Ridley cross bike sizing?

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Ridley cross bike sizing?

Postby outontwo » Sun Nov 04, 2012 7:24 pm

Does anyone have experience of choosing the right size Ridley Cyclocross bike? The standover heights look huge and are such that I'd have to go several sizes down from bikes I'm used to and comfortable on to get adequate clearance (55/56 down to 50) and use a bar stem 30mm longer to achieve the same reach. I'm concerned that the set up won't feel right and throw too much weight over the front wheel.

I know that the simple answer would be to sit on some! However, they're not that common in the uk and I'd have to travel some distance to see some which I'd rather avoid and then many shops don't always have every size in stock.

I've put together a simple chart which compares measurements from my 2 most used bikes alongside the Ridley dimensions from their website. I'd be pleased to mail this anyone who has the time & inclination to mull over this and share their thoughts!


cheers and thanks
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Re: Ridley cross bike sizing?

Postby Brucey » Sun Nov 04, 2012 8:23 pm

the standover issue is similar to what happens when you go shopping for an MTB. Similar reasons, too.

A 30mm increase in stem length isn't such a big deal, plus if used as intended, you may find that a slightly shorter reach on a CX bike is a good idea; a smaller frame will give you scope for this.

Re the other issues; you don't say what you are comparing the bike with, exactly. Proper CX bike reach etc is often not a million miles away from a road racing bike with compact frame geometry, and the chainstays are often pretty short, too.

There is generally no comparison with touring bikes, although there are some framesets out there called CX frames which are not really intended for racing, but are more like light tourers, with mudguard eyes etc.

cheers
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Re: Ridley cross bike sizing?

Postby outontwo » Sun Nov 04, 2012 8:58 pm

Thanks Brucey. The other Bikes are a Colnago "Dream B Stay" road bike and a Specialized Tricross single speed. The intended use is coastal tracks and woodland trials but with a 10 mile road trip from home to get there. The Tricross size & set up has been perfect for this but the single speed (or rather the rider) has its limitations on some of the Dorset hills.
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Re: Ridley cross bike sizing?

Postby ian5spot » Sun Nov 04, 2012 9:02 pm

I was asking in my LBS last week about sizing for a Ridley Crossbow and, although I am 6ft 2in and usually ride a 58cm road bike, the guy in the shop suggested I would need a much smaller frame size at about 54cm. I have tried to find something online to confirm this, but had much luck.

I hope this helps.
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Re: Ridley cross bike sizing?

Postby Brucey » Sun Nov 04, 2012 9:05 pm

mad thought; if the Tricross is nearly OK, would it fit the bill with (say) a hub gear instead of the SS setup?

cheers
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Re: Ridley cross bike sizing?

Postby 531colin » Sun Nov 04, 2012 9:24 pm

I just randomly looked at Ridley's site....its the "X-Fire" or something.....

http://www.ridley-bikes.com/gb/en/bikes/4/66/cyclocross/x-fire-1202c#tab-bike-info....click on "geometry"

They measure frame size centre to centre....the normal UK way of measuring is BB centre to the TOP of the seat tube....so a Ridley 54 actually measures 58....is this the cause of the confusion?

Somebody who can actually work a computer could post the picture and table....
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Re: Ridley cross bike sizing?

Postby Brucey » Sun Nov 04, 2012 10:18 pm

Image

picture

Ridley X-Fire Frame Geometry (main dimensions)
Seat Tube c-c (A)/Top Tube (C) /Head Tube (D)/ Seat Angle (E)/ Head Tube Angle (F)/ Standover (J)
48.0 52.5 11.5 74.0 72.0 82.5
50.0 53.0 12.5 74.0 72.0 83.5
52.0 53.5 14.5 73.0 72.0 85.0
54.0 54.5 16.5 73.0 72.0 87.0
56.0 56.0 18.5 73.0 72.0 89.0
58.0 57.5 20.5 73.0 72.0 91.0
60.0 58.5 19.8 73.0 72.0 90.0

Dimension B is 4cm greater than A in every case. More dimensions on Ridley's page as per Colin's link.

cheers
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Re: Ridley cross bike sizing?

Postby 531colin » Sun Nov 04, 2012 11:54 pm

Ridley standover height...
take their 54....which actually measures 58 by the usual UK method.
700c wheel, so the axle is 350mm high BB drop is 61mm, so the BB is (350-61) 289mm high.
BB to top tube centre is 540....BB to top of seat tube is 580....lets guess BB to top of top tube is 555 (assumes top tube is 30mm diameter)
So standover is BB height plus BB to top of top tube 289+555 = 844....its actually less than that, as the seat tube isn't vertical
.....Ridley quote 870 standover
Just as a comparison, Spa's 58 audax has standover of 830.

actually, compare Ridleys 58 and 60 (they are seriously big!) and you will find anomalies....
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Re: Ridley cross bike sizing?

Postby outontwo » Mon Nov 05, 2012 8:25 am

Thank you to everyone for their thoughts & info. I had measured my current bikes using the same datums (c-c) as the Ridley chart so the data is comparable. It remains that in order to get a safe & usable standover height the top tube will significantly shorter than I'm used to which will neccessitate a longer stem. How will this feel and steer?

Ian5spot:- Did you manage to get on a suitable ridley or was it a musing over the catalogue situation with the shop assistant?
Brucey:- I have considered gearing up the tricross but it's great as a ss for keeping the legs in and pretty well zero maintainance!

I've been riding & messing about with bikes since 1988. If I buy the wrong size frame at this stage I'll never forgive myself! Ironically I picked up the Tricross as a 'ridden once' Ebay bargain because the owner had bought the wrong size!


Thanks again for your time & thoughts
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Re: Ridley cross bike sizing?

Postby Brucey » Mon Nov 05, 2012 9:17 am

re the stem length; if I had to draw a comparison I'd say 1" on the stem is similar to a 5mm difference in trail; yes, it is different, you might feel the difference, but you will soon get used to it. It certainly won't instantly turn the steering into a tiller. Those top tubes do seem short, even bearing in mind the intended purpose.

Re the tricross; a Sturmey Archer S2 hub will slot right in and give you two gears instead of one, no cables, mess or fuss. The only fly in this ointment is that this hub is a 'gear up' hub not a 'gear down' hub, (which is most annoying...). It means that you can have a 40-something gear and a sixty-something gear, but the sprocket and chainring need to be set for the forty-something gear. This can be a pain when you convert back to singlespeed operation.

The SRAM A2 is similar gearing wise but an automatic shift instead of a backpedal shift. Even though it is slightly lighter in weight, it has a steel shell, not an alloy one.

The gearing/conversion issue can be addressed by (say) running 36/20 on the hub gear, and 40/16 on the SS. This means that a 110BCD chainset with a choice of two chainrings is required, but (cunningly) the chain can stay the same length for both setups.

cheers
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Re: Ridley cross bike sizing?

Postby outontwo » Mon Nov 05, 2012 9:53 am

Thanks Brucey....are you related to Sheldon Brown by any chance? :wink: You have such a wealth of information. It's going to take me some time to digest it all and make a decision but your input is certainly appreciated.

Cheers
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Re: Ridley cross bike sizing?

Postby mrjemm » Mon Nov 05, 2012 10:28 am

Brucey wrote:mad thought; if the Tricross is nearly OK, would it fit the bill with (say) a hub gear instead of the SS setup?

cheers


Talking from lack of knowledge here, but would cable routing be troublesome on such a project? I guess you'd have to get cable guides brazed/welded on, unless there are bolt on ones available.

And more ignorance to show... Thinking about cross bikes with a high standover. With all the running mounts and dismounting on the go, in slippery conditions, there must be quite strong potential for pain infliction to delicate places.
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Re: Ridley cross bike sizing?

Postby reohn2 » Mon Nov 05, 2012 10:54 am

mrjemm wrote:And more ignorance to show... Thinking about cross bikes with a high standover. With all the running mounts and dismounting on the go, in slippery conditions, there must be quite strong potential for pain infliction to delicate places.


My thoughts too,Cross bikes are made to race,the high s/over is for shouldering the bike to overcome obsticles.
Compact frames have a lot going for them when offroad :)

EDIT:- to omit the words mounting/dismounting Just realised that's silly as high SO doesn't help at all :oops: ,that's why I prefere compact frames.
Last edited by reohn2 on Tue Nov 06, 2012 8:04 am, edited 1 time in total.
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Re: Ridley cross bike sizing?

Postby 531colin » Mon Nov 05, 2012 2:43 pm

I don't think they really can have standovers as high as the website says......unless "standover" in American is "crotch height" in English?
It looks like a horizontal or almost horizontal top tube to me.

I imagine the Ridleys will be sensibly stable....head angle is always 72deg, fork offset is not listed, but my guess would be the standard road bike 45mm. A biggish tyre with a lot of tread will give stable, self-centering steering with 72 deg/45mm....this is what Surly's 700c LHT uses. I don't think 1" on the stem will be a problem.......do you notice the steering feels different on the hoods to on the tops?
I think a short top tube is well down the list of things that change ride character....unless you dont like toe overlap, in which case, check it out.
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Re: Ridley cross bike sizing?

Postby Andyw » Mon Nov 05, 2012 10:16 pm

I know this doesn't answer you question but may help a little.

I ride a Ridley Orion 60cm I've just put together a CX bike with a 60cm Kinesis Evo 3 frame and a stem off and old giant road bike (Not sure how long need to check).

I've given them a quick measure and there doesn't seem much difference. Only a cm or do on the relative top tube (back of saddle to end of stem).
Which is what I'm after as I intend to use it as a winter road bike and for some serious páve in the new year.

I've not ridden the CX bike yet but will keep you informed as to how it feels.
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