tip of saddle to centre of bars?

'Effective' top-tube (centre of seat post to the (top) centre of the head tube) + stem length, measured horizontally = reach.

ie centre of seat post to centre of bars.

Known as 'effective' top-tube because many bikes don't have horizontal top tubes these days. The length of a sloping top-tube means nothing when sizing a bike. You measure it as if it has a horizontal top-tube.

 

[MacB]

thanks Mickle, understood, the track ends don't preclude the use I intend just add a step to wheel removal. This is whittling down things for me, I now understand various sizing and frame types. So I know I want a steel frame bike with horizontal dropouts, 135mm if new, but can use narrower and get cold set wider if secondhand. I have a fair idea of the size of frame needed, and understand how saddle, bar and stem interact to allow fine tuning of fit after this. So:-

Steel frame - though I like the Cotic Roadrat should I look at another frame with front facing drops? If so where are the best places to look and what should I expect to spend?

Frame or complete bike? - with the Cotic I was seriously tempted by complete bike and just swapping rear wheel. This would have left me a spare wheel to re-convert to a single speed if I wanted to play. Once I started adding up the costs of completing the build the extra £332 for the complete Cotic was looking good value. What other complete steel bikes would fit the bill in the up to £600 price range?

 

[hubgearfreak]

should I look at another frame with front facing drops? If so where are the best places to look and what should I expect to spend?

did you read my earlier replies? there's some there

 

[mickle]

thanks Mickle, understood, the track ends don't preclude the use I intend just add a step to wheel removal. This is whittling down things for me, I now understand various sizing and frame types. So I know I want a steel frame bike with horizontal dropouts, 135mm if new, but can use narrower and get cold set wider if secondhand. I have a fair idea of the size of frame needed, and understand how saddle, bar and stem interact to allow fine tuning of fit after this. So:-

Steel frame - though I like the Cotic Roadrat should I look at another frame with front facing drops? If so where are the best places to look and what should I expect to spend?

Frame or complete bike? - with the Cotic I was seriously tempted by complete bike and just swapping rear wheel. This would have left me a spare wheel to re-convert to a single speed if I wanted to play. Once I started adding up the costs of completing the build the extra £332 for the complete Cotic was looking good value. What other complete steel bikes would fit the bill in the up to £600 price range?

Er.. dunno, I'm not familiar with Cotic but buying a complete bike which is closest is to the spec you want and changing a couple of components is usually cheaper than a ground up build IME.

 

[MacB]

did you read my earlier replies? there's some there

yep, am jotting down specs on the Pompino and the Bob Jackson, was wondering if there wer others to look at....cheers....Al

 

[MacB]

Sorry HGF, I've looked at:-

Cotic - £255 frame and forks - ticks all boxes except the rear facing/track end drop outs, option of complete bike at £587.50. This will take tyres up to about 42mm, comes with 25mm tyres.

Bob Jackson £390 frame and forks - the World Tour looks best but is limited to 700x32 tyre as a max with mudguards. The website doesn't give any info on complete bikes or prices.

On-One Pompino £153 frame only - same tyre/guard limitations as the Bob Jackson but also has the rear facing drop outs like the Cotic. I found the On-One website really hard to follow as well. Can't seem to see a complete bike option for the Pompino in the 135mm O.L.D, all seem to be 120mm. A rough calc on their builder gives a complete bike price of approx £650.

I've already spent £367 on the rear wheel with SRAM hub gear and really don't want to spend fortunes having a custom frame built. I'll keep looking but just how hard to change a wheel do rear facing dropouts make it?