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Why such a large stack of spacers on pro's bikes??(13 posts)

Why such a large stack of spacers on pro's bikes??SJT
Jan 30, 2003 7:20 AM
I'm looking at building up my first CX bike and right now I'm trying to get the best sized frame (custom or stock) that will fit my measurements. Am I wrong in assuming that if you have a frame that is fitted well to you, you wouldn't need many spacers to raise your stem height? Maybe one or two? Well I have been looking at some of the pro's bikes on cyclocrossworld.com and it seems almost all of them have quite a large stack of spacers under their stem. Is this common in CX, or are are they just riding frames a size or two too small on purpose? I'm really curious because the whole stack height issue might rule out an otherwise nice frame for me.

If it was necessary to have a high stack height for a particular frame, would it be a better option to get the fork legs built a bit longer to bring the front end higher and then use less spacers? Thanks in advance for your help.
-Steve
re: Why such a large stack of spacers on pro's bikes??1x1 Speed Craig
Jan 30, 2003 8:21 AM
Not sure. Longer fork legs would affect handling, though. They could try a higher-rise stem instead of so many stack spacers, though (i.e. - switch from 0-degree to 10-degree stem).

Craig
My Biking Website
re: Why such a large stack of spacers on pro's bikes??SJT
Jan 30, 2003 8:34 AM
Craig,
I've been wanting to tell you how much I like your website, very well done.

As for the spacer issue, I'm a bit confused as well. If these pros are being sponsored, you would assume they would be given custom-built or perfectly-fitted stock frames for their size. I just don't get why so many of them have so many spacers. I'm sure someone on this board can clear this up.
-Steve
re: Why such a large stack of spacers on pro's bikes??phatlizard
Jan 30, 2003 8:55 AM
The head-tube should be longer - that would be best! If one goes custom that should be easy to do!
I think the CXpros are Roadies at heart and they would hate 10° stems - way too mtb-ish!

Christian
Germany
(I only mention that in case I make too many spelling faults ;) ... )
re: Why such a large stack of spacers on pro's bikes??atpjunkie
Jan 30, 2003 10:59 AM
and note, having that many spacers compromises the functionality of a carbon steer tube.
re: Why such a large stack of spacers on pro's bikes??flyweight
Jan 30, 2003 8:54 AM
The reason is simple. Threadless headsets generally have less stack height than threaded headsets and most framebuilders have not modified their frames to include longer headtubes to compensate for this. This means you need more spacers to compensate. The situation is even worse on frames with internal or integrated headsets. On a cross bike making the headtube taller is often not a good idea because that would raise the top tube which would compromise oh-so-important crotch clearance. You can't simply make the headtube longer and leave the top tube where it is with most lightweight aluminum tubesets.
So how high is too high when it comes to spacers??SJT
Jan 30, 2003 11:10 AM
So how high would you want to go with the spacers? The frame I'm considering has a 1" head tube so take that into consideration. I believe the owner of my LBS said no more than about 25-30mm, more than that is asking for trouble with a 1" steerer tube. Does that sound about right? It seems as though some of the pro's have more than that (tough to judge from the pics), but they might be running 1.125" head tubes which my LBS said he would go as high as 40mm with those.
-Steve
So how high is too high when it comes to spacers??atpjunkie
Jan 30, 2003 1:20 PM
yes, stay low especially with a 1". that area won't handle the torque from the bars. most pro's (exceprt those riding Ridley's) use 1.125 so not as much an issue. I still say lower is better but I'm big. Remember Pro's get theirs free, have a mechanic to check and replace etc... so don't let their 'expendable' set ups guide you.
re: Most Intellegent Explanation I've heardrichpierce
Jan 31, 2003 10:28 AM
That made total sense. I had never thought about the transition from threaded to threadless headsets, the inability to adjust handlebar height by simply raising or lowering the stem in the steerer tube, and its effects on frame design.
re: Why such a large stack of spacers on pro's bikes??DropTheHammer
Jan 31, 2003 12:14 AM
If you look at Euro pro bikes, they usually don't have a big spacer stack. American companies have built their frames taking cues from MTBs, creating more standover height with a longer top tube. The drop created by the lower top tube means a smaller head tube height, which needs more spacers. Look at frame geometries from different companies. You will see a Euro-made 58cm frame with a 57 top tube, and an American 56cm frame with a 57cm top tube. It's basically a bad trend in the industry.
re: Why such a large stack of spacers on pro's bikes??atpjunkie
Jan 31, 2003 10:05 AM
can you further explain this? I have 2 cx bikes 1 Euro and 1 US. Euro is 57 with a 59 TT and the American is 58 with a 59 TT, both would be considered "long". how does a long TT affect Steer Tube height? even with a sloping TT (like an MTB) the TT slopes up to the steer tube joint making very little diff. in steer tube lengths between standard and compact geometry's. The 'drop" as you say is at the seat tube no the head. In road bikes it depends on mfr. and country of origin. Italian Bikes tend to run short in the TT while some Northern (Belgian) bikes run long. Lemonds (made in USA but to Greg's quite Euro Specs) are as well long. confused, please elaborate.
Thx
re: Why such a large stack of spacers on pro's bikes??hummu
Jan 31, 2003 12:35 PM
Perhaps what Drop the Bar is saying is that it seems North American designers of cross bikes tend to design frames with a shorter seat tube in relation to the top tube. The ST is the one to key in on in the response, not the TT. With a shorter ST, regardless of TT length, the head tube will be shorter, unless the TT slopes up from the ST to the HT a la Rivendell.

My guess is that this comes from the MTB background of most North American bike companies. Look at the cross offerings of Kona, IF, the old Bontragers for examples.

When I ordered my Marinoni, I specified the ST to be measured centre to centre (56 cm). Marinoni usually measures centre to top. So my 56/56 c to c frame would be referred to by Marinoni as a 58 with a 56 TT. Now I have a bike that I can just straddle, but the bars are higher than they otherwise could be if I got a stock Marinoni. Oh, and I still have a huge chunk o spacers on that aluminum steerer tube.

As aptjunkie has pointed out, this isn't really a North America v Euro thing as designs change from company to company.
re: Why such a large stack of spacers on pro's bikes??atpjunkie
Jan 31, 2003 2:53 PM
exactly, and why don't they standardize the measurements? some are c-c, some c-t and some (De Rosa's) for example are from the top of the bB Shell to the top. it's silly. let's all get on the same page (mfr's)